Judul: Penjadwalan Kegiatan Mengajar Bimbingan Belajar Menggunakan Integer Linear Programming: Studi Kasus Bintang Pelajar Cikarang
Abstrak: Penjadwalan menjadi salah satu permasalahan yang sering dihadapi dalam penugasan suatu organisasi termasuk lembaga pendidikan, salah satunya yaitu bimbingan belajar. Penjadwalan ini melibatkan kombinasi antara banyaknya tenaga pengajar, mata pelajaran, kelompok belajar, sesi belajar, dan ketersediaan ruangan. Tujuan dari penelitian ini adalah memodelkan masalah penjadwalan dengan meminimumkan bobot sesi belajar setiap kelompok lalu mengimplementasikan model tersebut pada masalah penjadwalan kegiatan mengajar di Lembaga Bimbingan Belajar Bintang Pelajar Cikarang. Masalah tersebut diselesaikan menggunakan integer linear programming. Dengan bantuan software Lingo 19.0 diperoleh solusi optimal berupa jadwal kegiatan mengajar untuk periode waktu satu bulan yang memenuhi seluruh kendala., Scheduling is one of the problems faced in the assignment of an organization including educational institutions, one of which is tutoring. This scheduling involves the number of teaching staff, subjects, study groups, study sessions, and room availability. The purpose of this study is to model the scheduling problem by minimizing the weight of each group's study sessions and then implement the model on the scheduling teaching activities at Tutoring Institutions Bintang Pelajar Cikarang. That problem was solved using the integer linear programming method. With the help of Lingo 19.0 software, an optimal solution is obtained in the form of a teaching activity schedule for one month that satisfies all constraints.
Keyword: Bintang Pelajar Cikarang, integer linear programming, learning session weight, scheduling, tutoring institutioins

Judul: Penjadwalan Kegiatan Belajar Mengajar di Lembaga Bimbingan Belajar dengan Menggunakan Integer Linear Programming dan Weighted Sum Method
Abstrak: This manuscript provides integer linear programming model to schedule teachers in a tutoring agency. The objective function of this model is to maximize students achievement with regard to teacher performance and to minimize the total cost for teachers which includes daily wage costs and transportation costs. These two objective functions are combined into one objective function using a weighted sum method. The model assuming that: (1) the study group has been formed and each group had time and place of teaching and learning activities, (2) it considers time availability of the teachers, (3) a teacher can teach at different locations within a day, (4) there is no time lag between the two time periods of teaching in a day, except the pause for switching locations.
Keyword: weighted sum method., scheduling, integer linear programming, tutoring agency,

Judul: Hydroxyapatite-Chitosan Composite Coating on Stainless Steel 316 to Improve Corrosion Resistance
Abstrak: Metals that were used in bone implantation should have good corrosion resistance that were not easily corroded when implanted into the body. Metal corrosion resistance of stainless steel 316 can be enhanced through the metal coating by hydroxyapatite-chitosan composite with composition ratio of hydroxyapatite (gram) and chitosan 3% (mL) 0.2:0, 0.2:0.1, 0.2:0.5, 0.2:1.0, and 0.2:1.5. Besides improving the corrosion resistance of metal, the presence of chitosan also maintain the position of hydroxyapatite on metal surfaces. Corrosion resistance increases with increasing amount of chitosan added and the best composition of hydroxyapatite-chitosan composite was 0.2:1.0.
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