• Composites Research
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• 제34권5호
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• pp.269-276
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• 2021

프리프레그 압축성형(PCM, Prepreg Compression Molding) 공정은 고품질 CFRP(Carbon Fiber Reinforced Plastic) 제품을 제조할 수 있는 고속성형기술이다. 오토클레이브 공정에 비해 폐기물 발생이 적고 사이클타임을 크게 줄일 수 있어 항공우주 및 자동차 산업에서 다양한 연구가 진행되고 있다. 본 연구에서는 PCM 공정의 품질을 높이기 위해 프리프레그의 경화거동을 따라 프레스의 압축압력을 단계별로 증가시키는 성형법에 대해 연구하였고, 이러한 다단 압축 성형법이 우수한 품질의 CFRP 제품을 생산하고 사이클타임을 단축할 수 있는 좋은 수단임을 확인하였다. 그리고 상온에서 적층한 프리프레그를 금형에 투입하여 예열과 성형을 동시에 함으로써 별도의 예열 공정 없이 제품을 성형할 수 있었다. 또한 평판 성형에 최적화된 공정조건을 3차원 형상물에 동일하게 적용한 결과 외관상 평판과 유사한 제품을 공정조건 수립 과정 없이 만들 수 있었다.

• 한국재료학회지
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• 제13권2호
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• pp.126-132
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• 2003

In order to evaluate the corrosion resistance at the anode side separator for molten carbonate fuel cell, STS316 and SACC-STS316 (chromium and aluminum were simultaneously deposited by diffusion into STS316 authentic stainless steel substrate by pack-cementation process) were applied as the separator material. In case of STS316, corrosion proceeded via three steps ; a formation step of corrosion product until stable corrosion product, a protection step against corrosion until breakaway occurs, a advance step of corrosion after breakaway. Especially, STS316 would be impossible to use the separator without suitable surface modification because of rapid corrosion rate after formation of corrosion product, occurs the severe problem on stability of cell during long-time operation. Whereas, SACC-STS316 was showed more effective corrosion resistance than the present separator, STS316 due to the intermetallic compound layer such as NiAl, Ni3Al formed on the surface of STS316 specimen. And it is anticipated that, in order to use SACC-STS316 alternative separator at the anode side, coating process, which can lead to dense coating layer, has to be developed, and by suitable pre-treatment before using it, very effective corrosion resistance will be achieved.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.81-84
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• 2001

An inverse finite element approach is employed for more capability to design the optimum blank shape from the desired final shape with small amount of computation time and effort. In some drawing or stamping simulation with inverse method, it is difficult to apply inverse scheme due to the large aspect ratio or steep vertical angle of inclination. The reason is that initial guesses are hard to make out with present method for those cases. In this paper, a direct mesh marring scheme to generate initial guess on the sliding constraint surface described by finite element patches is suggested for one step inverse analysis to calculate initial blank shape. Radial type mapping is adopted for the simulation of rectangular cup drawing process with large aspect ratio and parallel type mapping for the simulation of S-Rail forming process with steep vertical angle of inclination.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 추계학술대회 논문집 전력기술부문
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• pp.271-273
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• 2002

This paper proposes a process that determines inter-area TTC(total transfer capability) by supplementing the existing process. The process is composed of three steps, which is composed of (a) estimation of input data, (b) selection of contingencies, and (c) determination of the transfer capability. In this study, one step is added to develop the methodology that enhances the TTC.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 고액공존금속의 성형기술 심포지엄
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• pp.16-27
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• 1997

A semi-solid forming has a lot of advantages compared to the die casting, squeeze costing and convenctional forging, therefore, semi-solid forming process are now becoming of industial interest for the production of metal components and metal matrix composites. However, the material behaviour in the semi-solid temperature range is not sufficiently known although it controls the whole process through forces and geometry evolutions bcause the behaviour of metal slurries is complex. The semi-solid materials(SSM) fabricated under electric-magnetic stirring condition is necessary to be applicate in forming process. A reheating conditions were studied with the reheating time, holing time and reheating temperatures. The microstructure of SSM (which specimen size:d 40${\times}$i60) on condition of heating time 10min and heating temperature 590$^{\circ}C$ is most globular and finest one. The microstructure of SSM(specimen size:d75${\times}$i60) reheated under the three step reheating conditions is most globular and finest.

