• International Journal of Advanced Culture Technology
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• 제8권4호
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• pp.110-118
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• 2020

It is important to have an appropriate amount of inventory for effective operations. This study seeks to develop a sustainable newsvendor model by incorporating environment-related costs into the existing well-known (single-period) newsvendor model. Since leftovers do more harm to environments than stockouts, the optimal order amount tends to be lower than the traditional quantity. However, this is not the case when a second buy is allowed. A second order opportunity is prevalent in industries where it improves demand forecast despite incurring extra costs. In this study, we conduct an extensive numerical analysis for a newsvendor situation with a permitted second buy. The results show that we can reduce inventory costs by considering sustainability concerns. The research idea of including sustainability considerations into existing inventory models can be extended to a more general case and provides managerial insights for better inventory decisions.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 제3회 압연심포지엄 논문집 압연기술의 미래개척 (Exploitation of Future Rolling Technologies)
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• pp.293-300
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• 1999

A mathematical model for the analysis of roll gap phenomena in strip temper rolling process is described. The mechanical peculiarities of temper rolling process, such as high friction value and non-circular contact arc, low reduction and non-negligible entry and exit elastic zones as well as central restricted deformation (preliminary displacement or sticking) zone etc., are all taken into account. The deformation of work rolls is calculated with the influence function method and arbitrary contact arc shape is permitted. The strip deformation is modeled by slab method and the entry and exit elastic deformation zones are included. The restricted deformation zone near the neutral point is also considered. The concept and the calculation method of limiting preliminary displacement are used to determine the length of the central restricted deformation zone. The comparison of the model results with the measured mill data is also made.

• 한국환경교육학회지:환경교육
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• 제17권1호
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• pp.12-24
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• 2004

The purpose of this study was to analyze and compare Korean middle school-level environmental education(EE) textbooks. More specifically, these analyses and comparisons were designed to explore the extent to which environmental investigation skills were addressed in these EE textbooks (i.e., curriculum inclusion), as well as the manner in which these skills were to be taught and learned (i.e., instructional approaches). To analyze EE textbooks, the researchers developed a 'Curriculum Analysis Chart' that include six skill clusters and four instructional strategies. This analytic chart permitted the researchers to determine which skills were featured in selected textbooks, as well as which skill-oriented instructional strategies accompanied each of those skills. The chart was revised several times through pilot analyses. Using the final version of this chart, the researchers analyzed and then compared the three textbooks. This analysis indicated that the Korean middle school-level EE textbooks were designed to support conceptual learning and understanding of environment and environmental problems/issues (i.e., content-oriented), and were designed to support skill learning to a moderate degree. On the basis of textbooks analysis, the researchers offered several recommendations for future research, and for educational practices in EE.

• Weed & Turfgrass Science
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• 제3권3호
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• pp.221-224
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• 2014

Genetically modified (GM) crops are not permitted to be cultivated in Korea, but can only be imported as food or feed purposes. The import of GM crops has sharply increased in recent years, thus raising concerns with regard to the unintentional escape of these crops during transport and manufacturing as well as the subsequent contamination of local, non-GM plants. Hence, monitoring of GM crops was studied in or outside of grain receiving ports as well as from feed-processing plants in Korea during July 2008. We observed spilled maize grains and established plants primarily in storage facilities that are exposed around the harbors and near transportation routes of the feed-processing areas. Based on the PCR analyses, a total of 17 GM maize plants and 11 seeds were found among the samples. In most cases, the established maize plants found in this study were at the vegetative stage and thus failed to reach the reproductive stage. This study concludes that, in order to prevent a genetic admixture in the local environment for GM crops or seeds, frequent monitoring work and proper action should be taken.

• 헤리티지:역사와 과학
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• 제36권
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• pp.313-334
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• 2003

Historically, hawking/falconry refer to the hunting for pheasants, birds and hares using a hawk. In spite of its long history, not so many studies were found and/or have been performed. Examining researches, hawking has been enjoyed solely by the royal families until the early Joseon Dynasty but it has been popularly spread among the people in the 18th century, emphasizing recreational factors of it. The researches, however, dealt only with the limited data published by the government while a diary, Swaemirok written by Oh Hi-Mun, an intellectual in the 16th century noted the realities and characteristics of hawking at that time. According to the diary, hawking has been spread all over the country in the 16th century and the people as well as the royal families enjoyed it. The hawking season has been continued for a year except for summertime trees and plants grow thick. For the hawking, they need to be permitted officially or under a tacit consent. In those days, beef and pork are very rare. A peasant acted as, therefore, an excellent alternative and was served up for a religious service. In view of the truth, it could be stated that peasant-hawking was important for recreational activities as well as for their living.

