FEM을 이용한 원형단면 CFRP 구조부재의 계면수 변화에 따른 압궤 특성 연구

김희성 조선대학교 일반대학원 2018 국내석사

Global warming is one of the most serious global environmental problems that threaten human society and natural ecosystems. The average temperature of the earth rises every year because of greenhouse gases such as carbon dioxide(CO2), methane(CH4), and nitrogen dioxide(N2O). It constantly caused losses of material and economic by climate changes. As a result, the most countries actively have provided solutions and fulfilled their obligations through not only the Kyoto Protocol but the Paris Protocol. As global attention such these, many countries tightened fuel economy regulations then this has become an important issue to determine the survival of the automotive industry. In addition, "Dieselgate" which caused by the german automobile manufacturers in November 2015 has spread the negative perception of diesel engines. For this reason, the automotive industry has focused on developing lightweight materials to increase engine efficiency. Therefore, CFRP(Carbon Fiber Reinforced Plastic) having light weight, excellent mechanical properties, and environment friendliness has recently attracted attention. However, CFRP consisting of carbon fiber and resin, it is so complicated and the mechanical properties changed depending on the fiber orientation angle. Additionally since it is elastic-brittle materials and the failure happen suddenly, the prediction of failure is too difficult. Nevertheless CFRP has been widely researched in various industries including the aerospace industry under leader of developed countries such as the United States and Europe. But, almost of study on CFRP has proceeded through the method depending on a experimental approach. Therefore, by performing the experiment and FEA(Finite Element Analysis) simultaneously, minimize the loss for temporary and financial. As the data obtained from these ways should be utilized appropriately for application of CFRP to some parts or structural member in demand for enough mechanical properties through characteristic evaluation. In this paper, structural members with CFRP according to number of interface and layered structure were manufactured and collapse experiment and simulation about them were carried out. Based on their results, the following conclusions were drawn. 1. In the case where the outermost fiber orientation of the structural member is 0°, the load-displacement graph of the experiment and simulation was partial converged as the collapse mode showed difference between experiment and simulation. On the other hand, in the case where the outermost fiber orientation of the structural member is 90°, the load-displacement graph of the simulation was similar to experiment and the structural member after collapse also showed comparatively similar. 2. The the experiment showed that tendency to the peak load is decreased as the number of interface of the structural member increased from 3 to 7, and the simulation was also same. The error rate of the experiment contrast simulation showed that the outermost fiber orientation is 0°, the structural member with interface of 7 was the highest with –96%, and the others showed the error rate ranging from -4% to 23%. 3. The the experiment showed that tendency to the absorbed energy is decreased as the number of interface of the structural member increased from 3 to 7. But in the simulation, the case of outermost fiber orientation of 0° showed increased and the case of outermost fiber orientation of 90° was same as the experiment. The error rate of the experiment contrast simulation showed that the outermost fiber orientation is 0°, the structural member with interface of 7 was the highest with –28%, and the others showed the error rate ranging from -4% to 8%.

고등학교 화학Ⅰ 및 화학Ⅱ 교과서 삽화와 탐구활동 분석 및 가시적인 실험으로의 개선방안 : 기체 단원 중심으로

김희성 인하대학교 교육대학원 2010 국내석사

본 연구는 제7차 교육과정 고등학교 각 8종의 화학Ⅰ 및 화학Ⅱ교과서에 제시된 '기체' 단원을 중심으로 삽화 및 탐구활동을 분석하고 현행 교과서 속의 삽화를 보완할 수 있는 시각자료로서 몇 가지의 실험을 개선한 것이다. 현행 교과서가 요구하는 인지수준과 고등학교 학생들의 인지수준이 일치해야 학습효과가 극대화된다는 전제하에 화학 교과서 속 삽화의 경향성을 분석하고, 이를 바탕으로 삽화를 보완할 수 있는 실험 개선을 통해, 눈에 보이지 않는 물질을 다루는 '기체' 단원의 개선을 연구 목적으로 한다. 연구 결과, 화학Ⅰ 및 화학Ⅱ교과서의 '기체' 단원에서 삽화 영역별로 마(도해 및 그림)영역 31.14%, 사(실험사진)영역 17.14%, 라(그래프)영역 15.14%의 순으로 제시되어 있었다. 또한 삽화 주제별로는 기체의 성질을 설명한 삽화가 32.29%로 가장 많았고, 보일의 법칙이 22.57%, 샤를의 법칙을 설명한 삽화는 22.00%였다. 화학Ⅱ의 어려운 개념일수록 삽화수가 적었고, 내용상 삽화가 부족하다고 생각되는 개념은 보일-샤를의 법칙(1.43%), 대기압(9.43%) 등이었다. 이에 대기압을 눈으로 확인할 수 있는 물기둥 실험 장치를 고안하고, 기존 스포이트 잠수부를 이용하여 샤를의 법칙 또한 설명할 수 있도록 방법을 개선하였다. 2007 개정교육과정을 토대로 화학Ⅰ 및 화학Ⅱ의 '기체' 단원 통합이 이루어질 예정이다. 형식적 조작기의 인지수준을 요구하는 삽화를 주로 제시하고 있는 현행 교과서의 분석과 개선을 토대로 새로운 교과서에서는 적절한 삽화와 탐구활동이 제시되기를 기대한다.

