• 품질경영학회지
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• 제24권1호
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• pp.1-9
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• 1996

Ritchken(1985) analyzes free replacement and pro-rata warranty policies for products receiving renewable warranies. He shows that for constant failure rates pro-rata warranty policies are more attractive to risk-averse manufacturers than shorter term free replacement policies that result in the same average warranty cost. This paper considers the case when product lifetimes distributions are of phase-type. When this is so, Ritchken's performance measures can be simplified considerably. It is found, that irrespective of the pattern of failure rates, pro-rata warranty policies are preferable to free replacement policies. But the warranty period of the equivalent free replacement policy decreases and then increases, as product reliability(the average time between failures) increases.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2961-2966
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• 2010

Reduction of carbonyl compounds such as aldehydes, ketones, $\alpha,\beta$-unsaturated enals and enones, $\alpha$-diketones and acyloins was carried out readily with $NaBH_3CN$ in the presence of wet $SiO_2$ as a neutral media. The reactions were performed at solvent-free conditions in oil bath (70 - $80^{\circ}C$) or under microwave irradiation (240 W) to give the product alcohols in high to excellent yields. Regioselective 1,2-reduction of conjugated carbonyl compounds took place in a perfect selectivity without any side product formation.

• Korean Journal of Mathematics
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• 제14권2호
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• pp.217-226
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• 2006

In this paper, we investigate the mutual relation among short exact sequences of amalgamated free products which involve augmentation ideals and relation modules. In particular, we find out commutative diagrams having a steady structure in the sense that all of their three columns and rows are short exact sequences.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제19권4호
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• pp.349-361
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• 2012

CAT(0) cubical complexes are a key to formulate geodesic spaces with nonpositive curvatures. The paper discusses the median structure of CAT90) cubical complexes. Especially, the underlying graph of a CAT(0) cubical complex is a median graph. Using the idea of median structure, this paper shows that groups acting on median complexes L(${\delta}$) groups and, in addition, work L(0) groups are closed under free product.

• 한국산학기술학회논문지
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• 제21권2호
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• pp.103-114
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• 2020

입국장 면세점은 내국인 여객들이 출국장 면세점에서 구매한 물품을 여행 기간 내내 휴대해야 했던 불편함이 해소해 준다. 공항 입국장 면세점 설치는 많은 내국인 여객들이 오래 전부터 요구해 온 사안으로 최근 해외여행이 보편화되고 동북아 주변국 공항들이 허브공항 경쟁을 강화하면서 이번 정부의 결정은 매우 시의 적절했다는 평가를 받고 있다. 본 연구는 출국장 면세점 및 입국장 면세점의 일별 매출 자료를 토대로 판매품목 별 매출 액 간 관계성을 분석하고자 하였다. 이러한 관계성 분석을 토대로 인천국제공항 입국장 면세점 개장이 기존 출국장 면세점 매출에 긍정적 또는 부정적 영향을 미쳤는지 실증적으로 분석하고 이를 토대로 정책적 시사점을 제시하고자 하였다. 중소기업이 입국장 면세점 사업자로 선정되고 판매품목이 제한되어 가격경쟁력과 상품구성 및 기획력 등에서 대기업 위주의 출국장 면세점 사업자와 대등한 경쟁이 될 수 없는 취약점을 내포하고 있다. 향후 현재와 동일한 여건이라면 출국장 면세점에서 고관여 제품(패션악세사리, 가죽피혁 등)을 구매한 출국여객과 이외의 상품을 구매한 경우 출입국시 상호 보완적인 구매행태를 보이고, 매출에 있어 자기잠식이 발생하지 않고 있어 사업초기에 전개하는 상품기획과 마케팅 활동을 더욱 활성화할 때 매출증대와 인지도를 강화할 수 있겠다는 시사점을 도출하였다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 ISMP Pb-free solders and the PCB technologies related to Pb-free solders
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• pp.93-99
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• 2004

At present, LG Electronics pushes ahead to eliminate the Pb(Lead) -a hazardous material- from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C-+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.

• 한국유기농업학회지
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• 제26권3호
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• pp.351-367
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• 2018

This study aimed to analyze socioeconomic effect of eco-friendly free school food supply system by Seoul, which has been consistently extended since 2011. To do so, effect of eco-friendly free school food supply system on the beneficiaries, Seoul citizens, was analyzed by using 'labor & income panel', while that on rural society was analyzed by using the surveys on the eco-friendly agricultural product supply performance by the 'Eco-friendly Agricultural Products Retail Center' as well as for students, school parents, nutrition teachers and nutritionists. The results of analysis showed that eco-friendly school food supply system contributes to income redistribution among the Seoul citizens to a certain extent, provides the eco-friendly agricultural product producers in the rural society with the stable market, and positively influences them to secure stable incomes. In addition, eco-friendly free school food reduced the amount of carbon emissions through the use of environmentally friendly agricultural products resulting in environmental improvements and economic benefits. Considering such effects, free school food supply using the eco-friendly agricultural products needs to be consistently maintained in the future without politic change by political ideology and to be extended to middle school level in medium and short-term.

• Parasites, Hosts and Diseases
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• 제54권5호
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• pp.679-684
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• 2016

Clonorchiasis, caused by direct contact with Clonorchis sinensis worms and their excretory-secretory products (ESPs), is associated with chronic inflammation, malignant changes in bile ducts, and even cholangiocarcinogenesis. Our previous report revealed that intracellular free radicals enzymatically generated by C. sinensis ESPs cause NF-${\kappa}B$-mediated inflammation in human cholangiocarcinoma cells (HuCCT1). Therefore, the present study was conducted to examine the role of upstream Toll-like receptors (TLRs) on the initial host innate immune responses to infection. We found that treatment of HuCCT1 cells with native ESPs induced changes in TLR mRNA levels in a time-dependent manner, concomitant with the generation of free radicals. ESP-mediated free radical generation was markedly attenuated by preincubation of the cells with TLR1-4-neutralizing antibodies, indicating that at least TLR1 through 4 participate in stimulation of the host innate immune responses. These findings indicate that free radicals triggered by ESPs are critically involved in TLR signal transduction. Continuous signaling by this pathway may function in initiating C. sinensis infection-associated inflammation cascades, a detrimental event leading to progression to more severe hepatobiliary diseases.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 ISMP Pb-free solders and the PCB technologies related to Pb-free solders
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• pp.79-92
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• 2004

RoHS compliant products are now being mass-produced. Eco-product(Pb-free+RoHS compliant+Halogen-free) will be possible from 2005. Pb-free flip chip will be qualified by 2004. 4Q. Lead Finish: SnBi-Under mass production Pd PPF-Under small production Matte Sn-will be internally qualified by 2004. 4Q Development of Pb-free Solder Ball: Stable Supply, Cost Down.

• 호남수학학술지
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• 제28권4호
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• pp.499-511
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• 2006

It is well-known that every finitely generated torsion-free module over a principal ideal domain is free. This will be generalized. We deal with ideals of the finite, external direct product of certain rings. Finally, if M is a torsion-free, finitely generated module over a reduced, Noetherian ring A, then we prove that Ms is a projective module over As, where $S=A{\setminus}(A)$.