PENERAPAN MEDIA PEMBELAJARAN CAI (COMPUTER ASSISTED INSTRUCTION) MODEL TUTORIAL UNTUK MENINGKATKAN PRESTASI BELAJAR SISWA

Penelitian ini dilatarbelakangi oleh adanya permasalahan pada proses pembelajaran merakit personal komputer di sekolah menengah kejuruan (SMK) Ika Kartika Tanggulun Kadungora, berdasarkan hasil wawancara, dimana siswa merasa terganggu dengan suasana pembelajaran yang tidak kondusif, komunikasi antara guru dan siswa tidak berjalan dengan baik. Sehingga siswa mengalami kesulitan dalam memahami materi yang disampaikan oleh guru. Penelitian ini bertujuan untuk mengetahui peningkatan prestasi belajar siswa setelah diterapkannya media pembelajaran (CAI) model tutorial. Metode penelitian yang dilakukan adalah Quasi Eksperiment Pretest-Postest Group Design, Pada penelitian ini data pokok yang diperoleh adalah prestasi belajar siswa pada domain kognitif dalam pembelajaran Merakit Personal Komputer. Penelitian dilakukan terhadap satu kelompok eksperimen yang kemudian dipisahkan berdasarkan data dari hasil belajar antara kelompok siswa dengan prestasi tinggi, sedang dan rendah. Setelah nilai rata-rata postes dikurangi nilai rata-rata pretes maka diperoleh selisih nilai rata rata n-gain untuk melihat peningkatan prestasi belajar siswa. Setelah selesai dilakukan perhitungan analisis data penelitian, terdapat perubahan prestasi belajar siswa yang signifikan pada domain kognitif dalam pembelajaran Merakit Personal Komputer dengan menerapkan media pembelajaran CAI model tutorial. The research is conducted based on the problem in the learning process of personal computer asembling in vocational school (SMK) IKA KARTIKA Tanggulun Kadungora. Based on the interview, the students shows the inconvenience towards many reasons: the uncomfortable learning atmosphere and the communication barriers between the teacher and the students. It causes difficulties for the students to receive the learning material given. The research is purposed to find out the learning achievement of the students by implementing the Computer Assisted Instruction tutorial mode as the learning media. The methodology of the research is Petest-postest Quasi-Experimental group design. The main data acquired of the research is the learning achievement of the students in the personal computer asembling. The research is conducted to an experimental group which is then divided based on the data acquired from the learning achievement of the students that varies in several results: high, medium, and low score. In order to know the improvement of the learning achievement of the students, the n-gain (g) is acquired by substracting the average score of postet with the average score of the pretest. After conducting the analysis of the data of the research, it is found that there is a significant difference in the learning achievement of the students in terms of the cognitif domain in applying the computer assisted instruction tutorial mode as learning media in personal computer asembling during the learning activity

PREDIKSI DISTRIBUSI KONSENTRASI REFRIGERANT FLAMMABLE (R-290 DAN R-32) DALAM RUANGAN YANG DIKONDISIKAN AKIBAT ADANYA KEBOCORAN PADA UNIT PENGONDISIAN UDARA (AC)

Penelitian ini membahas tentang kebocoran refrigeran flammable (R-290 dan R-32) pada ruangan, beberapa parameter telah dikaji untuk dilihat pengaruhnya terhadap distribusi pada ruangan; diantaranya leakage rate (laju aliran massa kebocoran), air flow rate atau ventilation rate sebagai kecepatan udara dingin pada satu titik pemasangan (Node) AC pada ruangan. Dengan perbedaan kondisi batas, kebocoran pada ruangan akan ditunjukan dan di analisis. Penelitian ini dilakukan dengan menggunakan kaji numerik menggunakan software CFD ANSYS FLUENT v.13 dengan mengembangkan menggunakan model Species Transport model ini sesuai untuk kedua jenis aliran kompresibel dan inkompresibel, khusus untuk campuran gas antara refrigeran dan udara, algorithma SIMPLE dengan solver Pressure based pada kondisi sistem Transient first order implicit diskritisasi. Jenis Mesh atau grid adalah mesh dengan dominan quadrilateral, pemodelan turbulensi menggunakan Standar K-epsilon di mana model ini cukup untuk memperlihatkan aliran turbulent difusi gas campuran (mixture) antara refrigeran dan udara pada ruangan beserta separasi antara keduanya. Tujuan penelitian ini adalah untuk memprediksi kadar distribusi kebocoran refrigeran flammable (R-290 dan R-32) pada ruangan akibat adanya kebocoran pada unit pengondisian udara (AC). Dari hasil penelitian menunjukan bahwa parameter-parameter leakage rate (laju aliran massa kebocoran), air flow rate atau ventilation rate berpengaruh terhadap besarnya distribusi kebocoran. Dari penelitian di tunjukan bahwa ketika terjadi kebocoran pada unit AC, pengaruh air flow rate dapat meningkatkan kadar difusi (dispersi) atau penyebaran gas akan tetapi setelah refrigeran habis maka pengaruh kecepatan kipas air flow (ventilasi rate) dapat meningkatkan pencampuran udara dan refrigeran dengan arti dilute atau menipiskan (mengurangkan) kadar refrigeran pada ruangan dan menurunkan kadar konsentrasi yang tertinggi pada suatu titik bagian ruangan. Laju kebocoran ditunjukan dalam hasil penelitian bahwa kebocoran sebagai fungsi waktu, semakin besar laju kebocoran dan semakin lama maka kadar distribusi konsentrasi semakin cepat terakumulasi dan berkumpul memenuhi sebuah ruangan. Perbedaan densitas berpengaruh terhadap kondisi terakumulasinya atau berkumpulnya refrigeran. Keywords: Prediksi, Refrigeran Flammable, Simulasi Numerik, CFD, buoyancy, densitas, laju kebocoran, air flow rate atau ventilation rate, Buoyant jet model

