• 한국산학기술학회논문지
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• 제17권8호
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• pp.691-697
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• 2016

재제조란 고객시장으로부터 회수된 중고품의 닳거나 고장 난 부품을 성한 것으로 교체하여 재제조품 시장에 재판매하는 것을 말한다. 본 논문은 사용된 제품의 회수량이 회수 가격의 함수로 나타나며 일정 계획기간 동안의 재제조품에 대한 수요량이 주어진 경우의 회수 및 재제조 정책을 다룬다. 회수한 사용후 제품은 분해 검사를 통하여 품질을 확인하며 검사가 끝난 회수제품의 품질이 고품질과 저품질의 두 부류로 분류되고 품질 수준에 따라 재제조비용이 상이해 지는 현실적 상황을 가정한다. 두 부류의 분류확률에 불확실성이 없는 경우 및 불확실성이 있는 경우 각각을 대상으로 재제조 시스템의 총비용을 최소화 하는 회수가격 및 재제조 정책을 결정하기 위한 수리모형을 개발한다. 개발한 모형의 수리적 특성을 분석하여 최적해를 구하는 절차를 찾아내고, 최적해가 얻어지는 경우를 분석하여 재제조시스템의 생산경영자에게 시사해주는 검사비용 크기의 경영학적 함의를 밝힌다. 수치 예를 통하여 검사비용 및 회수품 시장규모가 변화함에 따라 최적회수가격이 변화하는 양태를 분석하여 최적해의 민감도를 분석하고, 고품질과 저품질의 어느 한 부류로 분류되는 확률의 불확실성이 커질 때 불확실성을 무시한 의사결정의 오류가 어떻게 변화하는지 고찰한다.

• 한국콘텐츠학회논문지
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• 제15권12호
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• pp.73-80
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• 2015

1996년 중국으로 수출된 한국 드라마의 인기를 시작으로 세계 시장에서는 이른바 한류 열풍이 시작되었다. 이후 드라마뿐만 아니라 한국의 문화 자체가 한류 시장의 콘텐츠로 급부상하며 한국 제품을 온라인에서 직접 구매하고자 하는 해외 직판 소비자가 큰 폭으로 증가하고 있다. 본 연구는 국내 온라인 쇼핑몰이 해외 시장의 소비자 환경에 적절히 부응하고 있는가를 파악하기 위해 현재 글로벌 마케팅을 진행하고 있는 국내 쇼핑몰 네 곳과 해외의 유명 쇼핑몰 네 곳을 각각 선정하여 디자인 측면을 비교 연구하였다. 그 결과 글로벌 마케팅을 진행하고 있는 국내 온라인 쇼핑몰들이 국가별 인터넷 환경에 대한 이해가 부족하고 문자 정보전달의 한계를 겪고 있으며 의미 전달에 용이한 시각 기호를 적극적으로 활용하지 못하고 있는 실정임이 드러났다. 이에 본 논문은 그러한 문제점에 대한 개선 방안으로 다양한 화면을 배려하는 가변 요소를 디자인에 활용하는 방안, 세계 각국마다 다른 언어의 문제를 해결하기 위해 텍스트를 직관적인 요소로 디자인하는 방안, 발전하는 IT기술을 적극 활용하여 디자인하는 방안 등을 제시하였다.

• 디지털융복합연구
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• 제14권9호
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• pp.89-97
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• 2016

소득증대와 고용창출의 핵심역할을 하는 지식재산권은 특히 창조경제에서 매우 중요한 역할을 한다. 많은 기업들은 이러한 패러다임에서 브랜드관리에 심혈을 기울이고 있는 가운데 강력한 브랜드자산을 구축함으로써 궁극적으로 이윤극대화 등 기업의 경영성과를 올리기 위한 노력이 높아지고 있다. 기술거래 및 사업화, 금융지원, 투자의 사결정, M&A, 소송, 브랜드전략 등의 목적에서 브랜드 재활성화(revitalizing)를 위한 상표권 가치의 합리적 평가는 매우 중요한 것이라 할 것이다. 그러나 이러한 중요함에도 불구하고 지식재산권에 대한 인식부족과 평가하는 역량은 매우 부족한 실정이다. 이에 본 연구는 기업상표권 가치평가를 위해 실제 상표권을 보유하고 있는 사례기업을 대상으로 원가법과 수익접근법에 의한 사례분석을 실시하여, 원가법의 205백만원에서부터 수익접근법의 변동할인율, 조정기여도를 적용한 270백만원까지 다양한 결과를 제시하였다. 하지만 단일기업을 통해 시사점을 얻은 것은 본 연구의 한계이며, 향후 규모별, 업종별 다양한 기업군의 사례분석과 적용반안에 대한 연구가 계속되어야 할 것이다.

