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        검색결과 2,116

        381.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        점차 강화되는 배출가스 규제와 적은 연료로 많은 거리를 주행할 수 있는 고효율 자동차에 대한 요구로 에너지소비효율에 대한 관심이 점차 늘어나고 있다. 국내의 에너지소비효율은 도심주행모드와 고속도로 모드를 주행하여 복합연비로 산정하고 5-Cycle 보정식을 이용하여 최종 에너지소비효율을 표시하고 있다. 에너지소비효율의 경우 카본발란스법에 의하여 산출되는데 이때 배출가스에 의해 계산이 됨에 따라 연소에 사용되는 연료는 자동차 성능과 에너지소비효율에 매우 중요한 역할을 하게 된다. 자동차 연료의 경우 국내에서는 석유 및 석유대체연료 사업법 품질기준에 따라 국내에 유통되고 있는데 정유사의 정제 방법이나 원유에 따라 품질 기준 내에서 물성 차이를 보일 수 있다. 일정 품질기준을 정하고 있음에 따라 연료별 큰 차이는 나지 않을 것으로 보이나 자동차의 성능에는 영향을 미칠 수 있어 그에 따른 연구가 필요한 실정이다. 따라서, 본 연구에서는 시중에서 유통되고 있는 연료 중 여름철에 판매되는 경유를 정유사 직영점을 통해 구매하였으며, 각 시료별 물성을 분석하고 그에 따른 에너지소비효율을 측정하였다. 에너지소비효율의 경우 현행 경유 자동차의 에너지소비효율 산정식과 휘발유 에너지소비효율에서 사용되는 산출식을 이용하여 물성 적용에 따른 변화를 살펴보았다. 그 결과 시료별 밀도는 최대 약 0.9%의 차이를 보였으며, 순발열량은 1.6%의 차이를 보였으며, 현행 에너지소비효율 산출 결과에서는 도심모드에서 약 1%, 고속모드에서 1.4% 차이를 보였다. 휘발유 산출식을 이용한 산출에서는 현행 에너지소비효율 산출때 보다 약 6%정도 낮은 수치를 보였으며, 각 시료별 에너지소비효율은 최대 도심과 고속에서 최대 약 1.4%의 차이를 보였다.
        4,000원
        382.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 전기분해 방법을 이용한 질산성질소(NO3 --N) 분해가 TiO2 nanotube plate 및 구리, 니켈, 스테인리스 스틸, 알루미늄, 주석, 티타늄을 환원전극으로 사용하였을 때 가능한지를 평가하였다. 전극의 전기화학적 특성 평가는 임피던스 측정을 하여 비교하였고, TiO2 nanotube plate의 표면 분석은 주사전자현미경을 통해 SEM 및 BET 분석법을 이용한 비표면적 분석을 통해 비교하였다. 질산성질소 전해실험의 경우 90분의 실험을 진행하였으며, 실험 결과 전극 표면의 부식이 수반되지 않은 TiO2 nanotube plate가 기타 금속 전극에 비해 질산성질소 환원 반응속도가 가장 뛰어난 것으로 확인되었다.
        4,000원
        383.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        OLED Display fabrication system is one of the most complicated discrete processing systems in the world. As the glass size grows from 550×650mm to 1,500×1,850mm in recent years, the efficiency of Automated Material Handling System (AMHS) has become very important and OLED glass manufacturers are trying to improve the overall efficiency of AMHS. Aiming to meet the demand for high efficiency of transportation, various kind of approaches have been applied for improving dispatching rules and facility layout, while simultaneously considering the system parameters such as glass cassettes due date, waiting time, and stocker buffer status. However, these works did not suggest the operational policy and conditions of distribution systems, especially for handling unnecessary material flows such as detour. Based on this motivation, in this paper, we proposed an efficient algorithm for improving detour transportation in OLED FAB. Specifically, we considered an OLED FAB simplifying OLED production environment in a Korean company, where four stockers are constructed for the delivery of Lot in a bay and linked to processing equipments. We developed a simulation model using Automod and performed a numerical experiment using real operational data to test the performance of three operation policies under considerations. We showed that a competitive policy for assigning alternative stocker in case of detour was superior to the current dedicated policy using a specified stocker and other considered policies.