INVESTIGASI EKSPERIMENTAL PERFORMA SISTEM PENDINGIN MULTI-TERMOELEKTRIK DENGAN KONFIGURASI TERMAL SERI DAN PARALEL

Thermoelectrics can convert electrical energy to thermal energy. The generated thermal energy can be used in various cooling systems (TEC) applications. Improvement of TEC performance influenced by hot-side heat dissipation method, working fluid, and multi-thermoelectric. This study aims to investigate the relation between multi-thermoelectric configuration and the cooling behaviors. The experiment was conducted on the devices equipped with two modules of TEC arranged in series and parallel with variations of input voltage, working fluid mass flow, and temperature. The result reveals variations in cooling behaviors between the two configurations. Parallel configuration TEC gives the highest cooling capacity with a value of 66.62 W, 100% bigger than the series configuration. Meanwhile, the series configuration provides a delta temperature of 11.03 K, 2% higher than the parallel one. The parallel modules cooling performance is the biggest among the two arrangement, with a value of 2.57, which is 147% higher than series one

Numerical Study of Thermal Comfort Evaluation in Naturally Ventilated Classrooms

The classroom is one of the important facilities in teaching and learning activities. Just like any other room, ensuring thermal comfort becomes a vital aspect for its occupants. This study aims to evaluate environmental conditions and the thermal comfort experienced by classroom occupants through numerical methods. The evaluation involves the integration of the Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD) equations into Computational Fluid Dynamics (CFD) simulations using a user-defined function. Furthermore, extensive field measurements and questionnaire surveys are also employed to support the simulation process. The results indicate that the air temperature tends to be high, reaching 30.91°C. Meanwhile, the air velocity within the room, particularly in the occupied areas, is significantly low, with an average value of 0.04 m/s. According to the ASHRAE Standard 55, the classroom is perceived as uncomfortable, as evidenced by a PMV value of 1.38 and a PPD of 44.94%. Therefore, efforts are required to enhance the thermal comfort in the space

Energy and Exergy Analysis of Chest Freezer Using R134a and R290 as Working Fluids Based on Experimental Data

Although R134a has a very high global warming (GWP) effect, it is still used as a refrigerant in chest freezers. As an alternative to R134a is R290 which has a very low GWP value, which is only 3. Therefore, it is expected that there will be no more chest freezers using R134a and replaced with R290, soon. Thermodynamic studies need to be conducted to see the advantages and disadvantages of the two refrigerants based on experimental data. In this study, a chest freezer which was originally manufactured for R134a with a charging mass of 150 g was used as a test object. Experimental data of the chest freezer using R290 was taken after testing with R134a was completed. Experimentally, the cabin temperatures of the chest freezer using R134a and R290 are -20.5oC and -35.7oC, respectively, and the input power are 264 W and 176 W, respectively. Total irreversibility on the four main components of the chest freezer using R134a is greater than using R290, namely 184.4 W and 107.0 W, respectively. This means that the use of R290 as a working fluid in the chest freezer is more efficient. There are at least three advantages of replacing R134a with R290, namely reducing greenhouse gas emissions because R290's GWP is much smaller than R134a, lower cabin temperature, and decreasing the input power of the chest freezer

Effect of compressor-discharge-cooler heat-exchanger length using condensate water on the performance of a split-type air conditioner using R32 as working fluid

The utilization of condensate water as a compressor-discharge cooler results in subcooling on the condenser outlet. On the other hand, a split-type air conditioner (A/C) with R32 as working fluid can provide higher compressor-discharge temperatures than other refrigerants used in the same A/C. Therefore, A/C working with R32, equipped with a heat exchanger by utilizing waste-condensate water as the compressor-discharge cooler, has promising potential to produce the largest subcooling effect in air-conditioning systems. The aim of this study is to investigate the effect of condensate water as the compressor-discharge cooler on the performance of an A/C using R32 as the working fluid with different sizes of heat exchanger. The experimental study was carried out on the A/C with a compressor capacity of 1.1 kW, using three different heat-exchanger lengths, i.e., 18, 20 and 22 cm. The results indicated that longer heat exchangers produced higher degrees of sub-cooling; the heat exchangers with lengths of 18, 20 and 22 cm produced average degrees of subcooling of 0.9, 1.5 and 4.5 K, respectively. Therefore, increments in the degree of subcooling generate improvements in cooling capacity, lowering the compressor-input power, and enhance the COP of the A/C. The average COP improvement of the A/C with heat-exchanger lengths of 18, 20 and 22 cm were 9.1, 14.4 and 27.3%, respectively