Article Per Year (5 Year)
p-Index From 2020 - 2025
6.358
P-Index
This Author published in this journals
All Journal Ilmu Administrasi Publik Jurnal Online Mahasiswa (JOM) Bidang Keguruan dan Ilmu Pendidikan Konversi Jurnal Ilmiah Kebijakan Hukum Analitika : Jurnal Magister Psikologi UMA JPMI (Jurnal Pendidikan Matematika Indonesia) PROSIDING SEMINAR NASIONAL PROGRAM PASCASARJANA M A T H L I N E : Jurnal Matematika dan Pendidikan Matematika Jurnal Optimalisasi Jurnal Mekanova : Mekanikal, Inovasi dan Teknologi Jurnal Ilmiah Kesehatan Jurnal Ilmiah Keperawatan Imelda Proximal: Jurnal Penelitian Matematika dan Pendidikan Matematika AT-TASYRI' Jurnal Ilmiah Prodi Muamalah Community Empowerment JOLLT Journal of Languages and Language Teaching Journal of Educational Administration and Leadership (JEAL) ADMA: Jurnal Pengabdian dan Pemberdayaan Masyarakat Indo-MathEdu Intellectuals Journal Share: Jurnal Ekonomi dan Keuangan Islam COMSERVA: Jurnal Penelitian dan Pengabdian Masyarakat International Journal on Advanced Technology, Engineering, and Information System (IJATEIS) International Journal of Scientific and Professional Jurnal Ilmu Psikologi dan Kesehatan Jurnal Profesi Pendidikan (JPP) Journal of Sustainable Community Service Bagimu Negeri : Jurnal Pengabdian Kepada Masyarakat IIJSE GEMBIRA (Pengabdian Kepada Masyarakat) Jurnal Inovasi Global Jurnal Pengabdian Kompetitif ISTIFHAM TAFASIR Journal of Multidisciplinary Inquiry in Science, Technology and Educational Research Jurnal Signaling Midwifery Journal Journal of Vocational in Aquaculture (JAVA)
Marlinda Marlinda
Universitas Medan Area
Religion Aerospace Engineering Agriculture, Biological Sciences & Forestry Arts Humanities Astronomy Automotive Engineering Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Dentistry Economics, Econometrics & Finance Education Electrical & Electronics Engineering Engineering Environmental Science Health Professions Immunology & microbiology Industrial & Manufacturing Engineering Languange, Linguistic, Communication & Media Law, Crime, Criminology & Criminal Justice Mathematics Mechanical Engineering Medicine & Pharmacology Nursing Public Health Social Sciences Other

Published : 54 Documents Claim Missing Document
Claim Missing Document
Check
Articles

Found 54 Documents
Search

 1   2   3   4   5 
HUBUNGAN TINGKAT PENGETAHUAN IBU TENTANG DEMAM DENGAN MANAGEMEN DEMAM PADA ANAK BATITA DI DESA PADANG RATU Adramisa, Yogi; Marlinda, Marlinda; Tiara, Tiara
Jurnal Ilmiah Kesehatan Vol 13, No 2 (2024): Jurnal Ilmiah Kesehatan
Publisher : Universitas Muhammadiyah Pringsewu

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52657/jik.v13i2.2421

Abstract

Pemahaman mengenai pengelolaan demam pada anak yang baik menjadi sesuatu yang penting untuk dipahami. Pengukuran suhu tubuh dengan menggunakan termometer merupakan cara yang akurat untuk mengetahui ada tidaknya demam. Orang dengan pengetahuan yang baik akan lebih memahami dan bertindak tujuan penelitian ini yaitu untuk menganalisis hubungan tingkat pengetahuan ibu tentang demam dengan managemen demam pada batita di desa padang ratu kecamatan sungkai tengah kabupaten lampung utara. Jenis penelitian ini menggunakan analitik korelasional dengan desain penelitian cross sectional. Populasi pada penelitian ini yaitu seluruh ibu degan batita di desa padang ratu kecamatan kabupaten lampung utara sejumlah 242 orang, dengan jumlah sampel sebesar 70 orang dengan pengambilan sampel menggunakan teknik simple random sampling. Teknik pengumpulan data yang digunakan adalah kuesioner. Pengolahan data menggunakan uji chi square, dengan p value = 0,02 (
PENGUKURAN POSTUR KERJA OPERATOR PENGISIAN TAWAS MENGGUNAKAN METODE OVAKO WORK POSTURE ANALYSIS SYSTEM (OWAS) DI PERUSAHAAN DAERAH AIR MINUM (PDAM) TIRTA MEULABOH Hartati, Rita; Hidjrawan, Yusi; Marlinda, Marlinda; Ali, Sulaiman
Jurnal Mekanova : Mekanikal, Inovasi dan Teknologi Vol 9, No 2 (2023): Oktober
Publisher : universitas teuku umar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35308/jmkn.v9i2.8545

