Kapitza 열저항이 존재하는 나노복합재의 열전도 특성 예측을 위한 순차적 멀티스케일 균질화 해석기법에 관한 연구

신현성,양승화,유수영,장성민,조맹효,Shin, Hyunseong,Yang, Seunghwa,Yu, Suyoung,Chang, Seongmin,Cho, Maenghyo 한국전산구조공학회 2012 한국전산구조공학회논문집 Vol.25 No.4

본 연구에서는 분자동역학 전산모사와 유한요소해석 기반의 균질화 기법을 통해 나노복합재의 열전도 특성을 정확하고 효율적으로 예측할 수 있는 순차적 멀티스케일 균질화 해석기법을 제안하였다. 나노입자의 크기효과가 나노복합재의 유효 열전도 특성에 미치는 영향을 조사하기 위해 크기가 다른 구형 나노입자가 첨가된 나노복합재의 열전도 계수를 분자동역학 전산모사를 통해 예측했고, 그 결과 나노입자의 크기가 작아질수록 계면에서의 Kapitza열저항에 의해 나노복합재의 열전도 계수가 점차 감소하는 것으로 나타났다. 이러한 나노입자의 크기효과를 균질화 해석모델을 통해 정확하게 묘사하기 위해 Kapitza 열저항에 의한 계면에서의 온도 불연속 구간과 고분자 기지가 높은 밀도를 가지며 흡착되는 유효계면을 추가적인 상으로 도입하여 나노복합재를 입자, Kapitza 계면, 유효계면, 기지로 구성된 4상의 연속체 구조로 모델링하였다. 이후 순차적 멀티스케일 균질화 해석기법을 통해 유효계면의 열전도 계수를 나노복합재의 열전도 계수로부터 역으로 예측했으며, 이를 입자의 반경에 대한 함수로 근사하였다. 근사 함수를 토대로 다양한 입자 체적분율과 반경에 대한 나노복합재의 유효 열전도 특성을 예측하였으며, 유효계면에 대한 매개변수 연구를 수행하였다. In this study, a sequential multiscale homogenization method to characterize the effective thermal conductivity of nano particulate polymer nanocomposites is proposed through a molecular dynamics(MD) simulations and a finite element-based homogenization method. The thermal conductivity of the nanocomposites embedding different-sized nanoparticles at a fixed volume fraction of 5.8% are obtained from MD simulations. Due to the Kapitza thermal resistance, the thermal conductivity of the nanocomposites decreases as the size of the embedded nanoparticle decreases. In order to describe the nanoparticle size effect using the homogenization method with accuracy, the Kapitza interface in which the temperature discontinuity condition appears and the effective interphase zone formed by highly densified matrix polymer are modeled as independent phases that constitutes the nanocomposites microstructure, thus, the overall nanocomposites domain is modeled as a four-phase structure consists of the nanoparticle, Kapitza interface, effective interphase, and polymer matrix. The thermal conductivity of the effective interphase is inversely predicted from the thermal conductivity of the nanocomposites through the multiscale homogenization method, then, exponentially fitted to a function of the particle radius. Using the multiscale homogenization method, the thermal conductivities of the nanocomposites at various particle radii and volume fractions are obtained, and parametric studies are conducted to examine the effect of the effective interphase on the overall thermal conductivity of the nanocomposites.

에폭시/PES 복합소재의 인성 향상을 위한 멀티스케일 해석

신현성(Hyunseong Shin),한진규(Jin-Gyu Han),김병조(Byungjo Kim),이만영(Man Young Lee),박종규(Jong Kyoo Park),조맹효(Maenghyo Cho) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Epoxy resins are widely used as phase materials of matrix in fiber-reinforced composites. To overcome brittleness of cross-linked epoxy, thermoplastic modified epoxy has been extensively studied. However, specific toughening mechanism of thermoplastic modified epoxy has not been established in molecular viewpoint. Allegedly, toughening mechanisms of particle debonding, plastic yielding of nanovoids, and localized shear banding are primary origin of fracture toughness enhancement. The purpose of this study is to investigate the contribution of each toughening mechanism. In this study, PES is used as a toughening agent for the cross-linked epoxy composed of TGAP and DDS. Cohesive interface is also considered as it can affect toughening mechanisms. As a result, methodology of construction of finite element PES/epoxy model with cohesive interface is proposed.