• 산업경영시스템학회지
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• 제40권4호
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• pp.253-259
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• 2017

Recent development in science and technology has modernized the weapon system of ROKN (Republic Of Korea Navy). Although the cost of purchasing, operating and maintaining the cutting-edge weapon systems has been increased significantly, the national defense expenditure is under a tight budget constraint. In order to maintain the availability of ships with low cost, we need accurate demand forecasts for spare parts. We attempted to find consumption pattern using data mining techniques. First we gathered a large amount of component consumption data through the DELIIS (Defense Logistics Intergrated Information System). Through data collection, we obtained 42 variables such as annual consumption quantity, ASL selection quantity, order-relase ratio. The objective variable is the quantity of spare parts purchased in f-year and MSE (Mean squared error) is used as the predictive power measure. To construct an optimal demand forecasting model, regression tree model, randomforest model, neural network model, and linear regression model were used as data mining techniques. The open software R was used for model construction. The results show that randomforest model is the best value of MSE. The important variables utilized in all models are consumption quantity, ASL selection quantity and order-release rate. The data related to the demand forecast of spare parts in the DELIIS was collected and the demand for the spare parts was estimated by using the data mining technique. Our approach shows improved performance in demand forecasting with higher accuracy then previous work. Also data mining can be used to identify variables that are related to demand forecasting.

• 설비공학논문집
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• 제18권11호
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• pp.915-922
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• 2006

Considering heat pipe design principles in fabrication and operational performances, water is one of the most recommended working fluids to make mid to low tempera lure heat pipes. But the conventional water heat pipes might encounter the failure in a cold start-up operation when socked at a chilling temperature lower than the freezing point. If they are subjected to a heat supply for start-up at a temperature around $-20^{\circ}C$, the rate of the vapor flow and the corresponding heat transfer from the evaporator to the condenser is so small that the vapor keeps to stick on the surface of the chilling condenser wall, forming an ice layer, resulting in a liquid deficiency in the evaporator. This kind of problems was resolved by Kang et al. in 2004 by adopting a gas loading heat pipe technology to the conventional water heat pipes. This study was conducted to examine a chilling start-up procedure of gas loading heat pipes by investigating the behaviors of heat pipe wall temperatures. And the thermal resistance of the gas loaded heat pipe that depends on the operating temperatures and heat loads was measured and examined. Two water heat pipes were designed and fabricated for the comparison of performances, one conventional and the other loaded with $N_2$ gas. They were put on start-up test at a heat supply of 30 W after having been socked at an initial temperature around $-20^{\circ}C$. It was observed that the gas loaded one had succeeded in chilling start-up operation.

• 소성∙가공
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• 제30권6호
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• pp.291-300
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• 2021

Currently, starting with electric vehicles, the application of ultra-high-strength steel sheets and light metals has expanded to improve mileage by reducing vehicle weight. At a time when internal combustion engine vehicles are rapidly changing to electric vehicles, the application of ultra-high-strength steel is expanding to satisfy both weight reductions and the performance safety of the chassis parts. There is an urgent need to improve the quality of parts without defects. It is particularly difficult to estimate the part formability through the finite element method (FEM) in the burring operation, so product design has been based on the hole expansion ratio (HER) and experience. In this study, design of experiment (DOE), analysis of variance (ANOVA), and regression analysis were combined to optimize the formability by adjusting the process variables affecting the burring formability of ultra-high-strength steel parts. The optimal variables were derived by analyzing the influence of variables and the correlation between the variables through FE analysis. Finally, the optimized process parameters were verified by comparing experiment with simulation. As for the main influence of each process variable, the initial hole diameter of the piercing process and the shape height of the preforming process had the greatest effects on burring formability, while the effect of a lower round of punching in the burring process was the least. Moreover, as the diameter of the initial hole increased, the thickness reduction rate in the burring part decreased, and the final burring height increased as the shape height during preforming increased.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.959-964
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• 2022

Lead is an important material, both for fusion or fission reactors. The cross sections of natural lead should be validated because lead is a main component of lithium-lead modules suggested for fusion power plants and it directly affects the crucial variable, tritium breeding ratio. The presented study discusses a validation of the lead transport libraries by dint of the activation of carefully selected activation samples. The high emission standard ²⁵²Cf neutron source was used as a neutron source for the presented validation experiment. In the irradiation setup, the samples were placed behind 5 and 10 cm of the lead material. Samples were measured using a gamma spectrometry to infer the reaction rate and compared with MCNP6 calculations using ENDF/B-VIII.0 lead cross sections. The experiment used validated IRDFF-II dosimetric reactions to validate lead cross sections, namely ¹⁹⁷Au(n, 2n)¹⁹⁶Au, ⁵⁸Ni(n,p)⁵⁸Co, ⁹³Nb(n, 2n)^92mNb, ¹¹⁵In(n,n')^115mIn, ¹¹⁵In(n,γ)^116mIn, ¹⁹⁷Au(n,γ)¹⁹⁸Au and ⁶³Cu(n,γ)⁶⁴Cu reactions. The threshold reactions agree reasonably with calculations; however, the experimental data suggests a higher thermal neutron flux behind lead bricks. The paper also suggests ²⁵²Cf isotropic source as a valuable tool for validation of some cross-sections important for fusion applications, i.e. reactions on structural materials, e.g. Cu, Pb, etc.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4195-4208
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• 2022

