• 산업경영시스템학회지
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• 제38권2호
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• pp.145-151
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• 2015

As order quantity is increased, the ordering cost per item will be cheaper due to saving of transportation and material handling costs. In this paper, two realistic assumptions such as quantity discount and budget limit are considered. Quantity discount means that all units in the order will be discounted according to the predetermined order levels. Budget limit represents that the costs for inventory investments are bounded. This paper develops a Lagrangian relaxation approach for a continuous review inventory model with a budget constraint and quantity discounts. Computational results indicate that the proposed approach provides a good solution. Sensitivity analysis is done to get some insights on budget limit and quantity discount. As budget limit or the amount of discount according to order quantity is increased, order quantity is increased, whereas reorder point is not always increased.

• 반도체디스플레이기술학회지
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• 제9권2호
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• pp.21-25
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• 2010

In response to the industrial needs for automated handling of very thin solar cell wafers, this paper presents the design concept for the individual wafer separation from the stacked wafers by utilizing continuous water jet. The experimental apparatus for automated wafer separation was constructed and it includes the water jet system and the microprocessor controlled wafer stack advancing system. Through a series of tests, the performance of the proposed design is quantified into the success rate of single wafer separation and the rapidity of processing wafer stack. Also, the inclination angle of wafer equipped cartridge and the water jet flowrate are found to be important parameters to be considered for process optimization. The proposed design shows the concept for fast and efficient processing of wafer separation and can be implemented in the automated manufacturing of silicon based solar cell wafers.

• Smart Structures and Systems
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• 제13권3호
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• pp.419-434
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• 2014

In this paper, the electromagnetic damper (EMD), which is composed of a permanent-magnet rotary DC motor, a ball screw and a nut, is considered to be analyzed as a semi-active damper. The main objective pursued in the paper is to study the two degrees of freedom (DOF) model of the semi-active electromagnetic suspension system (SAEMSS) performance and energy regeneration controlled by on-off and continuous damping control strategies. The nonlinear equations of the SAEMSS must therefore be extracted. The effects of the EMD characteristics on ride comfort, handling performance and road holding for the passive electromagnetic suspension system (PEMSS) are first analyzed and damping control strategies effects on the SAEMSS performance and energy regeneration are investigated next. The results obtained from the simulation show that the SAEMSS provides better performance and more energy regeneration than the PEMSS. Moreover, the results reveal that the on-off hybrid control strategy leads to better performance in comparison with the continuous skyhook control strategy, however, the energy regeneration of the continuous skyhook control strategy is more than that of the on-off hybrid control strategy (except for on-off skyhook control strategy).

• Journal of Ship and Ocean Technology
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• 제9권4호
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• pp.35-46
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• 2005

The performance of optimisation methods, based on penalty functions, is highly problem- dependent and many methods require additional tuning of some variables. This additional tuning is the influences of penalty coefficient, which depend strongly on the degree of constraint violation. Moreover, Binary-coded Genetic Algorithm (BGA) meets certain difficulties when dealing with continuous and/or discrete search spaces with large dimensions. With the above reasons, Real-coded Micro-Genetic Algorithm (R$\mu$GA) is proposed to find the global optimum of continuous and/or discrete nonlinear constrained engineering problems without handling any of penalty functions. R$\mu$GA can help in avoiding the premature convergence and search for global solution-spaces, because of its wide spread applicability, global perspective and inherent parallelism. The proposed R$\mu$GA approach has been demonstrated by solving three different engineering design problems. From the simulation results, it has been concluded that R$\mu$GA is an effective global optimisation tool for solving continuous and/or discrete nonlinear constrained real­world optimisation problems.

• 유통과학연구
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• 제13권1호
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• pp.83-91
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• 2015

Purpose - Despite the structural irrationality of multi-level transportation and the oil price rise, the domestic freight transportation market continues to grow, mirroring the rise in e-commerce and resultant increase in courier services and freight volumes. Several studies on courier services have been conducted. However, few studies or statistics have been published regarding regular freight services although they have played a role in the freight service market. The present study identifies the characteristics of regular freight service users to seek competitiveness enhancement measures specific to regular freight services. Research design, data, and methodology - IPA is a comparative analysis of the relative importance of and satisfaction with each attribute simultaneously. This study used IPA because it facilitates the process of analyzing importance and performance, deriving implications and a visual understanding of results. To enhance the competitiveness of regular freight services, this study surveyed its current users regarding the importance of the regular freight service factors. A total of 200 copies of a questionnaire were circulated and 190 copies were returned. In addition to demographics, respondents answered questions about the importance of and satisfaction with services on a 5-point Likert scale. Excluding 3 inappropriate copies, 187 out of 190 copies were analyzed. PASW Statistics 18 was used for statistical analysis. A total of 20 question items were selected for the service factors presented in the questionnaire based on the 1st pilot survey and previous studies. Results - According to the IPA performed to compare the importance of and satisfaction with service factors, both importance and satisfaction are high in the 1st quadrant, which involves the economic advantage of using regular freight services, quick arrival at destinations, weight freight handling, and less time constraints on freight receipt/dispatch. This area requires continuous management. Satisfaction is higher than importance in the 2nd quadrant, which involves the adequacy of freight, cost savings over ordinary courier services, notification on freight arrival, and freight tracking information. This area requires intensive investment and management. Satisfaction is lower than importance in the 3rd quadrant, involving the credit card payment system, courier delivery service, distance to freight handling sites, easy access to freight handling sites, and prompt problem solving. This area requires further intensive management. Both importance and satisfaction are low in the 4th quadrant, involving the availability of collection service, storage space at freight handling sites, kindness of collection/delivery staff, kindness of outlet staff, and easy delivery checks. This area is a set of variables should be excluded from priority control targets. Conclusions - Based on the IPA, service factors that need priority controls because of high importance and low satisfaction include the credit card payment system, delivery service, distance to freight handling sites, easy access to freight handling sites, and prompt problem solving. The findings need to be applied to future marketing strategies for regular freight services and for developing competitiveness enhancement programs.