경량 항공기 날개 FBG센서 잡음제거기법 연구

신현성(Hyunsung Shin),홍교영(Gyoyoung Hong) 항공우주시스템공학회 2018 항공우주시스템공학회 학술대회 발표집 Vol.2018 No.11

문제의 정보공간 분석을 통한 문제구조의 이해 및 학교수학에서의 그 활용

신현성 ( H . S . Shin ) 한국수학교육학회 1987 수학교육 Vol.26 No.1

Shigella spp. 의 연차적 추이에 관한 조사연구

신현성(Hyun-Sung Shin),오시환(Shi-Hwan Oh) 大韓微生物學會 1987 大韓微生物學會誌 Vol.22 No.4

한국인탕뇨병(韓國人糖尿炳)에 관(關)한 역학적(疫學的) 조사(調査) (충남대전지방당뇨병환자(忠南大田地方糖尿病患者)를 중심(中心)으로)

신현성 ( Hyun Sung Shin ),김상보 ( Sang Bo Kim ) 대한임상검사과학회 1979 대한임상검사과학회지(KJCLS) Vol.11 No.1

One hundred and five cases of diabetes mellitus patients adn1itted to C University hospital and S hospital from January 1968 to November 1968 had been studied and the following results were obtained. 1. Of the 105 cases; 67 cases were male patients and 38 cases were female patients; the sex ratio was 1.8:1. The age of the onset showed, 35.296 were under 40 years of age, 27.6% were under 50 years of age, 16.196 were under 30 years of age, 10.4% ·were under 20 years of age, 8. 6% were under 60 years of age and 1. 9% were under 70 years of age. 2. Sex and age distribution of first occurreance revealed; 41.9% were under 40 years of age, 22.8% were under 50 years of age, 15.2% were under 30 years of age, 10.5% were under 20 years of age, 3.8% were under 60 years of age. 3. Obese patients (over 10% of ideal body weight) were 44.7% of diabetes mellitus. 4. 18.1% showed certain family linkage. 5. Distribution of ABO blood group in diabetic patients were; group owere 45.8%,. patients. Group A were 33.3%, group B were 15.2%, and group AB were 5.9%. 6. The common symptoms were weakness (81.9%), thirst (73.3%), polyuria (65.7%),. etc. 7. The complications were vascular complications (68.6%), inefction (43.7%), retionpathy (16.2%), albuminuria (15.2%) and neuropathy (15.2%). 8. In most cases, the control of diabetes was inadequate and diet control by the patients was also very poor even after the concrete diagnosis made. 9. In general, quantity and quality of the hospital meal were considered as satisfactorily (30.5%), unsatisfactorily (65.7%) and excessively (3.8%). 4, 5, 6, 7, of the patients had treated thanselves during the first year before the hospitel care 16.296 in 2~3 years, 13.3% in 4~6 years 3.8% in 7~9 years 0.6% in 10~13 years, 3.8% over 14 year and 16.2% were incertain.

고속철 제동장치 브레이크 허브의 계측장비개발

신현성(Hyun-Sung Shin) 산업기술교육훈련학회 2009 산업기술연구논문지 (JITR) Vol.14 No.3

Hwa Young, one of the professional companies manufacturing large materials, has strived to localize the break hub which is one of the main parts of KTX, and hoped to develop the exclusive measuring machine to assure its quality itself. Fortunately, automatic measuring machine which is essential for quality assurance was developed through the academic-industrial cooperation between the company and Korea Polytechnic College to solve the bottleneck in production. As a result the company comes to have the equipment to be capable of manufacturing the break hub domestically

비행시험을 위한 SBAS수신기 간섭 요구사항 분석

신현성 ( Hyun-sung Shin ),홍교영 ( Gyo-young Hong ),한지애 ( Ji Ae Han ),홍운기 ( Woon Ki Hong ) 한국항행학회 2017 韓國航行學會論文誌 Vol.21 No.6

