Judul: Analisis Kebutuhan Jumlah Alat Sarad Excavator berdasarkan Produksi Kayu dan Produktivitas Alat pada Hutan Tanaman Industri di Sumatera
Abstrak: Excavator adalah salah satu alat yang digunakan untuk memindahkan kayu dari tunggak ke tempat pengumpulan kayu di lokasi pemanenan kayu pada Hutan Tanaman Industri di Sumatera. Penelitian ini dilakukan dalam rangka menganalisis perhitungan jumlah alat sarad berdasarkan realisasi produksi kayu untuk kegiatan pemanenan kayu. Tujuan penelitian untuk menganalisis jumlah excavator yang dibutuhkan perusahaan berdasarkan data realisasi produksi kayu dan menganalisis pengaruh luas areal HTI terhadap jumlah alat dan realisasi produksi kayu. Metode penelitian menggunakan rumus kebutuhan jumlah alat dan analisis regresi sederhana. Hasil penelitian menunjukkan jumlah alat berdasarkan realisasi produksi kayu didapat PT Sumatera Riang Lestari membutuhkan 56 unit, PT Wira Karya Sakti 201 unit, PT Toba Pulp Lestari 17 Unit, PT Mitra Kembang Selaras 9 unit, PT Arara Abadi 148 unit, dan PT Perawang Sukses Perkasa Industri 12 unit. Luas areal HTI berpengaruh terhadap jumlah alat. Jumlah alat berpengaruh terhadap realisasi produksi.
Keyword: excavator, Industrial Plantation Forest, timber product realization, Sumatra

Judul: Analisis Produktivitas Penyaradan Kayu Menggunakan Bulldozer Pada Perusahaan Pemanenan Hutan Alam di Sumatera Utara
Abstrak: Bulldozer adalah traktor beroda rantai dan memiliki kemampuan traksi yang besar. Bulldozer efisien digunakan di medan kerja yang berat sekalipun, seperti penyaradan kayu di perusahaan pemanenan hutan alam di Sumatera Utara. Tujuan penelitian ini adalah menganalisis antara jumlah kebutuhan bulldozer diperusahaan tersebut dengan jumlah aktual, dan menganalisis hubungan antara jumlah bulldozer dan realisasi produksi kayu. Pada penelitian ini digunakan rumus kebutuhan jumlah alat serta analisis regresi sederhana. Hasil dari penelitian ini perusahaan menyediakan bulldozer sesuai dengan kebutuhan perusahaan tersebut. Pada PT Teluk Nauli mengalami kelebihan bulldozer sebanyak 1 unit. PT Gunung Raya Timber Industries mengalami kelebihan alat sebanyak 1 unit begitu juga dengan PT Panei Lika mengalami kelebihan alat sebanyak 1 unit. Kelebihan jumlah bulldozer sebanyak 1 unit diperkirakan karena bulldozer tersebut digunakan untuk pembuatan jalan sarad sebelum kegiatan pemanenan kayu dilaksanakan. Kelebihan jumlah bulldozer disebabkan oleh kesalahan dalam perhitungan waktu lembur dan waktu kerja sehingga perusahaan menyediakan bulldozer tidak sesuai dengan kebutuhan. Analisis regresi menunjukkan bahwa jumlah bulldozer memiliki hubungan yang signifikan terhadap realisasi produksi kayu. Kata kunci: analisis regresi, bulldozer, penyaradan, produktivitas, The bulldozer is a tractor on a chain wheel and has great traction capability. Bulldozers remain efficient even in tough work areas, such as skidding timber at a natural forest harvesting company in North Sumatra. The purpose of this study was to analyze the actual number of bulldozers needed by the company, and to analyze the relationship between the number of bulldozers and the realization of wood production. In this study, the formula for the need for the number of tools and simple regression analysis was used. The results of this study the company provides bulldozers according to company needs. PT Teluk Nauli experienced an excess of 1 bulldozer unit. PT Gunung Raya Timber Industries experienced an excess of 1 unit and PT Panei Lika experienced an excess of 1 unit. The excess number of bulldozers by 1 unit is estimated because the bulldozers were used for skid trail construction before the timber harvesting activity was carried out. The excess number of bulldozers was caused by an error in calculating overtime and working hours so that the company provided bulldozers that were not in accordance with the needs. Regression analysis shows that the number of bulldozers has a significant relationship with the realization of wood production. Keywords: bulldozer, productivity, regression analysis, skidding
Keyword: analisis regresi, bulldozer, penyaradan, produktivitas

Judul: Hybrid solar cells of ZnO nanoparticles/chlorophyll was modified metal ions (Zn2+ and Cu2+ )
Abstrak: Zinc Oxide (ZnO) is a n-type semiconductor with a wide the energy band (Band Gap) is 3.37 eV at room temperature and 3.34 eV at low temperature with a large exiton binding energy is 60 meV. ZnO has been synthesized by hydrothermal method, resulting in a decrease in particle size over the duration of the hydrothermal changes. Crystallographic structure of ZnO were characterized using XRD, has shown the characteristic pattern of a hexagonal wurtzite structure, the crystallite size increases to changes in particle size. Changes in particle size has also led to a change in the absorption peak of ZnO as has been demonstrated posted under test using the optical properties of UV-Vis spectrophotometer. Changes of this uptake has also led to changes in the energy band gap, which increases its band gap energy of the particle size. In electronic applications, especially in solar cells. Chlorophyll is considered less effective, because of their very nature are easily degraded as a result of several reactions which are acid, lighting and temperature. The results of the stability test using a halogen lamp 34 W/m2 for 5 hours, that the substitution of chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form more stable than natural chlorophyll. The characterization of the optical properties, the combination of ZnO / chlorophyll in the form of hybrid films has led to a shift in the absorption region of ZnO becomes more widely from the UV to Visible. ZnO/chlorophyll has absorption range of 350-515 nm, ZnO / Zn-feofitin 332-401 nm and 332-632 nm for Cu-feofitin. The combination of ZnO/chlorophyll and CuSCN as a solid electrolite in hybrid solar cell, a modified chlorophyll with metal ions Zn2+ and Cu2+ has been shown to form a more stable I-V curve. It is characterized by its fill factor value greater than natural chlorophyll. Nevertheless, solar cells with natural chlorophyll has been able to produce higher efficiency values of chlorophyll were substituted.
Keyword: Hydrothermal, ZnO/Chlorophyll modified, Hybrid Solar Cell