• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.III
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• pp.819-826
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• 2000

This study was performed to develop a measurement system of tractor field performance for plow and rotary operations. Measurement system for tractor consisted of torque sensors to measure torque of drive axles and PTO axle, speed sensors to measure rotational speed of drive axles and engine, microcomputer to control data logger, and data logger as I/O interface system. The measurement system was installed on four-wheel-drive tractor. Four-element full-bridge type strain gages were used for torque measurement of drive axles and optical encoders were used to measure speeds of drive axles and engine. Slip rings were mounted on the rotational axles. Signals from sensors were inputted to data logger that was controlled by microcomputer with parallel communication. Sensors were calibrated before the field tests. Regression equations were found on completion of the calibrations. The field experiment was performed at paddy fields and uplands. Rotary and plow were used when the tractor was operated in the field. Travelling speeds of the tractor were 1.9 km/h, 2.7 km/h, 3.7 km/h, 5.5 km/h, 8.2 km/h, and 11.8 km/h. Operating depths of implements were maintained approximately 20cm during the tests. Torque data of drive axles were different at each location during plow and rotary operations. Results showed that torque of rear axles were greater than those of front axles. Total torque were 6860 - 11064 Nm at the upland and 7360 - 14190 Nm at the paddy field for plow operations. It was found that torque at the paddy field were about 20% greater than those at the upland for plow operations. Torque data showed that rotary operations required less power than plow operation at the paddy field and the upland. Torque measurements at each axle for rotary operations were only 8 - 16% of plow operations in the upland and 15 - 20% in the paddy field.

• 한국경영과학회지
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• 제17권2호
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• pp.35-43
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• 1992

In this paper fuzzy ranking method using dominance relation is suggested. This method is compared to the existing fuzzy number comparing methods. All ten methods with the suggested method are evaluated using six example based on four criteria.

• 한국수학사학회지
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• 제14권2호
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• pp.1-12
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• 2001

Considering the four arithmetical operations, the operations over some problems in the second half periods of Chosun Dynasty were dealt in the different dimensions were not reasonable and tile units of the dimensions were neglected. This paper aims to introduce some questionable solved problems related to tile equations higher than tile second degree.

• 한국국방경영분석학회지
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• 제12권1호
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• pp.16-37
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• 1986

This paper first examines the importance of SLOC from the Korean standpoint, second conducts general survey for SLOC protection strategies of four major powers, US, USSR, China and Japan, third analyzes the surrounding sea lane environments, and finally derives optimum protection strategy for ROK SLOC, a 'life line'.

• 한국경영과학회지
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• 제35권2호
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• pp.1-17
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• 2010

This paper aims to compare four operating priority rules of RMGC (Rail Mounted Gantry Crane) used in semi-automated container terminal. The four priority rules employed in this paper are FCFS (First-come-first-served), LCFS (Last-come-first-served), TOS (Turn-over-served) and NFS (Nearest-first-served). And to compare the four operating priority rules, this paper analyzed productivity of RMGC and CC (Container Crane), waiting time of YT (Yard Truck) and RT (Road Truck) in container yard, and turnaround time of RT in container terminal of each priority rule by using stevedoring simulation. As a result, NFS was evaluated as the best rule to improve the overall productivity of container terminal in terms of all criteria.

• 한국경영과학회지
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• 제27권4호
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• pp.149-165
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• 2002

This study establishes key factors on ISM (Internet Shopping Mall) performance in Korea. The four factors are derived from the relevant literature and clarified the concept of ISM characteristics, customer characteristics, ISM evaluation level. and perceived risks by distinguishing between its components and determinants. ISM performance indicators were derived from the previous studios classifying by ISM attitude and ISM usage. We examine on the impact of ISM characteristics and customer characteristics on the ISM evaluation level, then its level and perceived risks on the ISM performance. Hypotheses on four factors of ISM performance were tested for 172 respondents. Results indicate that four factors may partially serve as key predictors on ISM performance. ISM characteristics and customer characteristics was found to be positively influenced on ISM evaluation level, and its level also positively affected on ISM performance while perceived risks negatively affected on ISM performance.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.294-303
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• 2016

