• KIEE International Transactions on Electrophysics and Applications
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• 제3C권5호
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• pp.189-193
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• 2003

Initial irreversible capacity (IIC) can be defined by means of the initial intercalation Ah efficiency (IIE) and the initial irreversible specific capacity at the surface (IICs) with the linear-fit range of the intercalation so as to precisely express the irreversibility of an electrode-electrolyte system. Their relationship was IIC = Qc - Q$_{D}$ = (IIE$^{-1}$ - 1) Q$_{D}$ + IICs in the linear-fit range of IIE. Here, Qc and Qd signify charge and discharge capacity, respectively, based on a complete lithium ion battery cell. Charge indicates lithium insertion to carbon anode. Two terms of IIE and IICs depended on the types of active materials and compositions of the electrode and electrolyte but did not change with charging state. In an ideal electrode-electrolyte system, IIE and IICs would be 100%, 0 mAh/g for the electrode and mAh for the cell, respectively. These properties can be easily obtained by the Gradual Increasing of State of Charge (GISOC).OC).

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1-5
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• 2009

Recently, as a method of green-development and reduction of carbon dioxide emission, increased interest has been focused on a railway. Furthermore, an intensive study has been processed on capabilities of maintenance activities, economic efficiency of maintenance on rail structure and a design of railway structure as well as the development of materials. The purpose of this paper is to develop a deteriorated model of PC Beam Bridge due to timely changes and maintenance activities. Typically, there is definite difference between maintained bridges and non-maintained bridges. As a result of proper maintenance activity, a life time of a structure can be enhanced. In this study, we will research and analyze structures with ongoing maintenance. We will also process same procedures on structures without maintenance. Therefore, we can establish the significant role in a conditional change of a structure. Based on a study, we accomplish the development of a condition-deteriorated model. To develop deteriorated model of PC Beam Bridge, We apply Marcov Theory and develop a transition probability to show the life time of bridge. This study will provide a great benefit to decision making for maintenance activities on the railway bridges for future.

• Composites Research
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• 제25권1호
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• pp.1-8
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• 2012

본 논문에서는 다공성 복합재료의 열탄성 거동 예측을 위하여 미시역학적 유한요소 해석을 통해 기공 탄성 인자를 측정하였다. 먼저 기공 압력에 의한 복합재료의 응력 및 변형 상태를 기술하기 위해서 구성 방정식에 기공 탄성 인자를 도입하였다. 기공 탄성 인자의 산출에 필요한 기공 압력에 의한 팽창 변형도와 기공 형성에 따른 균질화 탄성 계수의 저하를 측정하였다. 기공의 형상, 크기, 배열 형태에 따른 이차원 대표 체적 요소의 모델링과 유한요소 해석을 수행하였다. 기공도, 재료 이 방성이 기공 탄성 인자에 미치는 영향과 기공 압력에 따른 변형 에너지 밀도 분포를 살펴보았다. 또한, 측정된 기공 탄성 인자의 유용성을 검토하기 위하여 탄소/페놀릭 복합재료의 열탄성 거동을 예측하였다.

• 한국생산제조학회지
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• 제20권3호
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• pp.219-224
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• 2011

Aluminum or CFRP is representative one of the lightweight materials. Collapse behavior of Al/CFRP square structural member was evaluated in this study based on the respective collapse behavior of aluminum and CFRP member. Al/CFRP square structural members were manufactured by wrapping CFRP prepreg sheets outside the aluminum hollow members in the autoclave. Because the CFRP is an anisotropic material with mechanical properties, The Al/CFRP square structural members stacked at different angles(${\pm}15^{\circ}$, ${\pm}45^{\circ}$, ${\pm}90^{\circ}$, $90^{\circ}/0^{\circ}$ and $0^{\circ}/90^{\circ}$ where the direction on $0^{\circ}$ coincides with the axis of the member) and interface numbers(2, 3, 4, 6 and 7). The axial impact collapse tests were carried out for each section members. Collapse mode and energy absorption characteristics of the each member were analyzed.

• 자원리싸이클링
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• 제25권3호
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• pp.82-87
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• 2016

차세대 이차전지로서 주목받고 있는 리튬-공기 전지와 소듐-공기 전지를 에테류계 전해질을 이용하였을 시 방전 후 생성물을 분석 하였다. FESEM을 통하여 확인한 결과 리튬-공기 전지와 소듐-전지의 방전 후 생성된 입자의 형태는 좁쌀 모양을 보였으며, 두 전지 시스템에서 큰 차이를 보이지 않았다. 하지만 XRD를 통하여 확인 하였을 시 리튬-공기 전지는 비정질 형태의 $Li_2O_2$ 그리고 소듐-공기에서는 결정질의 $NaO_2$가 생성되는 것을 확인 할 수 있었다. 본 연구를 통하여 차세대 전지 시스템으로 주목받고 있는 리튬-공기 전지와 소듐-공기 전지의 기본적인 구동 원리를 이해할 수 있었다.

