• 산업경영시스템학회지
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• 제17권30호
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• pp.43-50
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• 1994

Work environment has been changed as the development of new techknowledge such as computer industry. The more new techknowledges, the more changes in our work conditions. But our cognitive limits can't pace up to the change of work environment. As a result, rapid work transfer occurs frequently, which increase work stress, work error and deleterous work performance. For many changes, this paper analyse the effect of work performance when the information used in mental work is changed as a sudden impact during dexterous work conditions. When the information impact is intruded in works, performances are reduced, but the react time does not respond sensitively then cognitive process time. So it is recommended to refer the cognitive time as a index of performance when mental work is included.

• 대한안전경영과학회지
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• 제13권3호
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• pp.97-105
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• 2011

In order to determine home delivery service routes, conditions specified for each parcel such as customer-assigned delivery times and parcel contents should be considered, so the conventional route search algorithms have some limits to be applied for home delivery services. In this study, a multi-purpose route searching algorithm is suggested in order to deal with every requirement of deliveries that vary in delivery distances, contents and appointed times. A simulation study to verify the performances of the system with example data of Seoul and Kyungki provinces shows that it significantly improves the customer satisfaction and the productivity of delivery businesses.

• 대한산업공학회지
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• 제24권3호
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• pp.333-343
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• 1998

This paper proposes variable stream and sample size(VSSS) group control charts in which both the number of streams selected for sampling and sample size from each of the selected streams are allowed to vary based on the values of the preceding sample statistics. The proposed charts select a small portion of streams and take samples of size n = 1 if both the largest and smallest of sample means fall between the lower and upper threshold limits, and select a large portion of streams and take samples of size n > 1 otherwise. A Markov chain approach is used to derive the formulas for evaluating the performances of the proposed charts. Numerical comparisons are made between the VSSS and fixed stream and sample size(FSSS) group control charts.

• Bulletin of the Korean Chemical Society
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• 제16권11호
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• pp.1023-1027
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• 1995

A comparative study of different torches in the Microwave Induced Plasma is reported. Three types of torches that have been used in this area are characterized and compared with each other. Especially, recently developed laminar flow torches have been optimized in design and analytical performances. The ratio of inner to outer tubes is found to be the most important parameter. As inner tube size increases, recirculating region also increases and consequently, sensitivity becomes better. An optimized laminar flow torch has been coupled to a gas chromatography and examined for halogen compounds. Detection limits are 25 pg s-1 for Cl and 12 pg s-1 for Br. These values are improved over the conventional laminar flow torch.

• Architectural research
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• 제24권2호
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• pp.53-61
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• 2022

Irregularities in the structure are crucial factors in screening structural vulnerability under extreme loadings. Numerical analyses were carried out considering wind and seismic loadings for four structures with discrete irregularity: continuous and discontinuous beams with varied story levels, and L-shaped irregular buildings. Structural responses such as maximum displacements, bending moments, axial forces, torsions, and story drifts are evaluated as per the criteria and limits defined by ACI 318. The outcomes indicate that the frame system with beam discontinuity on the upper half of the height exhibits the best structural performance. The results also indicate that the asymmetrical design of the L-shaped model makes it more susceptible to damage when subjected to strong lateral loading conditions.

• 통상정보연구
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• 제19권4호
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• pp.53-74
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• 2017

글로벌 무한경쟁의 시대에서 한국 상품의 경쟁력 하락에 대한 우려의 목소리가 높아지고 있다. 또한 서비스 분야의 미흡한 경쟁력 제고가 필요하다는 해묵은 지적이 있다. 그러나 정작 서비스 분야의 경쟁력 제고를 위한 노력과 성과는 찾아보기 어렵다. 그 원인의 하나는 서비스 분야의 영역이 분할되고 포획시장이 존재함으로써 이해관계를 가진 각 전문가 그룹이 시장의 해체 또는 규제 완화에 대하여 찬성하지 않기 때문이라고 할 수 있다. 이 연구는 이종자격사간의 동업(MDP)을 허용, 경쟁을 촉진하면 전문 서비스 분야의 경쟁력이 제고될 수 있다는 전제에서 출발하고 있다. 논리적 추론을 위하여 이종자격사간 동업이 허용될 경우 서비스의 가격이 낮아지고 서비스의 공급량이 많아진다는 이론적 분석결과를 도출하였고 MDP를 시행중인 주요국의 사례를 제시하고 있다. 아울러 관련 실증분석을 수행하였다. 잠정적인 결론으로 우선 문제의 소지가 비교적 작은 조세 법률 회계 분야에서 MDP를 도입하고 중장기적으로 다른 분야에까지 MDP를 확대할 것을 제안한다. 이 연구에는 여러 한계가 있다. 국제경제학 이외에 세무, 법률, 회계 분야에 대한 소양이 충분치 못하였고 관련 기업들의 경영 성과 지표 확보도 용이치 않았다. 아울러 실증분석에서 통제변수들을 분별해 내는 것도 쉽지 않았음을 밝혀 둔다. 그러나 잠정적인 결론이 변하지 않을 것으로 믿고 있다.