Abstract

AbstrakPDAM Tirta Meulaboh merupakan perusahaan penyuplai air bersih daerah Aceh Barat, yang mana saat ini perusahaan ini adalah salah satunya yang ada di daerah Aceh barat PDAM Tirta Meulaboh terdapat beberapa stasiun kerja yaitu netralisasi dengan pemberian kapur/gamping, aerasi dengan pemompaan udara, koagulasi dengan pengisian tawas, pengendapan, dan penyaringan. Tujuan dari penelitian ini yaitu Mendapatkan hasil dari pengukuran postur kerja dan grand score kategori tingkat resiko Musculoskeletal Disorders (MSDs) operator pengisian tawas menggunakan metode Ovako Work Posture Analysis System (OWAS). Metode yang digunakan pada penelitian ini yaitu metode OWAS untuk mengidentifikasi dan menganalisis sikap kerja para pekerja. Banyaknya keluhan adanya gangguan 2 musculoskeleta. Hasil penelitian menghasilkan pengukuran postur kerja dengan menggunakan metode OWAS mendapatkan nilai untuk elemen I skor 2, elemen II skor 3 dan elemen II skor 2. Grand score tingkat resiko melalui kategori tindakan OWAS penilaian postur kerja untuk elemen I dengan skor 2 adalah diperlukan tindakan beberapa waktu kedepan, elemen II dengan skor 3 adalah diperlukan tindakan dalam waktu dekat, dan elemen III dengan skor 2 adalah tindakan beberapa waktu kedepan. Kata kunci—PDAM, Metode OAS, Postur Kerja  AbstractPDAM Tirta Meulaboh is a company supplying clean water to the West Aceh area, which currently is one of the companies in the West Aceh area. PDAM Tirta Meulaboh has several work stations, namely neutralization by applying lime, aeration by air pumping, coagulation by filling alum, settling, and filtration. The aim of this research is to obtain results from measuring work posture and the grand score for the risk level category of Musculoskeletal Disorders (MSDs) for alum filling operators using the Ovako Work Posture Analysis System (OWAS) method. The method used in this research is the OWAS method to identify and analyze workers' work attitudes. There are many complaints of musculoskeletal disorders. The results of the research resulted in measuring work posture using the OWAS method, getting a score for element I with a score of 2, element II with a score of 3 and element II with a score of 2. The grand score for the level of risk through the OWAS action category for the assessment of work posture for element I with a score of 2 is that action is required over a period of time. In the future, element II with a score of 3 means action is needed in the near future, and element III with a score of 2 means action in the future.Keywords— PDAM, OAS Method, Work Posture
SOSIALISASI SIKAP DAN MOTIVASI KINERJA PADA KARYAWAN CHIP PROFESIONAL KOMPUTER PEKANBARU Nurul, Nurul; Marlinda, Marlinda
Jurnal Pengabdian Kompetitif Vol. 3 No. 1 (2024)
Publisher : Komunitas Manajemen Kompetitif

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35446/pengabdiankompetif.v3i1.1780

