• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.144-146
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• 1999

This paper provides an analysis of the effect of input signals, such as acceleration power and generator shaft speed for improving Power System Stabilizer(PSS) efficiency. We consider a single machine and infinite bus system which is modeled by PSCAD/EMTDC. We choose an optimum stabilizer gain with respect to eigenvalue analysis and transient stability analysis to each input signal.

• Agricultural and Biosystems Engineering
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• 제2권1호
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• pp.7-14
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• 2001

A rice mill plant with a capacity of 3 t/h was constructed with automated facilities at Chonnam National University. A simulation model was developed with SLAMSYSTEM for evaluation and improving the rice mill process. The developed model was validated in the views of hulling efficiency, milling efficiency, milled rice recovery, other materials produced, at bottlenecks in the processes. The results of hulling efficiency, milling efficiency, milled rice recovery in the simulation were, respectively, 81.1%, 89,5%, and 73.1%, while those of the actual mill plant were 81.5%, 90.2%, and 73.5%. The simulation results including the rates of other materials(chaff, bran, broken rice, stone, etc) produced in the processes were almost similar with those of the actual process. In the simulation the bottlenecks were found out in the process for separating brown rice and sorting colored rice. These phenomena also appeared in the actual process. It needed to increase the hourly capacities of the brown rice separator and the rice color sorter. As the developed model could well express the automated rice mill plant, it could be used for designing and improving rice mill plants.

• 한국농공학회지
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• 제16권2호
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• pp.3395-3409
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• 1974

The purpose of this study is to test and compare the efficiency of heating-system for materials and construction of the wall, ceiling and window in soil brick house, cement house and boulder house respectively, in order to construct ideal farm houses in rural area. The results obtained were as follows: 1. In heat conservation due to construction of walls the thermal efficiency of cement brick house was equivalent to 66.3% of that of soil brick house, and boulder house 60.3% 2. In the case of ceiling, the thermal efficiency of paper ceiling was amounted to 84.2% of that of the composite ceiling (thickness 6mm veneer+thickness. l0m chaffs), and the common ceiling putting on soil above the ceiling, 76% of the composite while the efficiency of the ceiling putting on chaffs above them was 15.8% higher than that of the paper. 3. In the case of improving the window, the double type was 12% higher than. the efficiency of single type. 4. The warming velocity of conventional house was slower but the velocity of radiation was quicker than that of experimental one. It was thought to be due to unscietific constructions of the room bottom, fire inlet and chimney, 5. The temperature gradient line was not dependad upon the amount of throwing into fuel in the rural farm house. 6. It was concluded that the final thermal efficiency of the conventional farm house was 10.6% lower than that of experimental farm house.

• 한국유기농업학회지
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• 제31권4호
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• pp.357-380
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• 2023

This study analyzed the management efficiency of jujube, bitter persimmon, and chestnut farms using data envelopment analysis (DEA). And this study analyzed causes affecting management inefficiency of those farms using the two-step method. The main findings are as follows. First, as self and employment labor costs are increased, it is important to reduce labor costs which account for 60~70% of the total production cost. Second, efforts to improve management efficiency are needed as overall efficiency of farms were decreased. Third, a pesticide cost per 10a representing a level of pesticide had a negative effect or did not have a statistically significant effect on the management efficiency. This implies that expanding environment-friendly production by reducing pesticides is effective for improving the management efficiency. Fourth, as leading farms were more efficient than general farms, technology dissemination and education through leading farms are important for improving efficiency, and efforts are needed to promote exchange between leading and general farms.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
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• pp.240-242
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• 2000

This study was investigated absorption properties of electromagnetic wave in thermal sprayed Sr-ferrite coatings. The experiment of this study was ; manufactured thermal spraying powder for improving absorption-efficiency, processed for increasing strength of thermal spray coatings, and measured the electromagnetic wave shielding efficiency. This study was obtained excellent absorption-efficiency by thermal sprayed Sr-ferrite coatings.

