• 대한안전경영과학회지
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• 제11권3호
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• pp.209-216
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• 2009

A development in method of evaluating the measurement precisions using approximate F tests and variance components from expected mean square (EMS) is investigated. The research proposes three-factor mixed measurement models with the fixed and random factors. Unrestricted and unconstrained design work was rarely studied, while restricted and constrained designs have been significantly discussed. The unrestricted and unconstrained designs assume to be an independence of interaction. The proposed evaluation method about the measurement precisions can be extended to four-factor random measurement model or mixed measurement model. The study also presents the three evaluation indexes of precisions such as R&RTR (Reproducibility & Repeatability-To-Total Precision Ratio), PTR (Precision-To-Tolerance Ratio), and SNR (Signal-To-Noise Ratio). Numerical examples are proposed to evaluate the approximate F tests with Satterthwaite degrees of freedom and three indexes using the measurement precisions from EMS.

• 드라이브 ㆍ 컨트롤
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• 제9권3호
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• pp.29-36
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• 2012

The hydraulic cylinder is used for actuating the roller-link type rotating floodgate which controls the volume of water in the reservoir. The locating points of hydraulic cylinder are restricted to the limited space and determined to minimize the cylinder force necessary for actuating the floodgate. Generally, the head end point of cylinder is fixed at underground and the rod end point of cylinder is connected to the support link. Therefore there exist three design variables to be determined to minimize the cylinder force within the rotating range of floodgate. First, the mathematical model of the roller-link type rotating floodgate is derived to find the cylinder force corresponding to the floodgate angle. Then, the optimal locating point of hydraulic cylinder is searched using the complex method that is one kind of constrained direct search method.

• 디지털산업정보학회논문지
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• 제19권3호
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• pp.245-251
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• 2023

Facial expression recognition plays a significant role in understanding human emotional states. With the advancement of AI and computer vision technologies, extensive research has been conducted in various fields, including improving customer service, medical diagnosis, and assessing learners' understanding in education. In this study, we develop a model that can infer emotions in real-time from a webcam using transfer learning with TensorFlow.js and MobileNet. While existing studies focus on achieving high accuracy using deep learning models, these models often require substantial resources due to their complex structure and computational demands. Consequently, there is a growing interest in developing lightweight deep learning models and transfer learning methods for restricted environments such as web browsers and edge devices. By employing MobileNet as the base model and performing transfer learning, our study develops a deep learning transfer model utilizing JavaScript-based TensorFlow.js, which can predict emotions in real-time using facial input from a webcam. This transfer model provides a foundation for implementing facial expression recognition in resource-constrained environments such as web and mobile applications, enabling its application in various industries.

• 한국자동차공학회논문집
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• 제9권1호
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• pp.122-130
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• 2001

In order to improve the efficiency of the design process and the quality of the resulting design, this study proposes a design method for determining design variables of an automotive wheel-bearing unit of double-row angular-contact ball bearing type by using a genetic algorithm. The desired performance of the wheel-bearing unit is to maximize system life while satisfying geometrical and operational constraints without enlarging mounting spae. The use of gradient-based optimization methods for the design of the unit is restricted because this design problem is characterized by the presence of discrete design variables such as the number of balls and standard ball diameter. Therefore, the design problem of rolling element bearings is a constrained discrete optimization problem. A genetic algorithm using real coding and dynamic mutation rate is used to efficiently find the optimum discrete design values. To effectively deal with the design constraints, a ranking method is suggested for constructing a fitness function in the genetic algorithm. A computer program is developed and applied to the design of a real wheel-bearing unit model to evaluate the proposed design method. Optimum design results demonstrate the effectiveness of the design method suggested in this study by showing that the system life of an optimally designed wheel-bearing unit is enhanced in comparison with that of the current design without any constraint violations.

• 대한토목학회논문집
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• 제12권3호
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• pp.139-151
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• 1992

유입량의 분포에 따른 가변(可變) 제한수위(制限水位)아래서 홍수기(洪水期) 저수지 이수운영(利水運營)모형을 수립하였다. 사용된 최적화모형은 방류량(放流量)의 기대방류량(期待放流量)으로부터의 편차를 최소화하는 모형과 홍수조절용량을 최소화하는 위험도제약(危險度制約) 선형계획법(線形計劃法)(CCLP)모형(模型)의 2가지 부모형(副模型)으로 구성되어 있다. 확정론적 등가식을 만들기위해 유입량의 분포는 2모수(母數) 대수정규분포(對數正規分布)를 가정하였으며 모수(母數)는 최우추정법(最尤推定法)에 의하여 구하였다. 모형은 소양강(昭陽江)댐과 충주(忠州)댐의 홍수기 운계운영(運繫運營)에 적용되었다. 그 결과 소양(昭陽)이 충주(忠州)보다 상대적으로 큰 규모의 홍수사상에 대하여 설계되었음을 알 수 있었다. 가변제한수위(可變制限水位)를 이용한 운영은 일률제한수위(一律制限水位)의 운영보다 효율적인 것으로 나타나는데 이는 충주(忠州)에서 더욱 두드러졌다, 유입홍수량이 큰 시구간의 방류형태는 홍수량의 규모를 줄이는 조절효과와 지체효과를 보이며, 갈수시에는 상대적으로 실제보다 많은 방류를 하는 형태를 보인다.