Abstract

Karyawan merupakan aset bagi perusahaan, karena keberhasilan perusahaan dapat diraih karena adanya karyawan yang kompeten dalam perusahaan tersebut. Dengan kualitas kinerja yang baik dari karyawan akan memberikan efek yang positif pada karyawan maupun perusahaan itu sendiri. Sosialisasi dalam rangka meningkatkan motivasi kinerja karyawan, menjadi salah satu alat yang efektif untuk meningkatkan kemampuan dan sikap kerja karyawan menjadi lebih baik lagi. Tujuan pengabdian untuk menambah pengetahuan dan pemahaman pentingnya memotivasi kinerja karyawan melalui program pengembangan yang tepat serta memberikan masukan dan menggali potensi diri karyawan untuk lebih siap dalam dunia kerja yang sesungguhnya sehingga diharapkan setelah mengikuti sosialisas dapat lebih meningkatkan kualitasnya dengan lebih baik sehingga menghasilkan Sumber Daya Manusia yang profesional di masa yang akan datang. Metode yang dilakukan adalah presentasi disertai tanya jawab, pendampingan dan pengarahan tentang motivasi dan pengembangan karyawan. Hasil pengabdian menunjukkan pentingnya meningkatkan motivasi dan pengembangan diri dalam bentuk apapun agar menjadi tenaga kerja yang terampil dan profesional di bidangnya.
Analisis Risiko Investasi Saham Sektor Perbankan Syariah Menggunakan Perhitungan Value at Risk (VaR) dengan Model Simulasi Monte Carlo Marlinda, Marlinda
ISTIFHAM Vol 2 No 1 (2024)
Publisher : Seutia Hukamaa Cendekia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.71039/istifham.v2i1.55

Abstract

Risk is a fact that investors must face in stock investment activities. Investors need risk management and estimation to avoid higher risks due to stock price fluctuations that are difficult to predict. Risk management is a system of supervision and protection to minimize acceptable risks. The risk of a stock can be measured using Value at Risk (VaR). VaR is an estimate of the maximum risk obtained by investors under normal market conditions, periods and certain levels of confidence. One of the methods used to determine VaR is Monte Carlo Simulation which includes the generation of random numbers. This method is considered the most powerful in estimating VaR. This study aims to estimate stock risk on single assets and portfolios at BRIS and BTPS for the period January 1, 2021 - December 31, 2023, using VaR calculation with Monte Carlo simulation. The secondary data used in this study is the daily closing stock price data of PT Bank Syariah Indonesia Tbk (BRIS) and PT Bank BTPN Syariah Tbk (BTPS) during the period January 1, 2021-31 December 2023. Based on the results of the test analysis, it shows that on a single asset, PT Bank BTPN Syariah Tbk (BTPS) has a VaR level of IDR 20,014,498 higher than the VaR level of PT Bank Syariah Indonesia Tbk (BRIS) of IDR 19,947,342. In the calculation of the portfolio with the weight of BRIS = 50% and BTPS = 50% shares shows a loss of Rp15,529,484. The VaR value is lower than the VaR value of each asset, it can be concluded that the diversification effect can minimize the risk of stock investment.
Komparasi Return dan Risiko Saham Syariah dan Konvensional Pada JII dan IDX30 Periode 2019-2023 Marlinda, Marlinda; Syahputra, Hendra
AT-TASYRI': JURNAL ILMIAH PRODI MUAMALAH Vol. 16 No. 1 (2024): At-Tasyri': Jurnal Ilmiah Prodi Muamalah
Publisher : Prodi Hukum Ekonomi Syariah STAIN Teungku Dirundeng Meulaboh

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.47498/tasyri.v16i1.3303

Abstract

The purpose of this study is to compare the average return and risk of Islamic stocks and conventional stocks on the JII and IDX30. Data was taken from the IDX website which provides data on companies listed on the JII and IDX for the 2019-2023 period and Yahoo Finance which provides monthly stock closing price data on the JII and IDX during the 2019-2023 period. The sampling technique used purposive sampling method so that 3 sharia stocks and 5 conventional stocks were obtained. Data analysis uses descriptive and inferential statistics using a t-test to draw conclusions. The results of the Independent Sample T Test showed that the return variable obtained a significance value of 0.777>0.05 and the risk variable obtained a significance value of 0.209>0.05. So it is concluded that Islamic stocks and conventional stocks do not show significantly different levels of return and risk.
KOMUNIKASI, INFORMASI, DAN EDUKASI (KIE) MEDIA FLASH CARD EFEKTIF MENINGKATKAN PERSEPSI IMUNISASI HPV Marlinda, Marlinda; Tussellawati, Hani; Madiyanti, Desi Ari
Jurnal Ilmiah Keperawatan IMELDA Vol. 10 No. 2 (2024): Jurnal Ilmiah Keperawatan IMELDA
Publisher : Program Studi S1/DIII-Keperawatan Universitas Imelda Medan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52943/jikeperawatan.v10i2.1726

