• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1397-1405
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• 2009

In recent decades, exergy analysis has been holding spotlight as a useful tool in the design, assessment, optimization, and improvement of energy system. This paper presents the results of the energy and exergy analysis of a steam turbine cogeneration system for industrial complex using two efficiency concepts of conventional one and exergetic one. In order to obtain the destroyed exergy of each component, mathematical analysis is conducted by using exergy balance and the second law of thermodynamics, according as the parameters are changed, such as the ratio of returned process steam, process steam supplied, temperature and pressure of boiler and power. The computer program developed in this study can determine the efficiencies and exergy destroyed at each component of cogeneration system. As a result of this study, a component having the largest destroyed exergy was boiler. And closed and opened feedwater heater had the lowest one. The affects to the cogeneration system due to the variation of process steam flow and return rate of condensed water is shown that the total electric power efficiency(${\eta}_E$) is decreased as increasing the return rate of condensed water under constant process steam flow. As the boiler pressure is increased for the more production of electricity, the efficiency of cogeneration system was decreased.

• Design & Manufacturing
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• 제14권3호
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• pp.37-43
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• 2020

Progressive drawing processing is one of the manufacturing processes used to mass-produce a variety of products on the industrial site. In this study, the goal is to achieve a uniform product thickness of at least 1.3mm by reducing the wall thickness of the coupler parts used in automotive air conditioning systems to within 15% using A5052-H32 materials. The progressive die was designed using Blank's law of volume invariance. Due to the characteristics of the drawing process, the material thickness in the punch R part decreases and the thickness in the die R part increases. When designing the progressive die of the coupler part, an ironing method, a push back method, and a stand-alone die pad method were applied to each process to design a mold in consideration of the drawing rate and to artificially adjust the thickness change. The suitability of the method used in die design was investigated by measuring the thickness change of forming parts for each process. In the final part, it was confirmed that the thickness measurement values of the five regions of a radial line were implemented as 1.34-1.36 mm.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.475-480
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• 2002

The reliability of the solder joint is affected by type and extent of the interfacial reaction between solder and substrates. Therefore, understanding of intermetallic compounds produced by soldering in electronic packaging is essential. In-based alloys have been favored bonding devices that demand low soldering temperatures. For photonic and fiber optics packaging, m-based solders have become increasingly attractive as a soldering material candidate due to its ductility. In the present work, the interfacial reactions between indium solder and bare Cu Substrate are investigated. For the identification of intermetallic compounds, both Scanning Electron Microscopy(SEM) and X-Ray Diffraction(XRD) were employed. Experimental results showed that the intermetallic compounds, such as Cu$_{11}$In$_{9}$ was observed for bare Cu substrate. Additionally, the growth rate of these intermetallic compounds was increased with the reaction temperature and time. We found that the growth of the intermetallic compound follows the parabolic law, which indicates that the growth is diffusion-controlled.d.

• 환경영향평가
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• 제18권4호
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• pp.235-243
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• 2009

Wetlands considered to be an important natural resources because they provide biodiversity and habitat for species to breed and survive. In this regard, many countries in the world provide wetlands and have policies and laws to protect them. In Korea we hosted RAMSAR COP-10 at Changwon in 2008 representing Korea's endeavor to wetland protection. But, in the process of development Wetlands are easy target to be lost due its easy access and the laws and regulations to protect them are relatively weak. Thus, this research focused on the introduction of No Wetland Loss(NWL) and we can achieve wetland protection in the economy market ways. Thus, NWL should consider 1) a clear definition of NWL and harmony and consensus of introduction of NWL, 2) considering most wetlands be private we need a financial support for securing wetlands, 3) inventories for wetlands in Korea, draw a line of demarcation, technic to evaluate wetlands, 4) wetland restoration considering function of ecosystem not total amount of wetlands. Wetland protection should be a part of Basic Law of Water Management which in its progress and we need further studies on wetland protection because of watershed management, deserted agricultural paddies, etc.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1992년도 가을학술발표회 논문집
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• pp.55-60
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• 1992

Hydraulically filled ground is formed by the settling of soil grains from the mixture of soil grains and water. It was generally known that the settling speed of the soil grains in governed by Stokes low. In the case of clayed dredged material, the shape of soil grains is not round, the surface of the soil grains is relatively large compared to the weight of soil grains and inter-grain ionic force is relatively large compared to the wight of soil grains. By this reason the settling and consolidation behavior of hydraulically filled quite different from that of Stokes law. This study investigated the settling and consolidation behavior of hydraulically filled materials of Yeochon industrial complex by large scale laboratory settling & consolidation container. The test results showed tat actual settling speed of soil grains in quite large compared to that of Stokes law. It was turned out that this phenomenon was due to the aggregation of soil grains. Also, it was truned out that the void ration and water content after the completion of settling process was 8.7 and 322% respectively. The consolidtion settlement of clayey hydraulic fill material was predicated better by "incremental small strain" consolidation concept than classical Terzaghj's consolidation concept (infinitesimal strain).