In this study, operator habitability was numerically evaluated in the event of a fire at the main control bench board (MCB) in a reference main control room (MCR). It was investigated if evacuation variables including hot gas layer temperature (HGLT), heat flux (HF), and optical density (OD) at 1.8 m from the MCR floor exceed the reference evacuation criteria provided in NUREG/CR-6850. For a fire model validation, the simulation results of the reference MCR were compared with existing experimental results on the same reference MCR. In the simulation, various input parameters were applied to the MCB panel fire scenario: MCR height, peak heat release rate (HRR) of a panel, number of panels where fire propagation occurs, fire propagation time, door open/close conditions, and mechanical ventilation operation. A specialized-average HRR (SAHRR) concept was newly devised to comprehensively investigate how the various input parameters affect the operator's habitability. Peak values of the evacuation variables normalized by evacuation criteria of NUREG/CR-6850 were well-correlated as the power function of the SAHRR for the various input parameters. In addition, the evacuation time map was newly utilized to investigate how the evacuation time for different SAHRR was affected by changing the various input parameters. In the previous studies, it was found that the OD is the most dominant variable to determine the MCR evacuation time. In this study, however, the evacuation time map showed that the HF is the most dominant factor at the condition of without-mechanical ventilation for the MCR with a partially-open false ceiling, but the OD is the most dominant factor for all the other conditions. Therefore, the method using the SAHRR and the evacuation time map was very useful to effectively and comprehensively evaluate the operator habitability for the various input parameters in the event of MCB fires for the reference MCR.

• 여성건강간호학회지
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• 제28권1호
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• pp.46-55
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• 2022

Purpose: This study aimed to determine the level of postpartum posttraumatic stress disorder (PTSD) and postpartum depression (PPD) in Korean mothers with healthy babies and to explore the factors related to postpartum PTSD. Methods: This study used a longitudinal survey design to explore the levels and association of PPD and PTSD. Two hundred women were recruited during pregnancy and the data were collected via online survey from 166 mothers (84% retained) who gave birth to healthy babies, at two postpartum periods: Fear of childbirth was assessed at the 1st week; and spousal support, PPD, and postpartum PTSD were surveyed at the 4th week postpartum. Descriptive statistics, t-test, one-way analysis of variance, Chi square test, and multiple regression were done. Results: The mean age of mothers was 33.12 (±3.97) years old. Postpartum PTSD was low (8.95±6.49) with 1.8% (n=3) at risk (≥19). PPD was also low (6.68±5.28) and 30.1% (n=50) were identified at risk (≥10). The comorbid rate of PPD with PTSD was 6%. Mothers who did not have a planned pregnancy had higher scores of PPD (t=-2.78, p=.008), whereas spousal support and PPD had negative relationship (r=-.21, p=.006). The overall explanatory power for postpartum PTSD was 55.2%, of which PPD was the only significant variable (β=. 76, t=13.76, p<.001). Conclusion: While only 1.8% was at risk of postpartum PTSD at 4 weeks postpartum, PPD prevalence was 30.1% and PPD was the only influential factor of postpartum PTSD. Assessment and counseling of PPD are required as well as screening for postpartum PTSD. More research is also needed on postpartum PTSD in Korean women.

• 청정기술
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• 제13권1호
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• pp.34-45
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• 2007

고지혈증 치료제로 잘 알려져 있는 난용성 약물인 심바스타틴(simvastatin)을 대상으로 디클로로메탄을 용매로 사용하고 초임계 이산화탄소를 역용매로 사용하는 초임계 역용매 재결정법에 의해 약물 미세입자를 제조할 때, 운전 조건을 설정하는데 활용될 수 있는 가이드 라인을 제공하기 위하여 simvastatin/디클로로메탄/초임계 이산화탄소 3성분계 혼합물의 상거동을 연구하였다. 가변부피 투시 셀이 장착된 고압 상평형 장치를 사용하여 여러 가지 조건에서 3성분계 혼합물의 구름점(cloud point)을 측정함으로서 디클로로메탄과 초임계 이산화탄소의 혼합용매에서 simvastatin의 용해도를 온도, 압력, 용매 조성의 함수로 결정하였다. 주어진 온도에서 Simvastatin 약물의 용해도는 디클로로메탄의 조성과 압력이 증가할수록 온도가 감소할수록 증가하였다. 상거동 데이터를 바탕으로 교반기가 설치된 실린더 모양의 고압 용기에서 초임계 역용매 재결정 공정을 이용하여 simvastatin 약물을 미세입자로 제조하는 연구를 수행하였다. 운전 조건인 압력 ($8{\sim}12\;MPa$), 온도(303.15 K, 313.15 K), 이산화탄소 공급 속도, 교반 속도 (최대 3,000 rpm)를 변화시키면서 simvastatin 미세입자를 제조함으로써 재결정되는 약물 입자의 크기와 모양에 미치는 공정 변수들의 영향을 관찰하였다.