        4,000원
        384.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to analyze the efficiencies of project management offices in large information system construction projects using the data envelopment analysis. In addition, we tried to estimate the confidence interval of those efficiencies using bootstrap DEA to give a statistical meaning. The efficiency by the CCR model is analyzed as eight project management offices are fully efficient and 22 project management offices are inefficient. On the other hand, there are 15 project management offices are fully efficient, but 15 project management offices are inefficient in the BCC model. As the result of the scale efficiencies, of the inefficient project management offices, 13 project management offices are inefficient in scale. It is possible to eliminate the inefficiency in the CCR model by improving their project performances. And, the nine project management offices showed that the inefficiency was due to pure technical efficiency, and these companies should look for various improvements such as improvement of project execution system and project management process. In order that the inefficient project management offices be efficient, it is analyzed that more efforts must be made for on-budget and on-time as a result of examining the potential improvement potentials of inefficient project management offices.
        4,200원
        385.
        2018.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study is to improve effectiveness of Korea’s Official Development Assistance (ODA) provided to developing countries. To do this, we analyze the efficiency of ODA provided to 38 recipient countries by Korea through data envelope analysis method. The effects of four factors including population, GDP, economic decline and poverty, and external intervention on efficiency are also investigated by utilizing tobit regression analysis. As a result of the DEA efficiency analysis, it is found that the average efficiency score of the total is about 59%. By region, the average efficiency score of Asia, Africa, Central and South America, and the East and CIS (Commonwealth of Independent States) are about 42%, 68%, 70%, and 74%, respectively. It indicates that the Asian countries are inefficient compared to countries of the other regions. It is also found that factors of population, GDP, economic decline and poverty, and external intervention have statistically significant effects on efficiency at 0.01 significance level. In the case of the population, the higher the population of the recipient country, the more negative (-) effect is on the efficiency. The other factors such as GDP, economic decline and poverty, and external intervention have positive effects on the efficiency.
        4,000원
        386.
        2018.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, high thermal efficiency and eco-friendly coffee roaster is developed. The core element of coffee roaster is a roasting drum and most of the coffee roasting drum is a flat cylindrical barrel type. From the traditional shape of cereal puffing machine, we got the idea of the roasting drum. Oak barrel shape is well known high thermal efficiency system in korean heating cook system. Therefore, we designed the coffee roaster containing the oak barrel shaped drum and combustor nozzles which has an ability of roasting 3kg of coffee beans within 10 minutes of roasting time. With our developed coffee roasting machine, the heating speed of roasting process is very fast, and the roasting of coffee beans can be quickly finished. We experimented the roasting time and compared the results with other coffee roasting machines of the same amount of roasting capacity. The results were outstanding in roasting time and the quality of roasting. In spite of smaller fuel consumption, the roasting time was more shorter than flat cylindrical roasting drum.
        4,000원
        387.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        2010년 1월 해양사고조사코드의 발효를 통하여 해양사고 조사에 대한 표준화된 지침이 마련되었고, 더불어 국제해사기구는 체 약국에게 동 지침의 준해양사고제도의 관리를 권고함에 따라 우리나라에서도 2010년 해양사고의 조사 및 심판에 관한 법률에 준해양사고 제도에 관한 조항을 신설하게 된다. 중앙해양안전심판원은 준해양사고제도의 효율적 운영을 통하여 해양사고를 예방하고자 다각적인 노력을 기울이고 있으나 본 제도는 좀처럼 활성화되지 못하고 있다. 본 연구는 준해양사고제도의 운영실태와 문제점을 살펴보고, 해외의 우수한 준해양사고제도 및 철도, 항공 등의 유사교통기관의 준사고제도를 분석함으로써 준해양사고제도의 효율적 이행을 위한 방안을 제시 하는 데 그 목적이 있다. 이에는 특히 준해양사고 자율보고로의 전환, 사법적 기능이 없는 민간단체로의 이관, 준해양사고보고에 대한 인 센티브 제도의 확대, 법제도 개선 및 세부 이행 지침의 마련 등이 포함된다.
        4,000원
        388.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The ultimate goal of this development is a hybrid solar energy storage device. It supplies stable power to the load due to the emergency generator that compensates for the power shortage due to solar power generation. We have developed a stand-alone photovoltaic power generation and energy storage system with a dual inverter that extends the performance life of the PV system. It solves the problem of shortening the lifespan of battery due to repetition of charge / discharge of PV system and supplies stable power to load due to emergency generator that compensates for power shortage due to solar power generation, and furthermore, A stand-alone photovoltaic power generation system having a dual inverter for extending the life span and a control method thereof. We have also developed an optimized energy solution that enables us to save and use the remaining surplus power in the ESS to save energy through efficiency, optimization and substantial energy savings.
