• Resources Recycling
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• v.20 no.2
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• pp.45-53
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• 2011

We devised a procedure for the recovery of silicon and tempered glass from waste photovoltaic (PV) modules using optimized conditions. The tempered glass was recovered without any damage using organic solvents. The surface material is removed by applying an acid solution on the surface of the PV cell. Through our proposed method, we offer a much more efficient approach for recycling solar cells with a surfactant than the conventional method. This process, we obtained pure silicon with a yield of 90% by chemical treatment with the surfactant at room temperature for 18 min. The silicon yield was characterized using an inductively coupled plasma-atomic emission spectrometer.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.138-151
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• 2018

In this study, development information and technologies for reusable launch vehicles were surveyed. We investigated the reusable launch vehicles developed in various countries and analyzed their recovery technologies. In particular, we focus on the technologies of the Falcon 9 of SpaceX and the New Shepard of Blue Origin, which have succeeded in several flight experiments. Moreover, we explain the control algorithms for each flight condition. Finally, we discuss the reusable technologies that can be applied to the Korean Space Launch Vehicle to reduce the launch cost.

• Journal of Korean Society of Transportation
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• v.25 no.1 s.94
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• pp.37-47
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• 2007

The Integrated Public Transport Reforms of the Seoul Metropolitan Government, which were implemented on the $1^{st}$ of July. 2004, launched a new fare allocation method. However, when a Private transit operator or a new transport system is introduced into the existing system, it will cause an allocation problem. Therefore, this study aims to Propose a rational fare allocation method which can be applicable regardless of the number of Public transportation modes or operators. To create alternatives, this study has adopted a fundamental principle of revenue allocation methods for the transit or communications sectors, and has applied it to the current transit system of Seoul. This study kas analyzed results of the cost recovery ratios and characteristics of each alternative through case studies. This study kas Presented an assessment criterion Z in order to select an optimal alternative. The criterion consists of the sum of the cost recovery ratio of each operator and the difference of the cost recovery ratio for each agency in inter-agency transit. Using the assessment criterion. the results showed that Alternative 1 is superior to the others : Alternative 1 is considering passenger-km of each operator and unit cost of passenger-km for each operator.

• The Korean Journal of Air & Space Law and Policy
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• v.17
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• pp.29-54
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• 2003

The objectives of this study are to develop more practical and efficient model concerned with airport charge, especially with aircraft landing charge. This study utilizes average pricing and marginal pricing theory as well as cost accounting theory. The average pricing method is useful to make total costs recovery possible in uncongested situation where the marginal costs are too low to recover the total costs of service. The utilization of cost accounting theory with marginal cost pricing theory would improve the practical applicability of the model. In addition, it is necessary to apply cost accounting information in order to estimate more exact cost for the service of landing and take-off of each aircraft type.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.263-271
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• 2008

This article considers how the rail track charges of the advanced countries are performed and derived political implication to Korail. In case of North America and Japan, rail track charges are being decided to collect the infrastructure maintenance cost. In European countries, the separation of infrastructure and operation is realized and the railroad track charges are based on MC+ principle. On the other hand, Korail is paying construction cost of KTX as well as maintenance cost in Korea. As for this, railroad reform including rail track charging should be reconsidered.

• Electronics and Telecommunications Trends
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• v.23 no.6
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• pp.2-11
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• 2008

태양전지는 태양광을 직접 전기로 변환하는 반도체 소자이다. 태양전지는 효율과 신뢰성이 높은 동시에 저렴한 비용으로 생산할 수 있어야 경제성을 확보할 수 있다. 박막형 태양전지는 제조과정에 에너지가 적게 소요되므로 짧은 기간 내에 투자한 비용과 에너지를 회수할 수 있을 뿐 아니라, 소재 비용도 대폭 줄일 수 있다. 국내에서는 아직 1세대 결정형 실리콘 태양전지 산업이 주류를 이루고 있으며 2세대 기술은 초기 단계에 있으나, 이와 유사한 공정을 사용하는 대면적 디스플레이 생산 설비 및 기술을 기반으로 협력 체제를 구축하여 연구개발을 촉진함으로써 빠른 시일 내에 차세대 태양광 발전 시장에서의 경쟁력을 확보할 수 있을 것으로 기대된다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.20 no.4
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• pp.4784-4794
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• 1978

