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Analisis Daerah Potensi Longsor Menggunakan Metode Geolistrik Resistivitas di Danau Kastoba Pulau Bawean Indonesia Karimah Karimah; Adi Susilo; Eko Andi Suryo; Aunur Rofiq; Muhammad F.R. Hasan
Jurnal Penelitian Pendidikan IPA Vol. 8 No. 2 (2022): April
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v8i2.1414

Abstract

Kastoba Lake in Bawean Island Indonesia is a tourist attraction that has a level of vulnerability in landslide disasters. The landslides has been happen. From the large and small scale in the Kastoba Lake. Base on the problem, the landslides occured due to the field of derailment. According to the above statement, it was necessary to know the subsurface structure and the field of avalanche derailment in the kastoba lake area. This data was allowed by geophysical resistivity method which a dipole-dipole configuration with 4 measurement points. The acquisition of data was based on preliminary studies from the analysis of landslide vulnerability level maps (DEM Alos data processing) that have been done first. The results of lithological analysis with geoelectric resistivity methods in this research obtained three layers of subsurface structure, namely top soil (top layer) with a resistivity value of 7-110 Ωm, clay (middle layer) which was a resistivity value of 110-210 Ωm and lava (bottommost layer) which was a resistivity value of 210-357 Ωm. The field of gelincir in the research area was on the top layer of soil composed of weathering of rocks mixed with organic material or leaf/tree decay with an average depth of 7.25 meters. Thus, this research can be one of the parameters of landslide disaster mitigation in the development of geotourism in Kastoba Lake
3D Modelling of Geoelectrical Resistivity Data to Determine the Direction of Landslides in Kastoba Lake, Bawean Island, Indonesia Karimah Karimah; Adi Susilo; Eko Andi Suryo; Aunur Rofiq; Muhammad F.R. Hasan
Jurnal Penelitian Pendidikan IPA Vol. 8 No. 3 (2022): July
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v8i3.1714

Abstract

Landslides are one of the factors caused by subsurface structures that are not compact, and have low density or resistivity values due to changes in groundwater. Rainwater that infiltrates into the ground will reach to an impermeable layer which is identified as a slip plane. This research was conducted in the Kastoba Lake area, Bawean Island, Indonesia. The purpose of this study is to determine the slip plane and the direction of the landslide in the studied area. Data acquisition was carried out based on a preliminary study of residual anomaly contour analysis from gravity data, then geoelectric data acquisition was carried out in the studied area. The results of lithological analysis on 3D geoelectric resistivity modeling in this study obtained three layers of subsurface structures, namely topsoil, clay, and lavas. The slip plane of the study area is above the clay layer (7.25 meters depth). The results of the 3D interpretation indicated that the direction of the landslide was towards the north, as evidenced by the existence of public information that the area studied had landslides with the avalanche direction towards the north.  For further analysis, a factor of safety analysis is needed based on the analysis of the bore hole drilling method in the studied area
Impact of In-House Bolus Thickness on The Percentage of Surface Dose for 10 and 12 MeV Electron Beams Sigma Nur Rismawati; Johan Andoyo Effendi Noor; Yuyun Yueniwati; Fatimah Kunti Hentihu; Margaretha Berek; Ayu Hardianti Pratiwi; Karimah Karimah
Jurnal Penelitian Pendidikan IPA Vol. 8 No. 6 (2022): December
Publisher : Postgraduate, University of Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29303/jppipa.v8i6.2344

Abstract

The surface dose on electron irradiation which is received by the skin does not reach 100%, so a bolus is needed as a compensator material in order to reach or approach 100%. This study aims to create, test, and describe the effect of different thicknesses of boluses that are made of 3D printed TPU, silicone sealant and resin on equivalence with tissue and the percentage of surface dose produced. A bolus with a size of 15x15 cm2 and with variations in thickness of 0.3 cm, 0.5 cm, and 1 cm was imaged by a CT-Scan to analyze the CT-Number value and relative electron density using imageJ software. After that, the bolus was irradiated by a Linac with an energy of 10 MeV and 12 MeV to measure the surface dose using an advances marcus detector. The result of this study showed that 3D printed TPU, silicone sealant and resin are similar to some soft tissues. Silicone sealant has the highest flexibility of the two boluses. In addition, silicone sealant also produces the highest increase in the percentage of surface dose in phantom.