• 전자공학회논문지
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• 제52권3호
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• pp.59-66
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• 2015

본 논문에서는 4bit SAR-ADC(Successive Approximation ADC) 기반의 LDO(Low Drop-Out Regulator)와 파워 트랜지스터의 사이즈 선택을 통하여 DC-DC 벅 컨버터의 효율을 개선하는 방법을 제안한다. 제안하는 회로는 부하 전류에 따라서 파워 트랜지스터 사이즈를 선택하여 DC-DC 벅 컨버터의 효율을 개선한다. 이를 위해, 우리는 스위칭 손실과 전도 손실이 교차하는 지점을 파워 트랜지스터의 적절한 사이즈로 선택하였다. 또한, standby mode 또는 sleep mode로 동작 시에는 효율을 개선하기 위해 LDO로 동작하도록 하였다. 제안하는 회로는 4bit로 파워 트랜지스터 사이즈(X1, X2, X4, X8)를 선택하였고, 저부하에서 단일 사이즈를 이용한 기존의 방식보다 최대 25%의 효율 개선을 얻을 수 있었다. 입력 전압은 5V, 출력 전압은 3.3V, 최대 부하 전류는 500mA이다.

• 산업경영시스템학회지
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• 제30권2호
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• pp.67-74
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• 2007

The objective of this research is to select the most effective technique among task related techniques(motion & time study, job redesign, physical environment improvement) for improving work efficiency in shipbuilding enterprise. This study consists of several principal steps. The first step is to design critical criteria in evaluating work efficiency in ship-building enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP(Analytic Hierarchy Process) structure using the critical criteria, sub-criteria and techniques among task related techniques. The fourth step is to develop the pairwise comparison matrix at each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique among task related techniques using AHP analysis. The result of AHP analysis has shown clear difference in priority among task related techniques in terms of work efficiency of the shipbuilding enterprise: The reduction of normal time is more important than the reduction of allowance time in improving of the work efficiency. Motion & time study is the most important technique for the reduction of normal time, and physical environment improvement is the most important technique for the reduction of allowance time as well.

• 환경정책연구
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• 제8권4호
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• pp.37-49
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• 2009

90년대 이후 용수관리 정책이 공급중심에서 수요관리로 정책 전환이 되면서 공업용수 수요량이 급격히 감소하였다. 본 연구에서는 공업용수 사용의 기술적 효율성을 분석하여 이러한 공업용수 수요량 감소가 공업용수의 사용이 효율적으로 이루어진 결과인지 검토하고 향후 공업용수의 기술적 효율성 제고를 통하여 공업용수 사용량을 더 줄일 수 있는지 검토하였다. 본 연구결과에 의하면 공업용수의 기술적 효율성은 1998년도 0.5183에서 2003년도에는 0.4853으로 도리어 약간 감소한 것으로 나타났다. 이는 다른 투입요소의 기술적 효율성에 비하여 낮은 수치로 앞으로 기술적 효율성 제고를 통하여 공업용수 사용량을 더 절감할 수 있음을 보여준다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.81-82
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• 2006

Doping is a well-known method for improving electroluminescent (EL) efficiency of organic light emitting diodes. In our study, doping with 2 materials simultaneously, we could achieve improved EL efficiency. The emission layer was tris-(8-hydroxyquinoline)aluminum, and the 2 dopants were N,N'-dimethyl-quinacridone (DMQA) and 10-(2-Benzothiazolyl)-2, 3, 6, 7-tetrahydro-1,1,7,7,-tetramethyl 1-1H, 5H, 11H-[1] benzopyrano [6,7,8-ij]quinolizin-11-one (C-545T). The EL intensity of co-doped device was nearly flat, it shows that co-doping technique could be a effective way to improve the EL efficiency. EL efficiency of Single-doped device based on DMQA and C-S45T were ~6.47Cd/A and ~7.45Cd/A, respectively. Co-doped device showed higher EL efficiency of ~8.30Cd/A.

• 대한안전경영과학회지
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• 제5권3호
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• pp.99-106
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• 2003

This study concerns with an ergonomic approach for improving the workplace of an air-conditioner factory. If work tasks and equipments do not include ergonomic principles in their design, workers may have exposure to undue physical stress, strain, and overexertion, including awkward postures, forceful exertions, repetitive motion, and heavy lifting. The purpose of this study is to improve the safety, comfort, and efficiency of the workplace. Adapting tasks, work stations, tools, and equipments to fit the worker can help reduce physical stress on a worker's body and enhance the effectiveness and efficiency of workplace.