• 무역상무연구
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• 제63권
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• pp.25-62
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• 2014

Avoidance refers to the process of terminating a contract because of a non-performance. It implies the right of the aggrieved party to refuse to accept further performance by the other side and to refuse to perform one's own counter-obligations, on a permanent basis. The 1980 U.N. Convention on the International Sale of Goods, hereinafter 'CISG', regulates in Arts. 81-84 the effects of avoidance. The primary effect is that prescribed in Art. 81.1 CISG: both parties are released from their obligations under the contract, subject to any damages which may be due. As seen, the CISG deals with the legal consequences of avoidance, including restitutionary claims. However, a closer look to CISG provisions on restitution reveals that certain matters are left open. For instance, the CISG leaves open questions such as the costs, place and time where restitution is to be made. In this particular, the Convention remains silent as to the consequences of a delayed or refused restitution or the buyer's liability when the goods are damaged or destroyed after the avoidance. In light of the above, the present article attempts to determine the extent to which the modes of restitution are regulated in the CISG and how possible gaps are to be filled.

• 무역상무연구
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• 제78권
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• pp.73-91
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• 2018

When existing trade creates a product, a series of processes is terminated when a seller or a buyer subscribes for transportation insurance and is guided through customs procedures according to the terms of the sales contract and then receives payment for it. Training practical Trade kowhow is also educated focusing on the procedures of these contracts. A new paradigm of the fourth industrial revolution was launched in the development of information communication technology and computer technology. Also, due to the Xinhuo tradeism triggered by the United States, the risk of commodity trading is further increasing. Currently, trade practical education of university and industry is carried out for most lecture and discussion. Since 2014, the curriculumof the department of trade has been increasingly managed by the NCS process. The curriculumof the department of trade department has the advantage of being managed in consideration of the characteristics of the company that wishes to find employment and the level of work content. Standardized, the curriculumcan faithfully reflect the characteristics of the company and the level of the work content. In the new era, a new educational method that reflects the trend of the 4th industrial revolution era is necessary. In this research, we propose that service trade practical education should be educated mainly on contracts, not on procedural basis as with traditional commodity trade education.

• Advances in concrete construction
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• 제7권4호
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• pp.203-210
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• 2019

Concrete structures in marine environment are susceptible to chloride attack, where chloride diffusion results in the corrosion of steel bar and further lead to the cracking of concrete cover. This process causes structural deterioration and affects the response of concrete structures to different forms of loading. This paper presents the use of ABAQUS Finite Element Software in simulating the processes involved in concrete's structural degradation from chloride diffusion to steel corrosion and concrete cover cracking. Fick's law was used for the chloride diffusion, while the mass loss from steel corrosion was obtained using Faraday's law. Pressure generated by steel corrosion product at the concrete-steel interface was modeled by applying uniform radial displacements, while concrete smeared cracking alongside the Extended Finite Element Method (XFEM) was used for concrete cover cracking simulation. Results show that, chloride concentration decreases with penetration depth, but increases with exposure time at the concrete-steel interface. Cracks initiate and propagate in the concrete cover as pressure caused by the steel corrosion product increases. Furthermore, the crack width increases with the exposure time on the surface of the concrete.

• 한국컴퓨터정보학회논문지
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• 제28권2호
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• pp.191-200
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• 2023

미국에서는 소수의 전문가에게 정치적 이해관계가 첨예하게 얽혀 있는 문제의 결정을 전적으로 위임하지 않고, 주민이 직접 주 교육위원회나 지역 교육위원회의 구성원으로 참여할 수 있는 미국의 교육정책결정 및 집행과정은 다양한 교육주체 간에 이견이나 법령해석 차이 등으로 인해 발생할 수 있는 갈등과 분쟁을 사전에 예방하는 역할을 수행했다고 추정할 수 있다. 이러한 미국의 합의제는 현재 교육감 1인에게 과도하게 좌우되어 다양한 교육주체 간의 갈등이 발생하고 있는 우리나라 지방교육행정체제에 대한 보완점을 시사하는 것이다.

• Steel and Composite Structures
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• 제23권1호
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• pp.1-16
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• 2017

This paper is presented to solve the buckling problem of functionally graded truncated conical shells subjected to displacement-dependent pressure which remains normal to the shell middle surface throughout the deformation process by the semi-analytical finite strip method. Material properties are assumed to be temperature dependent, and varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The governing equations are derived based on first-order shear deformation theory which accounts for through thickness shear flexibility with Sanders-type of kinematic nonlinearity. The element linear and geometric stiffness matrices are obtained using virtual work expression for functionally graded materials. The load stiffness also called pressure stiffness matrix which accounts for variation of load direction is derived for each strip and after assembling, global load stiffness matrix of the shell which may be un-symmetric is formed. The un-symmetric parts which are due to load non-uniformity and unconstrained boundaries have been separated. A detailed parametric study is carried out to quantify the effects of power-law index of functional graded material and shell geometry variations on the difference between follower and non-follower lateral buckling pressures. The results indicate that considering pressure stiffness which arises from follower action of pressure causes considerable reduction in estimating buckling pressure.