Abstract

The Human Papilloma Virus (HPV) vaccination is a primary prevention measure against cervical cancer. However, the dissemination of information regarding HPV vaccination has not been optimal, leading to negative perceptions among couples of reproductive age about this vaccination. Therefore, the delivery of information through Communication, Information, and Education (CIE) requires the use of appropriate media. This study aims to determine the effect of CIE using flash card media on perceptions of HPV vaccination implementation in Kresnowidodo Urban Village. The design used is a quasi-experimental with a non-randomized control group pretest-posttest design, involving 15 respondents in the intervention group and 15 respondents in the control group from the Family Welfare Empowerment group in Kresnowidodo Urban Village. The instruments used are flash cards and questionnaires, with data analysis using the Wilcoxon test. The study results show a significant effect of CIE using flash card media on the perception of HPV vaccination implementation, with a p-value of 0.022 (p < 0.05). The small, portable flash cards with pictures help improve the understanding of couples of reproductive age about the importance of HPV vaccination. It is recommended that couples of reproductive age get the HPV vaccination as a preventive measure against cervical cancer.
Kajian Kemampuan Membaca Permulaan Siswa Kelas I SDN 38 Sungai Ambawang Marlinda, Marlinda; Afryaningsih, Yunika; Listiarini, Yuni
Indo-MathEdu Intellectuals Journal Vol. 5 No. 5 (2024): Indo-MathEdu Intellectuals Journal
Publisher : Lembaga Intelektual Muda (LIM) Maluku

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.54373/imeij.v5i5.1836

Abstract

This study aims to determine the initial reading ability of grade 1 students of SDN 38 Sungai Ambawang. This type of research uses a qualitative approach. The data collection technique in this study uses the EGRA test. The researcher used the EGRA test in assessing the initial reading ability of grade 1 students of SDN 38 Sungai Ambawang. The EGRA test consists of five aspects, namely knowing letters, reading words, reading words that have no meaning, fluency in reading aloud and comprehension of reading and listening (listening comprehension). The results of the study showed that the ability of grade 1 students of SDN 38 Sungai Ambawang in the aspect of recognizing letters was 77%, of which 5 out of 15 students were still unable to recognize letters. The aspect of word reading resulted from the average ability of students was 69%, of which 6 out of 15 students were found to be in the good to very good category in word reading. The aspect of reading words has no meaning found that 7 out of 15 students are still not good at reading words that do not mean the average score of the whole student, which is 60%. The aspects of fluency in reading aloud and comprehension were found as many as 7 out of 15 students were less able in reading aloud and reading comprehension, their average score was 60%. The aspect of listening (listening comprehension) was found as many as 7 out of 15 students who were not completely good at answering questions given by the researcher about the reading, read with an average score of 63% of their ability
Kemampuan Penyelesaian Masalah Matematis Siswa melalui Soal Cerita Deret Aritmatika dengan Tahapan Ideal: STUDENTS MATHEMATICAL PROBLEM SOLVING SKILLS THROUGH ARITHMETIC SEQUENCE WORD PROBLEMS WITH IDEAL STEPS Marlinda, Marlinda; T, Ahmad Yani; Siregar, Nurfadilah; Meldi, Nadya Febriani
Proximal: Jurnal Penelitian Matematika dan Pendidikan Matematika Vol. 8 No. 1 (2025): Sains Matematika dan Pendidikan Matematika
Publisher : Universitas Cokroaminoto Palopo