Purpose: This study aimed to evaluate the profitability of four selective mechanization systems in rice cultivation. Methods: Field experiments were conducted in the farmers' field during the wet season (June to November) of 2015 in Bangladesh. Mechanization systems were applied to evaluate four different selective levels (treatment) in eleven consequent operations. Seedlings were raised in a traditional seedbed and trays for manual and mechanical transplanting, respectively. Land preparation, irrigation, fertilizer, pesticide, carrying, and threshing and cleaning operations were performed using the same method in all the experimental plots. The mechanical options in the transplanting, weeding, and harvesting operations were changed. The mechanization systems were $S_1$ = hand transplanting + hand weeding + harvesting by sickle, $S_2$ = mechanical transplanting + Bangladesh Rice Research Institute (BRRI) weeder + reaper, $S_3$ = mechanical transplanting + BRRI power weeder + reaper, and $S_4$ = mechanical transplanting + herbicide + reaper. This experiment was performed in a randomized complete block design with four replications. Power tiller, rice transplanter, BRRI weeder, BRRI power weeder, self-propelled reaper, BRRI open drum thresher, and BRRI winnower were used in the respective operations. Accordingly, the techno-economic performances of the different technologies were calculated and compared with those of the traditional system. Results: The mechanically transplanted plot produced 6-10% more yield than the hand transplanted plot because of the use of tender-aged seedlings. Mechanical transplanting reduced 61% labor and 18% cost compared to manual transplanting. The BRRI weeder, BRRI power weeder, and herbicide application reduced 74, 91, and 98% labor, respectively. The latter also saved 72, 63, and 82% cost, respectively, compared to hand weeding. Herbicide application reduced the substantial amount of labor and cost in the weeding operation. Mechanical harvesting also saved 96% labor and 72% cost compared to the traditional method of harvesting using sickle. Selective mechanization saved 15-17% input cost compared to the traditional method of rice cultivation. Conclusions: Mechanical transplanting with the safe use of herbicide and harvesting by reaper is the most cost- and labor-saving operation. The method might be the recommended set of selective mechanization for enhancing productivity.

• 대한전자공학회논문지SD
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• 제45권9호
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• pp.103-109
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• 2008

본 논문은 H.264 디코더용 인트라 예측 회로 구조와 설계를 제시한다. H.264의 인트라 예측에는 총 17개의 예측 모드, 즉 루마 $4\times4$ 블록을 위한 9개의 예측 모드, 루마 $16\times16$ 블록을 위한 4개의 예측 모드, 크로마 $8\times8$ 블록을 위한 4개의 예측 모드가 있다 모든 예측 모드에서 공통된 연산들을 추출하여 이들을 수행하기 위한 공통연산부를 정의하였다. 모든 예측 모드에서 이 연산부를 공유하는 제안된 회로 구조는 설계 측면에서 체계적이고 회로 크기 측면에서 효율적이다.

• 한국초등수학교육학회지
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• 제21권3호
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• pp.531-546
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• 2017

본 연구에서는 계산 순서를 지도하는데 유용한 교수법적 내용 지식을 제공하기 위해 사칙계산 사이의 우선권은 어떠한 근거로 결정되었는지 살펴보고, 계산 순서를 바라보는 입장에 관해 논의하였다. 이러한 논의 결과를 바탕으로 다음 다섯 가지 제언을 결론으로 제시한다. 첫째, 교사들에게 덧셈과 뺄셈의 혼합계산 및 곱셈과 나눗셈의 혼합계산의 경우, 각각 뺄셈과 나눗셈부터 계산해도 동일한 계산 결과를 구할 수 있다는 것을 확인하는 기회를 제공할 필요가 있다. 둘째, 교사들에게 식의 왼쪽부터 차례대로 계산하는 규칙이 관습으로 자리 잡은 이유에 관해 논의할 수 있는 기회를 제공할 필요가 있다. 셋째, 교사들에게 덧셈과 곱셈의 혼합계산에서 곱셈이 덧셈보다 우선한다는 규칙 설정의 동인을 설명해 보는 기회를 제공할 필요가 있다. 넷째, 교사들에게 괄호가 있는 식에서 하나의 수량이라는 괄호의 의미를 강조할 필요가 있다. 다섯째, 교사용 지도서에서 계산 순서의 입장을 기술할 때는 계산 순서의 관습적, 개념적 입장을 모두 기술하여 교사들의 계산 순서에 대한 이해를 심화시킬 필요가 있다.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.487-493
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• 2004

This paper consider a six sigma project for improving the TIP life time in a spot welding process. The project follows a disciplined process of five phases: define, measure, analyze, improve, and control. A process map is used to identify process input and output variables. Nine key process input variables are selected by using C&E matrix and FMEA, and finally four vital few input variables are selected from analyze phase. The optimum process conditions of the four vital few input variables are jointly obtained by maximizing TIP life time using DOE.