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연구논문 : 해안 및 내륙도시 내 토지이용도별 미세먼지 분포 특성 및 상호관련성에 관한 연구
한승욱 ( Seung Wook Han ),이순환 ( Soon Hwan Lee ),이화운 ( Hwa Woon Lee ) 한국환경과학회 2015 한국환경과학회지 Vol.24 No.11
In order to clarify the characteristics of PM10 in coastal and inland cities and their variation statistical analysis were carried out using environmental and meteorological data observed at Busan and Daegu metropolitans during 4 year from 2010. Averaged PM10 concentration was higher in industrial area than any other land-use sites, and its maximum value reach on over 50 ㎍/㎥ at Jangrim site in Busan. Temporal and spatial variations of PM10 concentration in Busan were more sharply, since topograph and mesoscale wind pattern in Busan is more complicated than those in Daegu. Correlation of PM10 concentrations between sites within Daegu appeared strongly and maximum values R2 is about 0.8. This indicate that because wind pattern induced by mesoscale forcing in Daegu are well unified, the variation of PM10 concentration tends to be similar in all sites within Daegu. However, due to complicate wind pattern induced by topography and coastal line, PM10 correlation of sites within Busan was weaker in comparison with in Daegu. And correlation of PM10 at same lane-use in Busan and Daegu tend to be related to the intensity of meteorological forcing, which can decide the intensity of wind pattern.
한승욱 ( Seung Wook Han ),최낙삼 ( Nak Sam Choi ),이민수 ( Min Soo Lee ),안흥근 ( Hung Kun Ahn ) 한국복합재료학회 2011 Composites research Vol.24 No.2
에폭시 수지와 유리섬유직물 간의 젖음성을 분석하였다. 에폭시 수지와 산무수물 경화제의 혼합비는 당량비 1:0.5, 1:1, 1:1.2로 하였고, 촉매는 혼합된 수지의 0.1wt%로 첨가하였다. DSC 경화거동분석 결과 이 혼합 수지는 상온에서 함침이 가능하였다. 혼합 수지에 대해 유리평판에 놓여진 유리섬유직물 위에 수지 한 액적(방울)을 투하 후 시간에 따른 접촉각 변화를 측정하였다. 또한, 일정량의 에폭시 수지 액적을 투하시켜 시간에 따른 젖음면적 변화를 측정하였다. 접촉각, 액적높이, 순수 젖음면적, 젖음계수를 측정함으로써 유리섬유직물에 대한 에폭시 수지의 젖음성을 비교 평가하였다. 그 결과 당량비 1:1.2에서 유리섬유직물에 대한 젖음성이 가장 우수하였다. Analysis of wettability between epoxy resin and glass fabric was studied. The mixing ratios of epoxy resin and anhydride hardener were varied as 1:0.5, 1:1 and 1:1.2. Catalyst content was fixed as 0.1wt% of the mixed resin. A curing analysis by differential scanning calorimeter(DSC) showed a possible impregnation of the mixed resin at the room temperature. An effective contact angle of the mixed epoxy resin drop onto the glass fabric being preset on a flat glass plate was measured as a function of time. The wet area of the epoxy resin drop was also measured. Behaviors of the contact angle, the droplet height, the neat wet area and the coefficient of wettability were used to evaluate the wettability of the epoxy resin onto the glass fabric. It was concluded that the equivalent ratio of 1:1.2 was the most suitable for the wettability.
한승욱(Seung Wook Han),곽승범(Seung Bum Kwak),최낙삼(Nak Sam Choi) 대한기계학회 2014 大韓機械學會論文集A Vol.38 No.5
내연기관의 냉각기 고무호스에 사용되는 EPDM 고무는 열과 기계적 하중을 받는 동시에 국부적으로 형성된 전기적 스트레스를 받아 복합적인 노화가 발생한다. 본 연구에서는 EPDM 고무의 전기화학적 복합노화 시험을 하고, 아레니우스 관계식을 이용하여 노화온도(60℃, 80℃, 100℃)에 따른 가속수명 예측식을 구하였다. 수명에 영향을 미치는 인장변형률(5%, 10%)을 반영하여 예측식의 기울기(Ea/R) 및 아레니우스 상수(C)를 고려한 수정된 수명예측 식을 제안하였다. 이를 통해 노화온도와 인장변형률에 영향을 받은 EPDM 고무의 수명을 예측하였고, 수정된 수명예측 시간이 실제 실험결과의 편차 범위 이내에서 일치함을 확인하였다. The EPDM(ethylene-propylene diene monomer) rubbers used for manufacturing engine radiator hoses can be degraded by locally generated electrical stress in addition to thermal and mechanical stresses. This study presents an accelerated life prediction of the EPDM rubber under electrochemical stresses using the Arrhenius formula under various aging temperatures(60℃, 80℃, and 100℃). The modified life prediction formula considers the relationship between the gradient(Ea/R) and the Arrhenius constant(C). The effects of tensile strain(5%, 10%) on the life of these rubbers were investigated. The aging temperature influences EPDM rubber life, and tensile strain was predicted. It was confirmed that the modified life prediction was within the data deviation level of the test.