이중 슬릿 간섭 실험을 통한 박막의 두께와 굴절률 측정

김희성 부산대학교 대학원 2024 국내석사

이중 슬릿 간섭 실험을 이용하여 고분자 물질로 만든 박막의 두께와 굴절률, 그리고 물질의 색 분산을 측정하는 실험을 수행하였다. 633.0 nm의 파장을 갖는 He-Ne 레이저를 사용하여 두께와 굴절률을 측정하는 실험을 진행하였으며, 633.0 nm, 532.4 nm 그리고 440.3 nm의 파장을 갖는 레이저로 박막 물질의 색 분산을 측정하는 실험을 진행하였다. 박막 시료로는 Norland Products 사의 UV 경화성 고분자 NOA61을 용융 석영 유리(fused silica) 기판 위에 스핀 코팅하여 박막을 형성하였다. 이중 슬릿 회절 실험을 통해 박막이 만드는 위상차를 측정하였으며, 측정된 위상차를 통해 두께와 굴절률을 계산하였다. 측정된 결과를 검증된 방법인 도파로 결합법(프리즘 결합기)으로 측정한 결과와 비교하였으며, 두 방법으로 측정된 값이 1 % 내외의 오차가 있는 것을 확인하였다. 633.0 nm, 532.4 nm, 그리고 440.3 nm에서 이중 슬릿 회절 실험을 진행하여 각 파장에서 박막이 만드는 위상차를 측정하였다. 이를 통해 박막 물질의 Cauchy 식을 계산하였으며, 박막 물질의 아베 수를 계산하였다. 제작사의 Cauchy 식으로 박막 물질의 아베 수를 계산하였고, 이를 실험으로 구한 아베 수와 비교하였다. 두께와 굴절률의 측정 불확도는 두께는 20 nm, 굴절률은 0.004 로 계산되었다. 측정된 위상차를 이용하여 다른 파장의 굴절률을 소수점 네 번째 자리에서 오차를 가지고 구할 수 있었다.

급성신부전의 감별진단에 있어서 요산 및 요소 분획 배설율의 임상적 유용성

김희성 충북대학교 대학원 2006 국내석사

Background: Acute renal failure is a common problem in clinical practice. An early recognition of prerenal azotemia allows to correct reversible factors and good prognosis can be anticipated. Fractional excretion of sodium(FENa) has been known to discriminate between prerenal azotemia(PR) and acute tubular necrosis(ATN). But the usefullness of FENa is limited in some conditions such as nephrotic syndrome, liver cirrhosis, burn, sepsis, and severe metabolic alkalosis. FENa is also significantly influenced by diuretics and saline infusion. Fractional excretion of uric acid(FEUa) and fractional excretion of urea nitrogen(FEUn) have been known to be more sensitive and specific index in patients received diuretics. Thus, we evaluated the efficacy of FEUa and FEUn in differentiating between prerenal azotemia and acute tubular necrosis. Methods: Fifty five patients with acute renal failure who visited Chungbuk National University Hospital between January 1999 and April 2006 were enrolled. The urine and serum samples were serially collected initially, 24 hours and 48 hours later. It was reviewed whether they were managed with diuretics or saline replacement prior to visit. Acute renal failure was defined as serum creatinine above 1.5 mg/dl. The diagnosis of PR was established according to following criteria, 1) development of renal failure in the setting of extracellular volume depletion. and 2) normalization of serum creatinine within 5 days with correction of hemodynamic abnormality. ATN was defined as serum creatinine above 1.5 mg/dl persisted after correction of hemodynamic cause. Patch renal vasoconstriction was classified into ATN regardless of criteria. Subjects with glomerulonephritis or postrenal acute renal failure was excluded. Results: FENa(PR group: 1.9±2, ATN group: 6.1±6.1, P=0.001) were lower in PR than in ATN patients. FEUa(PR group: 15.7±12.5, ATN group: 24.2±13.4, P=0.019) and FEUn(PR group: 29.9±22.5, ATN group: 43.9±19.5, P=0.016) were lower in PR than in ATN patients as well. Renal failure index(PR group: 2.6±2.7, ATN group: 8.1±8.2, P=0.001) and urinary to plasma creatinine ratio(PR group: 28.8±26.4, ATN group: 13.7±12.3, P=0.013) were significantly different between two groups. When FENa was less than 1%, sensitivity and specificity for the detection of PR patients was 48% and 97%. A FEUa less than 15% and a FEUn less than 35% had the best sensitivity and specificity for PR patients(FEUa: 65% and 71%, FEUn: 68% and 73%, respectively). When these three indices were combined, sensitivity and specificity were as follows. 1) If one of them is met, sensitivity and specificity is 84% and 53%. 2) If two of them are met, sensitivity and specificity is 52% and 86%. 3) If all of them are met, sensitivity and specificity is 33% and 96%. The prerenal azotemia group with FENa less than 1% showed significant change in FEUa(from 8.3±5 to 16.7±4.8, P=0.001) and FEUn(from 17.4±15 to 38.1±18, P=0.002) after restoration of volume depletion. Conclusion: FEUa and FEUn were significantly lower in PR than in ATN patients. If two of three indices are met, sensitivity for PR increased from 48% to 52%. FEUa and FEUn were significantly influenced by saline infusion, so it is necessary to ascertain that saline infusion had been initiated previously.

