This paper presents the details of design and implementation of DC-DC Buck converter as solar charger. This converter is designed for charging a battery with a capacity of 100 Ah (Ampere Hours) which has a charging voltage of 27.4 volts. The constant voltage method is selected on battery charging with the specified set point. To ensure the charging voltage is always on the set point, the duty cycle control of buck converter is set using Fuzzy Logic Control (FLC). The design implementation has been tested on PV (photovoltaic) with 540WP capacity. Based on the test results, this method is quite well implemented on the problem charger

ABSTRAK Rubble Road merupakan pilihan membuat jalan di floor batubara dengan metode blasting. Project ini dilakukan di floor BN, Pit Bendili Prima pada July 2019 lalu dan bertujuan membentuk jalan pengganti dari pit ke dump point. Rubble  road di lakukan pada floor batubara bukan basal dengan interburden yang cukup lebar terhadap basal seamnya. Sehingga dapat dibentuk badan jalan dan terproyeksikan dinding yang lebih tegak terhadap seam floor terganggu. Berbeda dengan metode konvensional dan praktis yang kerap dilakukan, untuk mendapatkan bentuk jalan di area floor dilakukan dumping material. Tentunya ini akan berdampak pada cost tambahan ditahun mendatang. Karena overburden (ob)  kbcm yang dipakai untuk construct jalan, harus digali kembali untuk mendalamkan Pit. Eksekusi rubble road ini juga melibatkan team geotek untuk assesmentnya agar stabilisasi jalan tidak menjadi kendala dimasa mendatang. Kata kunci : rubble road, jalan pengganti, meniadakan rehandle.   ABSTRACT Rubble Road is an option to create a road  on the coal floor by blasting method. The project was carried out on the BN floor, pit Bendili Prima in July 2019 and is intended to provide a replacement road from pit to dump point.Rubble road is carried out on a non basalt coal floor with afairly wide interburden on the basal seam.So that the road can be formed and projected a wall that is more upright against the disturbed seam floor.Unlike the conventional and practical methods that are often done, to get the shape of the road in the floor area is carried out dumping material.Surely this will have an impact on additional costs in the coming year.Due to the over burden (ob) used for road construction, it has to be dug back to deepen the pit.The execution of this road also involves the geotech team for its assessment, so that road stabilization is not an obstacle in the future.

An analysis of stability needs to predict stress-strain values of soil, rock, and/or intermediate material (soil-rock) layers around the gate shaft during excavation works. Selection of stress-strain of intermediate material foccused on this paper will affect to the analysis result. This analysis concerned on some consideration to the selection the stress-strain parameters in determination of c’ and f’ parameters. In excavation works,the parameters were applied to the stability analysis of gate shaft construction of dam construction. The stability analysis used a 2 D software of PLAXIS. Each condition of gate shaft was reinforcement and un-reinforcement wall types. From several analyses, the parameters of c’ and f’ from stress-strain of soil was smaller than intermediate material.Keywords: Cohesion; angle of internal friction, stress, strain, gate shaft.Abstrak Suatu analisis stabilitas perlu untuk memperkirakan besarnya tegangan-regangan tanah, batuan, dan atau lapisan material peralihan tanah-batuan (intermediate material) di sekitar lubang galian vertikal. Pemilihan tegangan-regangan dari material peralihan tanah-batuan yang difokuskan pada paper ini akan berpengaruh terhadap hasil analisis. Analisis ini memusatkan perhatian pada beberapa pertimbangan pemilihan parameter tegangan-regangan dalam analisis stabilitas saluran pengalihn vertikal pada konstruksi dam. Analisis stabilitas ini menggunakan software Plaxis 2 D (dimensi). Masing-masing tipe dinding saluran vertikal ini adalah dengan dan tanpa perkuatan tulangan. Dari beberapa analisis, parameter c’ dan f’ dari tanah adalah lebih kecil dari material peralihan.  Katakunci: Kohesi, sudut geser dalam, tegangan, regangan, saluran pengalihan vertikal.