• 농업과학연구
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• 제24권1호
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• pp.94-107
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• 1997

Producing organic farm products is one of the high-payoff farming practices considering the rapid increase of consumer's purchasing power. The purpose of this study is to identify the optimal organic farming system in relation to farm income. To cope with the above objectives, present farming conditions and profitability of 15 farmers producing organic products including rice and leaf vegetables as lettuse and cabbage were surveyed in Hongsung and Ahsan Gun, Chungnam Province. Based on the surveyed data, maximization of organic farm income were analyzed under the constrained conditions such as limited monthly labour inputs and competitive use of land by Linear Programming Model. The results of this study can be summarized as follows. 1. In the profitability analysis of 15 farmers producing organic products, rice farmers could earn their farm income more than that of conventional farmers by 50%. On the other hand, the controlled lettuce farmers could get more about 100% than that of it. But the controlled cabbage farm could get more about 40% of it. These organic farm products were saled at high prices comparing with the prices of conventional farm products by 170% ~ 230% even though the crop yields produced by organic materials had decreased. 2. According to the labor requirement of the organically produced crops, rice cultivation was needed more labour inputs than the conventional farming method by 130%. On the other hand lettuce and cabbage could saved labour requirement by 40% and 80% of those respectively. Especially for the rice cultivation concern, higher labor requirement was due to the activities as organic fertilization, soil preparation and pest and weed controll, etc. 3. With the surveyed data from farmers who produced farm commodities, L.P. analysis was implemented to find out the optimul farming system and the maximum income. According to the results of L.P. analysis, 58% of total farm income could get more than the conventional farming system In the case of rice cultivation, one ha of paddy was recommendable to save more labour inputs than the controlled leaf vegetables such as lettuse and cabbage. However, in the controlled leaf vegatables, only 73% of total upland equivalent to 0.3 ha should be cultivated under the condition of labor shortage as the restricted 4 workers. And increasing the size of hogs raising should be recommened to achieve self-sufficiency of organic fertilizer. As pointed out the possibility of organic farming, present farmers producing organic farm products could be able to maximize their income by expanding organic farm size with regard to all conditions of our organic industry. Of course, there are many difficulties in the course of developing organic agriculture. So Government should effort to support the development of our organic agriculture considering the various aspects of production, marketing, Quality certification of organic produces.

• 대한지리학회지
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• 제47권2호
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• pp.159-178
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• 2012

백두산의 현재 지형은 반복적인 화산활동과 함께 신생대 제4기 기후변화로 추동된 빙하 활동의 결과물이다. 그러나 여전히 백두산 빙하지형의 존재에 대한 의문들은 해소되지 못해왔다. 이에, 본 연구에서는 야외조사를 통하여, 빙하지형에 관련된 지형들을 제시하고, 이의 연대측정을 실시하였으며, 제4기 화산 활동과의 관련성을 살펴보았다. 가속기 질량 분석기를 이용하여 빙하의 후퇴 이후 지표면에 노출되었을 백두산 천지 서사면의 빙하 기반암 지형 면에 대하여, 우주선 유발 동위원소 $^{36}Cl$의 농도를 측정하여 46~26ka의 표면노출연대를 얻었으며, 이는 적어도 천지 서쪽 사면은 지난 최종빙기 이후의 화산활동에 영향을 받지 않은 것을 지시하며, 특히 대략 천 년 전에 있었다고 보고되는 폭발성 분화에도 영향을 거의 받지 않았을 가능성이 매우 높다. 또한, 화산 쇄설물의 비대칭적 퇴적을 고려했을 때, 계절적으로 이 분화는 북서풍이 탁월한 겨울철에 발생한 것으로 사료된다. 빙하지형과 이의 연대 결과를 바탕으로 지형 발달과정을 복원해보면, 백두산의 빙하 지형은 지난 빙기까지 곡빙하(valley glacier)들이 연합한 빙모(ice cap) 형태에서 고립된 곡빙하를 거쳐 화산체 내부의 소규모 권곡(cirque) 형태로 변화한 것으로 추론된다.

• 마케팅과학연구
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• 제17권2호
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• pp.31-54
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• 2007

첨단산업의 기업들은 환경의 변화에 효과적으로 대응하는 것을 기업 성패에 중요한 요인으로 여기고 있다. 하지만 첨단산업의 환경 동태성이 공급체인 구성원 간 관계 결속에 미치는 영향에 관한 연구가 부족하여, 환경 변화에 효과적인 대응을 어렵게 하고 있다. 본 연구는 첨단산업에서 환경 동태성이 공급체인의 결속에 영향을 미치는 메커니즘에 대해 규명하고 있다. 좀 더 구체적으로 말하면, 첫째, 첨단산업의 고객, 경쟁, 기술 동태성이 공급체인의 결속에 어떠한 영향을 미치는지, 둘째, 공급체인의 유연성과 의존성이 이러한 영향에 어떠한 조절효과를 가지는 지 실증하고 있다. 구조방정식 모형에 의한 가설검정 결과 첨단산업의 고객 동태성은 공급체인의 결속을 약화시켰지만 경쟁 동태성은 강화시키는 역할을 하였다. 한편 유연성과 의존성은 고객과 경쟁 동태성에 유의적인 조절 효과를 가졌다.