Effect of cats’ grooming behavior on apparent digestibility in domestic cats

김희성 서울대학교 대학원 2017 국내석사

The Ministry of Agriculture, Food and Rural Affairs (MAFRA) announced that the number of domestic cat households in 2015 was increased by 63.7% compared to 2012, according to a national survey of public awareness about animal care. This result suggested that the negative perception of cats was reduced and the behavior of independent cats was in harmony with modern life patterns. Cats are engaging in paw licking and face washing as well as licking the pelage in their normal life. A cat can spend approximately 25% to 30% of its time on grooming (Hart, 1976b; Panaman, 1981). Some cats have been observed to spend up to one-third of their awake time for grooming (Loureiro et al., 2014). Daily hygiene routine of grooming in cats results in the formation of hairballs, or trichobezoars when the animals are licked and ingested their own hair (Loureiro et al., 2014). Cats can generally get rid themselves of this problem by retching until the hairball is vomited. This experiment was conducted to evaluate the time budget and organization of grooming both in short-haired and long-haired cats. And the other purpose of this experiment was to assess the effect of grooming behavior of cats on apparent digestibility in domestic cats (Felis catus) by comparing the apparent digestibility of domestic cats using hair-included-feces and hair-removed-feces. A total of 10 adult domestic cats, average 4.3±0.89 kg body weight and average 3.5±1.38 year, were used for behavioral observation. There was no significant difference between long-haired cats and short-haired cats in behavioral time budget and organization of grooming. A total of 14 adult domestic cats, average 4.5±1.21 kg body weight and average 3.3±1.38 year, were used for nutrient digestibility trial. The treatments of digestibility trial were HI; hair-included-digestibility and HR; hair-removed- digestibility. The apparent nutrient digestibility using hair-removed-feces was higher than hair-included-feces. Therefore, the digestibility of dry matter, crude protein, crude ash, ADF and NDF has been underestimated approximately 6%, 7%, 15%, 12% and 10%, respectively when calculated using conventional digestibility method for domestic cats. Because of the chemical composition of hair included in feces, the nutrient digestibility using hair-removed-feces was higher than that of hair- included-feces. The nutrient digestibility between long-haired and short-haired cats had no difference when it was calculated with hair-included-feces. However digestibility of NDF and amino acid in long-haired cats showed higher than that of short-haired cats approximately 4-8%. Therefore, this experiment demonstrated that the presence of hair in the fecal samples should be considered before calculating the apparent nutrient digestibility of domestic cats (Felis catus).

Area Reduction of Bio Signal Processor for Implantable Cardioverter Defibrillator