(Bi, Sb)₂ (Te, Se)₃계 박막의 열전 특성 및 온도 센서로의 응용
한승욱(Seung-Wook Han),김일호(Il-Ho Kim),이동희(Dong-Hi Lee) 한국진공학회(ASCT) 1997 Applied Science and Convergence Technology Vol.6 No.1
순간 증착법으로 Bi_(0.5)Sb_(1.5)Te₃ (p형)와 Bi₂Te₂.₄Se_(0.6) (n형) 박막을 제조하여 두께와 어닐링 조건에 따른 Seebeck 계수, 전기전도도, carrier 농도 및 이동도, 열전도도, 성능지수의 변화 등 열-전기적 특성을 조사하였다. 473K 에서, 1시간 진공 열처리한 결과 p형과 n형의 성능지수는 각각 1.3×10^(-3) K^(-1) 및 0.3×10^(-2) K^(-1)으로 향상되었으며 두께에 크게 의존하지 않았다. 이런 성질을 갖는 열전 박막을 소자화한 박막 온도 센서를 유리와 Teflon 기판 위에 제조하였으며, 이들의 온도 변화에 대한 열기전력, 민감도 및 시간 상수 등 센서 특성을 측정하였다. p및 n형의 leg 폭 1 ㎜×길이 16 ㎜인 박막 온도 센서의 경우, Teflon 기판일 때 좋은 성능을 나타내었으며, 민감도는 2.91 V/W, 시간 상수는 28.2초이었다. P-type (Bi_(0.5)Sb_(1.5)Te₃) and n-type (Bi₂Te₂.₄Se_(0.6)) thermoelectric thin films were deposited on glass and Teflon substrates by the flash evaporation technique. The changes in thermoelectric properties, such as Seebeck coefficient, electrical conductivity, carrier concentration, carrier mobility, thermal conductivity, and figure of merit, were investigated as a function of film thickness and annealing condition. Figures of merit of the thin films annealed at 473K for 1 hour were improved to be 1.3×10^(-3) K^(-1) for p-type and 0.3×10^(-3) K^(-1) for n-type, and they were almost independent of film thickness. Temperature sensors were fabricated from the thin films having the above mentioned properties. And thermo-emf, sensitivity, and time constant of the sensors were measured to evaluate their characteristics for temperature sensors. Thin film sensors deposited on Teflon substrates showed better performance than those on glass substrates, and their sensitivity and time constant were 2.91 V/W and 28.2 sec respectively for the sensor of leg width 1 ㎜ × length 16 ㎜.
한승욱(Seung-Wook Han),명노준(No-Jun Myung),최낙삼(Nak-Sam Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
The paper presents an overview of the present state of study on fatigue strength at very high number of cycles (N<SUB>f</SUB> > 10?). A classification of materials with typical S? N curves and influencing factors like notches, residual stresses and environment are given. The microstructural inhomogeneities and statistical conditions play an important role. Some informations for fatigue design of components are recommended.
EPDM 고무의 전기화학적 복합노화에 따른 조직변화 거동
한승욱(Seung-Wook Han),최낙삼(Nak-Sam Choi) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.11
Coolant rubber hoses used for the engine can be degraded and failed due to the effects of locally formed electricity under thermal stresses. This paper investigates ageing behaviors of carbon-black filled EPDM(ethylene propylene diene monomer) rubbers used as an engine radiator hose material. Experiments were performed in thermal loadings(60℃, 80℃, 100℃) under constant electro-static voltage(12V) and in electro-static voltages(0V, 12V) under constant thermal loading(100℃) at rubber specimens. Many micro-hole networks were formed in the skin layer under the electricity and high temperature. Through the microscopic analysis, the micro-hole networks could be confirmed resulting from the micro-break of carbon black phase and the scission of sulphoxide cross-links of the rubber phase.
한승욱(Seung-Wook Han),곽승범(Seung-Bum Kwak),최낙삼(Nak-Sam Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
EPDM rubber hoses under electricity effect, thermal and mechanical loadings can be degraded and failed. In this study, for carbon black filled EPDM(ethylene-propylene diene monomer) rubber used as a radiator hose material the electro-chemical degradation combined with mechanical and thermal loadings was analyzed. The tensile strains, voltage and temperature condition as a function of aging time was investigated.