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.30605/proximal.v8i1.4627

Abstract

This research aims to describe the mathematical problem-solving abilities of students at SMAN 7 Pontianak regarding story problems in arithmetic sequences, based on the IDEAL stages. The subjects of this study were selected based on their categorization into high, medium, and low ability students. This research employed a descriptive approach with qualitative methods. The instruments used for data collection included problem-solving ability test results and interview sheets.The findings of the study indicate that: (a) subjects with high problem-solving abilities successfully completed all five stages of the IDEAL problem-solving process. (b) subjects with medium problem-solving abilities were able to perform the IDEAL stages, but their results still contained errors. (c) subjects with low problem-solving abilities struggled to complete all five IDEAL stages when solving story problems in arithmetic sequences. Students with lower academic performance were only able to identify problems. They faced difficulties in defining goals and exploring possible strategies, which led to mistakes in the subsequent stages.
Application of Exponential Smoothing Method on Forecasting The Results of Bandeng Pounds in Cot Muda Itam Village-Peureulak District-Aceh Timur: Penerapan Metode Exponential Smoothing pada Peramalan Hasil Tambak Ikan Bandeng di Desa Cot Muda Itam-Kecamatan Peureulak-Aceh Timur Olivia, Mirda; Erviana, Jumarnis May; Saumi , Fazrina; Elviana, Elviana; Marlinda, Marlinda
Mathline : Jurnal Matematika dan Pendidikan Matematika Vol. 7 No. 2 (2022): Mathline: Jurnal Matematika dan Pendidikan Matematika
Publisher : Universitas Wiralodra

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31943/mathline.v7i2.281

Abstract

Pould cultivation until now is counted as a bussines that can provide extraordinary income. Cot Muda Itam Village is one of the villages in East Aceh Regency that cultivates ponds by producing milkfish. Milkfish yields also vary, sometimes increasing and not infrequently experience a dcrease in yields.. Therefore, it is necessary to have a study that can predict the production of milkfish un the next harvest. Forecasting is a process of predicting the values of variables based on known values of previously related variables. Based on the results of data processing and data analysis using the linear exponential smoothing method of one brown parameter with  and MSE value of 16407,241875 it is obtained that the forecast results in the 11th and 12th months of the harvest decrease, namely 587 kg and 580 kg.  
RANCANGAN FASILITAS KERJA OPERATOR PENGOLAHAN ROTI DENGAN PENDEKATAN ERGONOMI MENGGUNAKAN METODE RAPIT ENTIRE BODY ASSESMENT (REBA) DI UD. DONAT ASRI Hartati, Rita; Hadi, Khairul; Hidjrawan, Yusi; Marlinda, Marlinda
Jurnal Mekanova : Mekanikal, Inovasi dan Teknologi Vol 10, No 2 (2024): Oktober
Publisher : universitas teuku umar