• 대한토목학회논문집
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• 제32권6D호
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• pp.579-586
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• 2012

본 연구의 목적은 장경간 강바닥판 교량의 교면포장 재료로서 에폭시 아스팔트 혼합물을 평가하고, 현장에 적용하는 것에 있다. 에폭시 아스팔트 혼합물의 국내 적용을 위한 골재입도를 제시하였고, 실내 공용성 실험을 수행한 결과 내구성능 면에서 매우 우수함을 알 수 있었다. 또한, 온도에 따른 회복탄성계수와 전단부착강도 시험결과를 활용하여 구조해석을 실시 후 전단응력 검토결과 전단부착강도의 9%로도 충분한 접착 성능을 확보할 수 있는 것으로 나타났다. 에폭시 아스팔트 교면 포장에 발생하는 인장응력의 경우 중국에 시공되어 검증된 난징대교 실내시험결과와 비교 시 유사하거나 작은 값을 나타내어 충분한 공용 성능을 확보할 수 있는 것으로 나타났다. 결과적으로 에폭시 아스팔트 혼합물은 일반 아스팔트에 비해 매우 우수한 내구성능을 확보할 수 있는 것으로 나타났다. 하지만 현장에서 장경간 강바닥판 교량의 교면포장 재료로서 에폭시 아스팔트 혼합물을 적용할 경우 온도와 양생기간에 따른 강도발현에 차이가 있을 수 있으므로 현장 적용 시, 생산 시료로 제작한 혼합물에 대한 평가가 이루어져야 한다.

• 한국수정란이식학회지
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• 제29권2호
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• pp.189-194
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• 2014

The reproductive disorders are the major causes of reproductive infertility in cows that affect the total annual calf crop, resulting in great economic loss in Bangladesh. The aim of the study was to find out the reproductive disorders (RD) in dairy cows that markedly influences the reproductive performances in aspect of Bangladesh. A total number of 1658 dairy cows were selected according to their body condition score (BCS) in different farms at the southern part of Bangladesh during the period of 2011 to 2012. The preliminary data (basic information) were collected directly from the dairy farmer's record books and asking questions according to a prescribed questionnaires as well as the diagnosis of RD was presumptively confirmed on the basis of history, clinical signs and examination of animals by ultrasonography and others necessary tools. There are thirteen major reproductive disorders were identified. Overall prevalence of reproductive disorders at that area were 23%, among of these anoestrus 5.1%, repeat breeder 3.7%, metritis 4.4%, poor heat detection 1.6%, ovarian cyst 0.36%, retain placenta 4.6%, dystocia 0.97% and pyometra 0.24%. It is indicated that anoestrus and retention of placenta after calving was most hazardous cause of infertility whereas the metritis and repeat breeder were the second line of consequence. RD had shown significantly higher incidence in low BCS (${\leq}2$) than that of fair (2.5) and very good (${\geq}3{\sim}3.5$). In conclusion, the highest RD especially anoestrus and retention of placenta is very alarming for reproductive loss which might be needed further research to identify the specific cause of these disorders for establishment a profitable dairying and dairy population.

• 한국기계가공학회지
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• 제15권4호
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• pp.125-133
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• 2016

From the first application of a thermoelectric module to nowtoday, it has been more than half a century. The application of a thermoelectric module is becoming more and more widely accepted since, people's requirement rely more and more on the efficiency of thermoelectric modules and their reliability become higher and higher. So people pay more and more attention to the thermoelectric module. In Around the world, the more research for into improving the efficiency of thermoelectric modules is focused on the current materials. at present. However, the research of into available materials had has some limitations, and the research of materials had reached a bottleneckthere are limits to current applications. On the other hand, from the production process, if we assembled by materials withoutmodules without any damages and achieve the ideal state of a joint, we can make the a product to maximize performance and have a longer service life. SoTherefore, in this study we will prove the relationship between the any defects inside and the efficiency of a thermoelectric module to improve the quality management and performance of modern thermoelectric modules at present.

• Journal of Mechanical Science and Technology
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• 제17권3호
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• pp.357-369
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• 2003

Electromagnetic valve (EMV) actuation system is a new technology for improving fuel efficiency and at the same time reducing omissions in internal combustion engines. It can provide more flexibility in valve event control compared with conventional variable valve actuation devices. The electromagnetic valve actuator must be designed by taking the operating conditions and engine geometry limits of the internal combustion engine into account. To help develop a simple design method, this paper presents a procedure for determine the basic design parameters and dimensions of the actuator from the relations of the valve dynamics, electromagnetic circuit and thermal loading condition based on the lumped method. To verify the accuracy of the lumped method analysis, experimental study is also carried out on a prototype actuator. It is found that there is a relatively good agreement between the experimental data and the results of the proposed design procedure. Through the whole speed range, the actuator maintains proper performances in valve timing and event control.