최근 항공교통량이 폭발적으로 증가됨에 따라 항공로 수용력 증대를 위한 다양한 연구가 진행되고 있다. 기존 VOR/DME장비를 기준으로 설정된 항공로 상 분리간격의 한계를 보완하기 위하여 인공위성을 활용하는 GNSS가 고려되고 있다. 또한 GNSS 오차를 보정할 수 있는 시스템인 SBAS를 이용하여 더욱 더 정확한 위치정보를 얻으려 노력하고 있다. ICAO에서는 2025년까지 SBAS 도입을 권고하고 있고 우리나라 또한 2014년부터 한국형 SBAS인 KASS개발에 착수하였다. 이에 KASS 개발에 따른 노력으로, 적절한 수신기 설계가 요구되어 본 논문에서는 측정항목에 대한 간섭임계값 및 위성 수신 안테나의 앙각에 따른 수신 안테나 이득을 분석하였다. Recently, as the air traffic volume has been explosively increased, various studies are being conducted to increase the air passenger capacity. In order to compensate the limitation of the separation distance on the aerodrome established on the basis of existing VOR / DME equipment, GNSS utilizing satellite is considered. In addition, we are trying to obtain more precise location information by using SBAS, a system that can correct GNSS error. ICAO recommends introducing SBAS until 2025, and Korea has also started to develop KASS, a Korean SBAS since 2014. Therefore, in this paper, we analyze the interference threshold for the measurement items and the receiving antenna gain according to the elevation angle of the satellite receiving antenna.

충남 금산 지역주민에서 B형한염 표면항체 (HBsAb) 발현빈도에 관한 연구

신현성 ( Hyun Sung Shin ),셔희숙 ( Hee Suck Shu ),이민웅 ( Min Woong Lee ) 대한임상검사과학회 1993 대한임상검사과학회지(KJCLS) Vol.25 No.1

The authors have investigated the frequencies of serum HBsAb positives among the 2,836 inhabitants of Gumsan- Gun ChungcheongnamDo who participated in the epidemiological study from April 26, 1985 to May 31, 1986. The results were summerized as following. HBsAb marker detection rate against male was 25.7%(342/1,329), 21.4%(322/1,507) in female and 23.4% ( 664/2,836) in all. The areas shown the highest HBsAb positive rate were: Gumseong- Myun 41.0% in male, Gums-eong -Myun 28.6% in female, and GumseongMyun 36.5% in all. The range of frequency of HBsAb positive was 15.7%~41.0% in male 8.8%~28.6% in female and 15.2%~36.5% in all. The age groups shown the highest HBsAb positive rate were : 50~59 age group 41.4% in male, 40~49 age group 30.8% in female and 50~59 age group 33.3% in all. The range of frequency in the age groups was 0%~33.3% in all. The prevalence rates of HBsAb by occupation were: People who work in the fields of professional, technicians and relates : 66.7% (8/12), agriculture, animal husbandary, foresting, marine products industry and hunting : 38.9% (7 /18), administrative officials and government officials : 34.9% (95/272). Service Job : 28.1% (262/931) primary school pupile: 13.4%(27/202) middle school pupile 15. 1% ( 48/318), highschool pupile 16.3% (64/392), pregnancy women: 20.1 %(64/244).

대전시 얼부 주민의 귀에서 분려된 진균의 벤도조사

신현성 ( Hyun Sung Shin ) 대한임상검사과학회 1999 대한임상검사과학회지(KJCLS) Vol.31 No.2

The author have investigated the frequencies of fungi from externa1 auditory ear among the 153 inhabitants of Taejon on city who participated in the epidemiological study from July 3, 1996 to July 20, 1996. The resu1ts were summerized as following. In order of frequency of fungi isolated from ears cu1ture were Penicillium spp. (24.8%), Aspergllus spp. (20.2%) and Cladosporium spp. (18.3%). The age groups shown the highest positive fungi rate were 50% for those 40-49 years old and next 47.4 % in the 50-59 age. The range of fungi isolated from age groups in a11 were 10.2%-50%. In both sides of the ears, the right side showed 4 1. 9% whi1e the left side showed 29.1 %. Age distribution of fungi isolated from both ears shown the highest positive rate were 62.5% in 50-59 age group for left side of ear, 52.9% in 20-29 age group for right side and 50.0% in 40-49 age group for both sides. According to ABO blood groups the preva1ent rate of fungi showed the highest ηpe in both sexes but a lower rate in 0 and B group respectly.