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.35308/jmkn.v10i2.10612

Abstract

 UD Donat Asri merupakan salah satu tempat usaha di bidang pembuatan roti, pada pengolahan roti masih adanya keluhan muskuloskeletal  disorders  yang  dialami oleh operator sehingga masih  ada  postur  kerja  operator  yang  kurang ergonomi serta kurangnya  fasilitas  kerja  yang  mendukung  operator  untuk  melakukan aktivitas kerja. Tujuan dari penelitian ini yaitu mengidentifikasi keluhan muskuloskeletal disorders yang dialami pekerja pengolahan roti dengan menggunakan Nordic Body Map, dan merancang fasilitas kerja yang ergonomis. metode yang digunakan pada penelitian ini yaitu metode REBA untuk menentukan  nilai  postur  kerja  operator dengan bantuan Software Ergofellow. Hasil penelitian menghasilkan data tingkat keluhan yang dialami oleh pekerja saat melakukan proses pengolahan roti berdasarkan NBM, keluhan terbesar pada bagian tubuh yaitu sebesar 79,17%, dan keluhan terkecil pada bagian tubuh dengan persentase 33,33%, sedangkan persentase keluhan yang dialami oleh pekerja pengolahan roti berdasarkan NBM menunjukan bahwa  keluhan yang paling  tinggi  yaitu  pada  stasiun  penggorengan persentase  72,30%,  persentase   terendah   yaitu   pada   stasiun   pengemasan  sebesar 48,21%. Penilaian postur kerja dengan software Ergofellow memperoleh skor REBA tertinggi adalah pada posisi kerja 5 yaitu pada aktivitas penggorengan roti dengan  nilai  skor  sebesar  11  dan  dikategorikan  kedalam  action  level sedangkan skor REBA terendah yaitu pada posisi kerja 4 pada aktivitas pembulatan adonan dengan skor REBA sebesar 4 dan dikategorikan ke dalam action level berdasarkan  perhitungan  antropometri  dengan persentil 50 rata-rata yang mana panjang meja yaitu 160 cm, lebar meja kerja persentil 50 rata-rata yang mana lebar meja yaitu 79 cm, tinggi meja kerja persentil 50 rata-rata sehingga didapat urutan tinggi meja yaitu 103 cm sedangkan tinggi  fasilitas kerja  dengan persentil 50 rata-rata sehingga tinggi fasilitas kerja yaitu  150 cm.  Berdasarkan ukuran tersebut  fasilitas  yang  dirancang  sudah ergonomi   karena   menggunakan   penerapan   antropometri   tubuh  pekerja sehingga dapat bekerja dengan nyaman.
Co-Authors AA Sudharmawan, AA Abdallah Al-Shreifeen, Iyad Abdiel Khaleil Akmal Abdul Rahman Adramisa, Yogi Afryaningsih, Yunika Ahmad Yani T Aini, Siti Dhea Nur Alam, Ahmad Noor Ali, Sulaiman Alwathan Alwathan Amanda, Dea Prisca ANDRI KURNIAWAN Aprilia, Nursyam Ardansyah, Ardansyah Ariansyah, Wanda Basuki , Bistari Daud, Daman huri Dewi, Cut Dara Elviana Elviana, Elviana Erlina Erlina Erviana, Jumarnis May Evayanti, Yulistiana Fajar, Ulul Al Gusmawati Gusmawati, Gusmawati Hadi, Rizal Hadiyanto Hadiyanto Hafni Zahara Halim, Abd Harapan, Edi Hartati, Rita Hasan, Hasmulyadi Helmi Hasan Hendra Syahputra Hidayat, Finda Hidjrawan, Yusi Hikmah, Muziatun Indra Jaya Irmayani Irmayani Jamil, Jannatul Juliana, Imroatul Juswandi Juswandi K.M. Aminuddin Kadri, Hanif Al Kaiman Turnip, Kaiman Kartika, Dinda Kasmawati Kasmawati Khairul Hadi Kurniasari, Devi Kusuma, Imam Fatwa Listiarini, Yuni M. Irwan M. Irwan, M. Irwan Madiyanti, Desi Ari Mahmud Alpusari Mahmud Basuki Mardhiyah Nadir, Mardhiyah Masri, Arfi Mauliana Mauliana, Mauliana Mei, Eka Meldi, Nadya Febriani Muh Irwan, Muh Muhammad Faisal Muliadi Nasrah, Rasidah Nellitawati Nellitawati Nissa Prasanti Nurdin, Ambia Nurfadilah Siregar Nurhadia, Nurhadia Nurul Nurul Oktavianti Oktavianti Oktavioni, Dea Olivia, Mirda Pupung Purnamasari Puspasari, Febriyati Putra, Dedi Fazriansyah Rahmadani, Aulia Rahmawati, Talisa Ramadhani, Eliza Ramli Ramli Ramli Thahir Rifma Rifma Rita Hartati Rustam Rustam Sadida, Wahyuni Safitriyawi, Roja Saumi , Fazrina Septiasari, Yeti Sofiyanurriyanti Sufyarma Marsidin Sukma Nur Ardini Sulastri Sulastri Suparno Suparno Syafri Hariansah Syam, Muhammad Taufik Tiara, Tiara Tomo, Tomo Tussellawati, Hani Utami, Vida Wira Veithzal Rivai Zainal Wahyu Widayati, Wahyu Wahyudi Wahyudi Wahyuni, Srie Yandi, M. K. Yoserizal Yoserizal Yusi Hidjrawan Zahirah, Putri Zainuddin, Zainuddin Zulkifli Zulkifli