• Journal of Power Electronics
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• 제17권2호
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• pp.334-345
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• 2017

In order to meet the increasing needs of the hybrid energy source system for electric vehicles, which demand bidirectional power flow capability with a wide-voltage-conversion range, a bidirectional three-level DC-DC converter and some control strategies for hybrid energy source electric vehicles are proposed. The proposed topology is synthesized from Buck and Boost three-level DC-DC topologies with a high voltage-gain and non-extreme duty cycles, and the bidirectional operation principle is analyzed. In addition, the inductor current ripple can be effectively reduced within the permitted duty cycle range by the coordinated control between the current fluctuation reduction and the non-extreme duty cycles. Furthermore, benefitting from duty cycle disturbance control, series-connected capacitor voltages can also be well balanced, even with the discrepant rise and fall time of power switches and the somewhat unequal capacitances of series-connected capacitors. Finally, experiment results of the bidirectional operations are given to verify the validity and feasibility of the proposed converter and control strategies. It is shown to be suitable for hybrid energy source electric vehicles.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.486-493
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• 2017

Refineries and chemical plants with isolated power systems that have a limited power supply are more susceptible to voltage changes from disturbances compared to power systems connected with a power company. Furthermore, most loads in such cases are induction motor loads, and therefore, transient voltage characteristics when starting a high-capacity motor must be examined. In general, high-capacity motors are customized appropriately to the load performance curve by the manufacturer during the construction of an industrial plant. Subsequently, when complying with the voltage drop permitted by international standards during the design process, power supply equipment such as transformers and generators is overdesigned. Therefore, a novel analysis is necessary on standards for startup and constraint voltage drops, as well as on identifying the voltage drop limitations for starting high-capacity motors in refineries and chemical plants with isolated power systems. In this study, field tests on an industrial plant were conducted, and simulations modeled under conditions identical to those of the field test system were performed using the general-purpose program ETAP in order to compare the results.

• 항공우주정책ㆍ법학회지
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• 제12권
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• pp.36-65
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• 2000

The Montreal Convention markedly changed the rules governing the international carriage by air of passenger, baggage and cargo. The introduction of a considerable number of modernized major elements including electric ticketing system, the unlimited passenger liability regime and a supplementary (fifth) jurisdiction should help to remove aged scheme that now exists in the Warsaw Convention and other related instruments. The key issue of the electric ticketing system recognized by the Convention IS how to describe reasonably and adequately the terms of written notices, in the light of the principle of consumer protection. Regarding liability regime for passengers, an unlimited passenger liability regime is realized. The carrier, in the first tier, is subject to a strict liability regime of up to 100,000 SDRs, and in the second tire, a regime of presumed fault liability without numerical liability limits. To add to the present four fora, the fifth forum is permitted. Regarding damage resulting the death or injury of a passenger, an action for damages may also be brought in its home territory with the considerably qualified narrow requirements. A strange deviation from the well-established "Procedure for Approval of Draft Convention" carried out by the Legal Committee left a considerable number of unrefined and incomplete passages. In the near future, their modification should be required.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.257-260
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• 2002

이 연구는 지하수개발사업 타당성 분석을 지원하기 위한 Desk GIS에 기반한 지하수사업기초조사지원 시스템을 개발하는 것이 목적이다. 개발된 시스템을 이용하면, 신규 개발 예정관정에 대하여 GIS안에서 모의 양수실험을 할 수 있으며, 기설관정의 채수영향반 경과의 중첩여부, 오염원 등과 비교하여 지하수관정개발사업의 허가여부를 판단할 수 있다. 농업기반공사 등 지하수 관련 부서들이 전사적으로 지하수 관련자료를 공유할 수 있으며, 자료의 정확성, 신뢰성 그리고 최신정보를 공유할 수 있을 것이다.

• Radiation Oncology Journal
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• 제32권3호
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• pp.103-115
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• 2014

To summarize current knowledge regarding mechanisms of radiation-induced normal tissue injury and medical countermeasures available to reduce its severity. Advances in radiation delivery using megavoltage and intensity-modulated radiation therapy have permitted delivery of higher doses of radiation to well-defined tumor target tissues. Injury to critical normal tissues and organs, however, poses substantial risks in the curative treatment of cancers, especially when radiation is administered in combination with chemotherapy. The principal pathogenesis is initiated by depletion of tissue stem cells and progenitor cells and damage to vascular endothelial microvessels. Emerging concepts of radiation-induced normal tissue toxicity suggest that the recovery and repopulation of stromal stem cells remain chronically impaired by long-lived free radicals, reactive oxygen species, and pro-inflammatory cytokines/chemokines resulting in progressive damage after radiation exposure. Better understanding the mechanisms mediating interactions among excessive generation of reactive oxygen species, production of pro-inflammatory cytokines and activated macrophages, and role of bone marrow-derived progenitor and stem cells may provide novel insight on the pathogenesis of radiation-induced injury of tissues. Further understanding the molecular signaling pathways of cytokines and chemokines would reveal novel targets for protecting or mitigating radiation injury of tissues and organs.