        4,000원
        389.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cu(II) can cause health problem for human being and phosphate is a key pollutant induces eutrophication in rivers and ponds. To remove of Cu(II) and phosphate from solution, chitosan as adsorbent was chosen and used as a form of hydrogel bead. Due to the chemical instability of hydrogel chitosan bead (HCB), the crosslinked HCB by glutaraldehyde (GA) was prepared (HCB-G). HCB-G maintained the spherical bead type at 1% HCl without a loss of chitosan. A variety of batch experiment tests were carried out to determine the removal efficiency (%), maximum uptake (Q, mg/g), and reaction rate. In the single presence of Cu(II) or phosphate, the removal efficiency was obtained to 17 and 16%, respectively. However, the removal efficiency of Cu(II) and phosphate was increased to 50~55% at a mixed solution. The maximum uptake (Q) for Cu(II) and phosphate was enhanced from 11.3 to74.4 mg/g and from 3.34 to 36.6 mg/g, respectively. While the reaction rate of Cu(II) and phosphate was almost finished within 24 and 6 h at single solution, it was not changed for Cu(II) but was retarded for phosphate at mixed solution.
        4,000원
        396.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study aimed to produce high-quality blastocysts and establish appropriate microinjection conditions for the introduction of target gene. First, we identified embryo development to the blastocyst stage after microinjection using the CRISPR/Cas9 system on the Cas9 protein or mRNA. As a result, we confirmed that blastocyst development in the Cas9 mRNA injected group significantly increased when compared to the Cas9 protein injected group (p<0.05). However, the blastocyst gene targeting rate increased in the Cas9 protein injected group when compared to the Cas9 mRNA injected group (p<0.05). Next, we treated the injection medium with 10 μg/ml of cytochalasin B (CB), and the microinjected embryos were cultured in CR1-aa medium supplemented with 0.1 μM of melatonin (Mela). Consequently, the blastocyst formation rate significantly increased in the CB treated group (p<0.05). After microinjecting embryos with the CB treated injection medium, we investigated blastocyst formation and quality via Mela treatment. Consequently, the Mela treated group demonstrated significantly increased blastocyst formation rates when compared to the non-treated group (p<0.05). Furthermore, immunofluorescence assay using RAD51 (DNA repair detection protein) and H2AX139ph (DNA damage detection protein) showed an increase in RAD51 positive cells in Mela treated embryos. Therefore, we verified the improvement in knock-in efficiency in microinjected bovine embryos using Cas9 protein. These results also demonstrated that the positive effect of the CB and Mela treatments improved the embryonic developmental competence and blastocyst qualities in genetically-edited bovine embryos.
        4,200원
        397.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In recent years, imbalanced data is one of the most important and frequent issue for quality control in industrial field. As an example, defect rate has been drastically reduced thanks to highly developed technology and quality management, so that only few defective data can be obtained from production process. Therefore, quality classification should be performed under the condition that one class (defective dataset) is even smaller than the other class (good dataset). However, traditional multi-class classification methods are not appropriate to deal with such an imbalanced dataset, since they classify data from the difference between one class and the others that can hardly be found in imbalanced datasets. Thus, one-class classification that thoroughly learns patterns of target class is more suitable for imbalanced dataset since it only focuses on data in a target class. So far, several one-class classification methods such as one-class support vector machine, neural network and decision tree there have been suggested. One-class support vector machine and neural network can guarantee good classification rate, and decision tree can provide a set of rules that can be clearly interpreted. However, the classifiers obtained from the former two methods consist of complex mathematical functions and cannot be easily understood by users. In case of decision tree, the criterion for rule generation is ambiguous. Therefore, as an alternative, a new one-class classifier using hyper-rectangles was proposed, which performs precise classification compared to other methods and generates rules clearly understood by users as well. In this paper, we suggest an approach for improving the limitations of those previous one-class classification algorithms. Specifically, the suggested approach produces more improved one-class classifier using hyper-rectangles generated by using Gaussian function. The performance of the suggested algorithm is verified by a numerical experiment, which uses several datasets in UCI machine learning repository.
        4,000원
        399.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, TMD(Tuned Mass Damper) is installed in a retractable-roof spatial structure in order to investigate dynamic response characteristics according to mass ratio and installed position of TMD on large spatial structures. The example analytical model is generated based on the Singapore sports hub stadium. Twenty eight analytical models are used to investigate optimal installation position of TMD for the example retractable-roof spatial structure using 4 to 16 TMDs. The mass of one TMD is set up 1% of total mass at the example analytical model. Displacement response ratio of model with TMD is compared with that of base model without TMD. It has been found from numerical simulation that it is more effective to install TMD at the edge of the spatial structure rather than to concentrate the TMD at the center of the spatial structure.
        4,000원