• 소성∙가공
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• 제24권3호
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• pp.155-160
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• 2015

One of the most important aspects in multi-stage shape drawing is the proper design of the intermediate dies especially to provide adequate metal distribution. In the current study, a method for designing the intermediate dies has been developed to manufacture hollow linear motion guide rails by multi-stage shape drawing. The design method is based on the modified virtual die method. The effectiveness of the proposed design method was verified by FE-simulations and experiments using Mn55Cr carbon steel. From the results of the FE-simulations and the experiments, the proposed design method led to a drawn product with a sound shape. The dimensional tolerances of the product were within the allowable specified tolerances.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.220-223
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• 2005

The rapid prototyping (RP) technology has been advanced for various applications such as verification of design, functional test. However, many RP machines still have low accuracy and limitation of applications for various materials. In this research, a hybrid RP system was developed to improve precision of micro parts. This hybrid system consists of deposition and material removal process by mechanical micro machining to fabricate nano composites using photo-curable polymer resin with various nano particles. In this work, using hybrid RP process with Multi-Walled Carbon Nano Tube (MWCNT) and hydroxyapatite, micro parts were fabricated. The precision of parts was evaluated based on the original CAD design, and to see the effect of nano particles on mechanical properties, tensile strength was measured. From the results of experiments, it was confirmed that the part made by hybrid process had higher precision, and the addition of nano particles improved mechanical properties.

• Archives of Pharmacal Research
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• 제20권6호
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• pp.620-628
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• 1997

6-Aryl-5-cyano-4-pyrimidinon-2-thione derivatives 1a-c reacted with ethyl iodide to give the corresponded 2-S-ethylpyrimidin-4-one-derivatives 2a-c. Compounds 2a-c was, in turn, reacted with hydrazine hydrate to give the sulfur free reaction products, 3a-c. These reaction products were taken as the starting materials for the synthesis of several newly synthesized heterocyclic derivatives. Reactions with several halogenated ketones, esters, chloroacetic acid and chloroacetamide give pyrimidotriazines 8,12 and 15 while their reactions with formic acid, acetic acid and carbon disulfide gave the corresponded triazolopyrimidines 17 and 21. The reaction with both acetyl acetone and ethylacetoacetate gave the corresponded 2-$(3^{I},5^{I}-dimethyl-1^{I}-pyrazoly$pyrimidine derivatives 20a-c and 24a-c respectively while the reaction with cinnamonitriles 25a-h afforded the corresponded aryl hydrazopyrimidines 27a-f. The structure of these reaction products were eatablished based on both elemental anlayses and spectral data studies.

• Computers and Concrete
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• 제24권5호
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• pp.453-458
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• 2019

Today, concrete remains the most important, durable, and reliable material that has been used in the construction sector, making it the most commonly used material after water. However, cement continues to exert many negative effects on the environment, including the production of carbon dioxide (CO2), which pollutes the atmosphere. Cement production is costly, and it also consumes energy and natural non- renewable resources, which are critical for sustainability. These factors represent the motivation for researchers to examine the various alternatives that can reduce the effects on the environment, natural resources, and energy consumption and enhance the mechanical properties of concrete. Geopolymer is one alternative that has been investigated; this can be produced using aluminosilicate materials such as low calcium (class F) FA, Ultra-Fine GGBS, and high calcium FA (class C, which are available worldwide as industrial, agricultural byproducts.). It has a high percentage of silica and alumina, which react with alkaline solution (activators). Aluminosilicate gel, which forms as a result of this reaction, is an effective binding material for the concrete. This paper presents an up-to-date review regarding the important engineering properties of geopolymer formed by FA and slag binders; the findings demonstrate that this type of geopolymer could be an adequate alternative to ordinary Portland cement (OPC). Due to the significant positive mechanical properties of slag-FA geopolymer cements and their positive effects on the environment, it represents a material that could potentially be used in the construction industry.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.460-468
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• 2008

Recent activities on the scramjet and rocket-ramjet combined-cycle engine of Japan Aerospace Exploration Agency(JAXA) are herein presented. The scramjet engines and combined-cycle engines have been studied in the world and JAXA has also studied such the engines experimentally, numerically and conceptually. Based on the studies, 2 to 3 m long, hydrogen-fueled engine models were designed and tested at the Ramjet Engine Test Facility(RJTF) and the High Enthalpy Shock Tunnel(HIEST). A scramjet engine model was tested in Mach 10 to 14 flight condition at HIEST. A 3 m long scramjet engine model was designed to reduce a dissociation energy loss in a high temperature condition. Drag reduction by a tangential injection and two ways of a transverse fuel injection were examined. Combustor model tests at three operating modes of the combined-cycle engine were conducted, demonstrating the combustor operation and producing data for the engine design at each mode. Aerodynamic engine model tests were conducted in a transonic wind tunnel, demonstrating the engine operation in the ejector-jet mode. A 3 m long combined-cycle engine model has been tested in the ejector-jet mode and the ramjet mode since March 2007. Carbon composite material was examined for application to the engines. Production of the cooling channel on a nickel alloy plate succeeded by the electro-chemical etching.