• 한국전문물리치료학회지
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• 제4권1호
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• pp.11-19
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• 1997

The use of therapeutic ultrasound(US) in humans with malignant neoplasms has been contraindicated in physical therapy practice. Some studies have shown that results after application of US differ according to tumor type and penetration depth. The purposes of this study were to determine the effects of US on melanoma in mice and to determine treatment dosage. Twenty-four female C57BL/6 mice, age 8 weeks. The right flank of all mice was shaved, and a 0.1 ml suspension of cells was injected subcutaneously into the animals' right flank. In this study, 24 subjects were randomly divided into three groups: experimental group 1(n=8), experimental group 2(n=8), control group(n=8). In the experimental group 1, animals received continuous 3 MHZ US treatment, administered at $2.0W/cm^2$ for five minutes. In experimental group 2, animals received continuous 3 MHz US treatment, administered at $1.0W/cm^2$ for 5 minutes. The control group received the same handling as other experimental groups, including rodent chow, water, US gel application but US head pressure without the power turned on. After 10 days treatment, all mice were killed with a potassium solution. Tumors were excised and weighed on an electrical balance and fixed in a 10% neutral buffered formalin solution. Tumor weights were smaller in experimental group 2(0.3838 g) than in the control group(0.6275 g). Tumor weights of the experimental group 1(0.015 g) were smaller than those of experimental group 2. Continuous therapeutic US decreased the weight of subcutaneous melanoma tumors in mice. The treatment dosage($2.0W/cm^2$) we suggest was more effective than earlier studies on decreasing tumor size with ultrasound.

• 한국항해항만학회지
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• 제32권8호
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• pp.621-628
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• 2008

지속적인 컨테이너 물동량의 증가와 컨테이너선의 대형화에 따라서 항만간의 경쟁은 점점 치열해지고 있다. 주요 항만 하역장비 제조사들은 획기적인 생산성 향상을 제공할 수 있는 새로운 개념의 하역장비 개발에 많은 관심을 기울이고 있다. 본 연구에서는 항만의 대표적 하역장비인 컨테이너 크레인에 대해서 다양한 개발 대안들이 존재할 때, 최적의 개발 대안을 선정하는 절차를 제시한다. 절차는 두 단계로 구성되는데, 첫 번째 단계에서는 요구되는 필수요소들을 만족하지 못하는 대안을 제거하고 두 번째 단계에서는 전문가의 평가와 선형 할당법을 적용하여 최종적인 개발 대안을 선정한다. 마지막으로, 제시한 절차를 적용한 사례를 제시한다.

• 대한안전경영과학회지
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• 제16권3호
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• pp.101-110
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• 2014

This study tried to identify the effects of ergonomic risk factors for absence from work of fire fighters in Korea. A self-administered questionnaire was prepared for this study. The questionnaire consisted of several parts such as 'general information', 'work-related factors', 'physical & chemical risk factors', 'ergonomic risk factors', and 'absence information'. A total of 7,098 fire fighters participated in this study. The data obtained from the survey was mainly analyzed by logistic regression. A total of 856 out of 7,098 fire fighters experienced absence from work. The risk factors such as gender, age, marital status, education level, total work year, work area. position, job rotation, noise, dust, organic solvent, skin contact with chemical substance, toxic waste, regional vibration, manual material handling, continuous standing posture, awkward working posture were associated with absence from work. Specifically, awkward working posture and manual material handling from ergonomic risk factors were major risk factors for absence from work.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제8권1호
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• pp.11-17
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• 2008

Typical wireless sensor networks used in structural monitoring are continuous types wherein data transmission is progressive at all time that may include irrelevant and insignificant data and information. Continuous types of wireless monitoring systems often pose problems of handling large-sized data that may deteriorate the performance of the system. The proposed method is to suggest an event-triggered monitoring system that captures and transmits relevant data only. An error signal generated by the Principal Components Analysis (PCA) is utilized as an index for event detection and selective data transmission. With this new monitoring scheme, the remote server is relieved of unwanted data by receiving only relevant information from the wireless sensor networks. The performance of the proposed scheme was verified with simulation studies.

• 한국융합학회논문지
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• 제8권11호
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• pp.103-108
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• 2017

유비쿼터스 환경에서는 다양한 센서로 부터 원거리에 데이터를 전송해야 하는 문제가 제기되어져 왔다. 특히 서로 다른 위치에서 도착한 데이터를 통합하는 과정에서 데이터의 속성 값들이 상이하거나 데이터에 일부 손실이 있는 데이터들도 처리해야 하는 어려운 문제를 가지고 있었다. 본 논문은 이와 같은 데이터들을 대상으로 집락분석 하는 방법을 제시한다. 이 방법의 핵심은 문제에 적합한 목적함수를 정의하고, 이 목적함수를 최적화 할 수 있는 알고리즘을 개발하는데 있다. 목적함수는 OCS 목적함수를 변형하여 사용한다. 이진 값을 가지는 데이터만을 처리할 수 있었던 MFA(Mean Field Annealing)을 연속 값을 가지는 분야에도 적용할 수 있도록 확장한다. 그리고 이를 CMFA이라 명하고 최적화 알고리즘으로 사용한다.