• 한국CDE학회논문집
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• 제6권4호
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• pp.263-270
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• 2001

In stamping-die manufacturing, the first step is to build die patterns for lost wax casting process. A recent industry trend is to manufacture the die pattern using 3-axis NC machining. This study identifies technical considerations of the pattern machining caused by the characteristics of Styrofoam material, and proposes technical methods related to establishing a process plan and generating tool paths for optimizing the pattern machining. In this paper, the process plan includes the fellowing three items: 1) deter-mining a global machining sequence-a sequence of profile, top, bottom machining and two set-ups, 2) extracting machining features from a pattern model and merging them, and 3) determining a machining sequence of machining features. To each machining feature, this study determines the machining start point, generates the approach tool path, and proposes a tool path linking method fur reducing the distance of the cutter rapid motion. Finally, a smooth tool path generation and an automatic feedrate adjustment (AFA) method are introduced far raising the machining efficiency.

• 대한소아치과학회지
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• 제49권3호
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• pp.264-273
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• 2022

치과에서 사용하는 재료들의 물성의 발달로 인하여 브라켓과 치아 사이의 결합 능력도 크게 향상되었다. 그러나 소아치과 영역에서와 같이 환자의 협조를 기대하기 어렵거나, 수분 격리가 제대로 이루어지지 않을 경우 기대하는 효과에 미치지 못하는 결합강도를 보여 줄 수 있다. 본 연구의 목적은 세 가지의 접착 술식을 비교하여 브라켓의 전단 접착 강도를 평가하고, 임상적으로 유의한 차이가 존재하는지 비교하는 것이다. 우식증이나 수복물이 없는 상, 하악 소구치 60개 치아를 대상으로 하였다. Group I은 대조군으로서 기존의 3 step 접착 방식에 따라 브라켓을 부착하였고, Group II는 self-etching primer system을 이용하여 부착하였다. Group III는 self-priming adhesive를 이용하여 브라켓을 부착하였다. 각 group의 전단 결합 강도를 측정하고 접착제 잔류지수(ARI)를 기록하였다. 각 group I, II, III의 평균 전단 결합 강도는 14.69 MPa, 11.21 MPa 그리고 12.21 MPa로 측정되었다. Group I과 II, group I과 III에서만 유의한 차이가 존재하였으며(p < 0.05), ARI 값은 모든 group에서 유의한 차이가 존재하지 않았다.

• 한국물환경학회지
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• 제23권3호
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• pp.303-308
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• 2007

Three types dyeing wastewater (dark, medium, light color) discharged from cotton textile dyeing with reactive dye was collected at each step of process. Each process dying wastewater was analyzed and treated by ionized gas. The analysis focused on $COD_{Cr}$, SS and color. Bleaching & scouring process wastewater has the highest $COD_{Cr}$ value in the three type dyeing wastewater. SS shows the highest value at dyeing process wastewater in dark and medium color but light color has at finishing process wastewater. The result of process wastewater treatment by ionized gas was that the ionized gas was effective in $COD_{Cr}$ removing of bleaching & scouring process and finishing process wastewater but was not good at dyeing process wastewater. From that result it is estimated that the ionized gas could not work in opening the aromatic ring and react only in aliphatic component of the molecule. Because the surfactants contained in bleaching & scouring process and finishing process wastewater have only one aromatic ring in its molecular structure, in contrast with the reactive dye compounds consist of aromatic rings great part of its molecular structure. The color almost removed in 1.5 hrs reaction time but $COD_{Cr}$ removal effiency was only 30.7% through 3hrs in 1500 mL of total dyeing wastewater treated by 10 L/min ionized gas.