주정부가 대규모의 관개용수공급의 책임을 지고 있는 인도와 같은 개발도상국에서는 관개용수의 가격을 결정하는 문제는 특별한 중요성을 갖고 있다. 한편으로는 전체 주민중 일부 몽리민에게 돌아가는 관개 혜택중에서 관개사업 비용과 앞으로의 용수원 개발을 위한 자금을 회수해야 하며 또 다른 한편으로는 경작자로 하여금 관개수 사용을 통해서 더 많은 생산을 유도케 하는 인센티브를 주어야 한다. 본보고문은 인도의 각주 및 세계 각국의 현행 관개수가격 제도를 일별하고 함리적인 가격 구조를 위한 원칙을 논의코져 한다. 연간비용의 구성 대체 수원비용의 원측, 수익의 개념 및 이의 평가등을 다루었다. 관개수의 가격 구조를 함수화 하기 위해 고려 되어야 할 중요 내용을 총망라하고 필요한 자료를 제시하였다. 가격의 산정방법, 지역, 작물 및 계절이 달라지는데 따라 균등 또는 비균등 가격을 적용할 것인지를 결정하는데 고려되어야 할 사항, 장려가격 및 차등가격의 문제점, 몽리구역내의 모든 경작자에게 부과할 관개세의 문제점도 포함하였다. 결론적으로 가격의 주기적인 조정의 필요성과 전반적인 문제점을 가장 합리적으로 다룰 수 있는 전담 기구의 필요성을 다루었다. 합리적인 가격 결정을 위해 수집되는 자료는 개설 관개사업의 경제적 평가를 위해서도 이용 될 수 있을 것임을 부기해둔다.

• Resources Recycling
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• v.33 no.3
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• pp.3-11
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• 2024

This study addressed the cost structure of metallurgical plants for vanadium recovery or production, which were previously planned or implemented. Vanadium metallurgy consists of several sub-processes such as such as pretreatment, roasting, leaching, precipitation, and filtration, in order to finally produce vanadium pentoxide. Here, lots of costs should be spent for such plants, in which these costs are largely divided into CAPEX (Capital Expenditure) and OPEX (Operational Expenditure). As a result, the capacities (feed input rates) and vanadium contents are various along the target projects for this study. However, final production rates and grades of vanadium pentoxide showed relatively small differences. In addition, a noticeable correlation is found between capacities and specific operating costs, in that a steadily decreasing trend is described with a non-linear curve with around -0.3 power. Therefore, for the plant capacity below 100,000 tons per year, the specific operating cost rapidly decreases as the capacity increases, whereas the cost remains relatively stable in the range of 0.6 to 1.2 million tons per year of the capacity. From a technical perspective, effective optimization of the metallurgical process plant can be achieved by improving vanadium recovery rate in the pre-treatment and/or roasting-leaching processes. Finally, the results of this study should be updated through future research with on-going field verification and further detailed cost analysis.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.570-579
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• 2016

This study proposes a concept of Stepwise Transfer Coefficient(STC) which implies greater transfer cost with increasing the number of transfers. Thus, the public transport information system provides the choice sets of travel routes by the consideration of not only transportation time but also the optimum number of transfers. However, path choice problems that involve STC are found to include non additive cost, which requires additional route enumeration works. Discussions on route enumeration in actual transportation networks is very complicated, thereby warranting a theoretical examination of route search considering STC. From these points of view, this study results in a probability based transit trip assignment model including STC. This research also uses incoming link based entire route deletion method. The entire route deletion method proposed herein simplifies construction of an aggregation of possible routes by theoretically supporting the process of enumeration of the different routes from origin to destination. Conclusively, the STC reflected route based logit model is proposed as a public transportation transit trip assignment model.

• Korean Journal of Construction Engineering and Management
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• v.6 no.2 s.24
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• pp.129-138
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• 2005

The purpose of this study is to assess economic effects for an advanced technology-based HVAC system. The study has been performed using LCC technique for the economic analysis. Data for LCC analysis are collected from estimation and interview of estimators and maintenance experts of buildings. Based on the LCC analysis, the economic effect of a new HVAC system has been predicted as follows : for the investment during 15 years of study period, (1) $21.6\%$ of LCC saving is predicted, (2) return rate for the investment is 4.8 times in case of new construction, and 14.4 times in case of building remodelling.