김희성 성균관대학교 일반대학원 2009 국내석사

Recently observing the population statistics, the number of people over sixty ages becomes larger. Due to this aging society, the heart disease patients also increase rapidly. So the ICD (Implantable Cardioverter-Defibrillator) has been intensively studied to alleviate the heart disease. In conventional ICDs, In this paper, we develope Bio-Signal Processor for Implantable Cardioverter Defibrillator (ICD), which detects arrhythmia and classifies therapies, based on atrium and ventricular signal information from the heart. We propose methods to find accurate information at the Peak Detection part, and detect the episode without huge size of buffers. In result, we solve the problem, which may occur wrong information at the peak sensing detect, and reduce the total number of gates about 30% on previous system 최근의 인구 통계를 살펴보면, 60세 이상의 인구가 전체 인구에서 차지하는 비율은 점차 증가하고 있다. 인구 고령화 사회로의 진입이 가속화 될수록 심장질환의 환자 역시 증가 할 것이다. 따라서 체내에 이식하여 심장의 부정맥을 판단하고 치료할 수 있는 이식형 제세동기의 수요 역시 증가할 것이다. 본 논문에서는 심실의 신호와 심방의 신호를 통해서 부정맥을 판단하고, 치료신호를 보낼 수 있는 Bio Signal Processor의 면적을 감소시키기 위한 방법을 제안한다. 심방과 심실신호의 최곳값을 찾기 위해 peak sensing의 시작 지점과 신호의 최곳값이 발생한 지점의 차이만큼 지연 전달하는 방법을 통해 별도의 버퍼를 사용하지 않도록 설계하였다. 또한 부정맥을 판별하기 위한 심실과 심방의 정보를 논리연산을 통한 비트 값만을 저장하는 방법으로 버퍼의 사용을 줄였다. 그 결과 기존면적의 70%만을 사용하면서 동일한 수행을 할 수 있도록 설계하였음을 보인다.

주거환경개선사업의 커뮤니티 재생 효과에 관한 연구 : 종로구 창신동 일대 주거환경개선사업지구를 중심으로

김희성 서울대학교 환경대학원 2003 국내석사

Carbodiimide합성과 경화제로의 응용

김희성 성균관대학교 일반대학원 2010 국내석사

종래의 PSR(photo solder resist) 방식이 아닌 열경화성 레지스트를 이용하고 자외선노광과 현상을 통해 SR을 open시켜주는 방식 대신에 laser를 이용하여 이를 대신하는 방법에 대해서 연구이다. 이 방식은 종래의 PSR process를 훨씬 단축시킬 수 있을 뿐만 아니라 신뢰성 향상 및 고밀도화에 따른 미세한 SR registration 대응을 가능하게 할 수 있다. 금번 연구를 통해 고 분해능 주제인 에폭시로 bispehnol-A, 경화제로 phenol novolac(PN)을 사용하였고, 촉매로 TPP(triphenyl phosphine)를 사용한 연구결과와 경화제로서 Carbodiimide를 첨가 할 때의 거동을 비교하였다. 기판위에 상기 레진들을 도포 후에 열 경화 후 laser에 의한 가공성을 평가하는 것이 실행하여 Soler Resist로서 역할을 수행하는지를 알아보았다. 따라서 본 연구에서는 실제적인 사양을 충족하는 LDA (laser direct ablation)공법에 적합한 열경화성 레진의 응용으로서 가능성을 알아보았다. A study on the alternative for using laser instead of UV irradiation in the process of SR thermosetting-resist was done. This laser method has the capability of reducing process steps. The possibility of detailed SR characteristics as high density with reproducibility was tested. Carbodiimide macromonomers were synthesized with diisocyanate. And the structure was conformed with instrumental analyses such as IR, 13C-NMR, TGA etc. The average molecular weight was obtained as 2,000~6,000 by GPC. The formulation for LDA test was done with a resin of bisphenol-A type epoxy as binder, phenol novolac and carbodiimide as crosslinking agents, and TPP as a catalyst. After curing the crosslinked coatings on CCL irradiated by CO2 laser to evaluate the processability as a SR was evaluated. The possibility of the synthesized crosslinking agent for using as a SR with LDA process was investigated. In this study, a new crosslinking agent was introduced as a SR formulation successfully.

중학교 2학년 영어교과서용 씨디롬 교재의 언어기능별 학습활동과 멀티미디어 기능 유형 분석

김희성 충북대학교 교육대학원 2007 국내석사

The purpose of this study is to analyze the English-textbook CD-ROM titles for the 2nd-year middle school and make suggestions of better CD-ROM titles for English education in middle school. To conduct this study, five CD-ROM titles are selected and 2 sets of criteria are constructed: 1)learning activities according to language skills, 2)multimedia types. The results of the study are as follows. First, the five English-textbook CD-ROM titles have similar types and percentages of learning activities in terms of languages skills. Reading skills have remarkably high percentages of all kinds of language skill areas. Second, the multimedia analysis were divided into performing activities and checking answers and results. The multimedia types are classified into three types: the clicking type, the direct writing type, and the draging type. The clicking types are remarkably often presented in all five CD-ROM titles. It can be concluded that, first, when developing new text-book CD-ROMs, a variety of learning activities should be included and effective combination of language skills is strongly recommended, which is for students' interests, motivation and cooperation. For teachers, these will be necessary to improve students' participation and to raise students' confidence for English learning. Finally, the multimedia types have to be designed for efficient English language learning. The multimedia of various types provide motivating and maintaining students' interests and learning need.

한국기독교 사회운동에 대한 사회선교적 고찰 : 1920년대를 중심으로

김희성 崇實大學校 2002 국내석사