• 간호행정학회지
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• 제4권2호
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• pp.419-437
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• 1998

Nurses use a nursing process. that is a scientific approach method. in order to understand the clients' condition and to solve their problems. Professional nurses have accepted the nursing process as a standard framework for nursing activities, and the first step of the nursing process is nursing assessment. The purpose of this study was to develop a nursing assessment tool for emergency patients. Assessment is a first step in the nursing process, and scientific assessment helps to better understand the patients. Thus the development of an assessment tool for emergency patients will improve of nursing quality and advance to efficacy of emergency room(ER) management. The study involved the development of a conceptual framework, preliminary tool, content validity verification process. and reliability verification process. The conceptual framework was developed through a review of the literature. and preliminary tool was developed from the conceptual framework that based on care flow sheet' developed James A. Haley. The preliminary tool was evaluated for validity and reliability by seven experts, one ER nurse manager, two ER head nurses, two emergency medicine doctors. and two ER charge nurses and by ten nurses with one to five year careers in ER nursing. The results of this study was as follows 1. The conceptual framework which was developed was composed of three parts. They were triage criteria, first assessment and secondary assessment. 2. The preliminary tool which was developed had 31 items based on the conceptual framework. 3. To test expert validity a 4-point scale was used. items which had gained 3-4 points from six persons of the seven experts were selected. All 31 items from the preliminary tool were selected. 4. The reliability test was done by ten nurses educated in the use of the assessment tool. Two pairs of nurses simultaneously assessed the same patients. A total agreement percentile was calculated and result was 87.3% agreement. 5. After the validity and reliability testing. the final emergency patient nursing assessment tool was finalized with 31 items. and a check-list for the responses. This study concludes that the tool which was developed is both valid and reliable will advance quality care for emergency patients. This emergency nursing assessment tool was also found to be an adequate tool for assessment of emergency patients.

• 정보처리학회논문지D
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• 제11D권1호
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• pp.183-194
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• 2004

기존의 연구비 관리업무는 예산계획, 예산편성 및 예산정산 부분으로 관리됨으로써 여러 가지 문제점이 발생되었다. 이러한 문제점을 해결하고 연구비의 안정적인 확보와 효율적인 운영 및 투명한 집행을 위하여 연구비의 통합관리가 절실하게 요구되고있는 실정이다. 최근의 이러한 추세를 반영하여 기존의 시스템 통합업체(Inmon, IBM)의 데이터 웨어하우스 개발 프로세스에 대해서 연구한 결과 Inmon의 데이터 웨어하우스 개발 프로세스에서는 고전적인 개발주기 기법으로 단계적이며 순차적인 접근방법을 이용한다. 이로 인해 개발단계에서 중복되어지는 부분이 나타나게 되어 각 단계의 진행과정에서 그 이전단계로 피드백이 요청되는 심각한 문제를 유발하게 된다. 또한, IBM의 데이터 웨어하우스 개발 프로세스에서는 개발 프로세스가 수행되는 동안 기능과 데이터가 분리되어 어떤 기능이 데이터를 참조하고 수정하는지 안기 어려운 문제점이 발생되었다. 따라서, 된 논문에서는 이러한 문제점들을 해결하고자 계획 덴 분석단계, 설계단계, 구현 및 시험단계에서 UML을 적용한 엔터프라이즈 환경의 연구비 통합관리 데이터 웨어하우스 개발 프로세스를 제안하였다. 본 논문에서는 기존의 예산계획 DB, 예산편성 DB, 예산정산 DB의 데이터를 이용하여 사용자가 인하는 정보를 찾아주는 역할을 정보검색 에이전트에서 수행한다. 또한, 정보통합 에이전트에서는 정보검색 에이전트에서 수집한 데이터를 추출, 전송, 가공, 로딩 하여 통합 데이터베이스에 저장한다. 결과적으로, 정보통합 에이전트에서는 다수의 정보소스를 사용자가 하나하나 접근하여 검사하는 노력을 줄여주고 사용자에게 불필요하다고 판단되는 데이터를 걸러주는 역할을 수행한다. 이러한 결과로 사용자의 요구사항을 최대한 반영하여 연구비 관리정책의 수립에 필요한 다양한 형태의 의사결정 지원정보를 제공할 수 있도록 하였다. 최종 사용자에게는 원하는 분석정보를 신속하게 접근하여 단편적인 관점보다는 종합적인 관점에서 다양한 분석자료를 제공받을 수 있도록 하였다. 또한, 3개의 시스템을 하나로 통합한 결과 데이터의 공유, 시스템 통합, 운영비용 절감, 의사결정 지원환경을 단순화시키는 효과를 제공하였다.