철-탄소 합금에서 r'- phase의 성장에 미치는 탄소의 영향

장충근,오헌진,오희필 충남대학교 자연과학연구소 1979 學術硏究誌 Vol.6 No.2

To obtain the diffusion coefficient of nitrogen in Fe-C alloys, the 0-3% C-Fe alloy was nitrided by the liquid drop nitriding method in the temperature range of 650 C- 850 C. The main results observed are: (1) The frequency factor Do of nitrogen in 0-3%C-Fe alloy; Do(mC) = 1.17 exp[-1.08(mC)]㎠/sec (2) The activation energy Q of nitrogen in the alloy; Q(mC)= 27.2 exp [30.7(mC)]Kcal/mole (3) And finally, the diffusion coefficient of nitrogen in 0-3%C-Fe alloy is D_(N)= Do(mC) exp[-Q(mC)/RT] ㎠/sec

원형톱에 의한 속성수 절단 소요 동력에 관한 연구

최윤성 ( Yun Sung Choi ),김대현 ( Dae Hyun Kim ),오재헌 ( Jae Heun Oh1 ) 한국임학회 2014 산림과학 공동학술대회 논문집 Vol.2014 No.-

본 연구에서는, 단벌기 바이오매스 생산림(Short rotation forest, SRF)에 식재되어 있는 속성수인 이태리포플러( Populus euramericana)을 이용하여 수확 시 소요되는 동력을 측정하여 수확기계동력원을 선정하기 위한 기초자료를 제공하기 위하여 수행되었다. 실험 수준은 밀기속도(0.41, 1.25,2.5 m/s) 3수준, 절단속도(800, 1,000, 1,200 rpm) 3수준, 직경(50, 70, 90, 110, 130 ㎜) 5수준으로 선정하였다. 실험결과, 밀기속도에 따른 최대토크는 0.41 m/s 일 때 30.4 N-m, 최소동력은 191.37 W로나타났다. 밀기속도 1.25 m/s 일 때 최대토크와 최소동력은 각각 30.1 N-m, 194.88 W, 2.5 m/s 일때 최대토크와 최소동력은 각각 31.9 N-m, 204.10 W로 나타났다. 또한 밀기속도 0.41 m/s 보다 2.5m/s 일 때 최대토크는 각각 4.8, 10, 7.2%, 최소동력은 6.8, 10, 11.8%가 증가하였으며, 밀기속도 0.41m/s 인 경우보다 6.8% 많은 동력을 필요로 하는 것으로 나타났다. 따라서, 실험결과를 바탕으로 측정된 소요 동력 기준으로 수확기계의 동력원을 선정할 수 있을 것으로 판단된다. In this study, Italy poplar( Populus euramericana) was selected for test specimen to measure cutting power when it harvested. Three levels of feed rate (0.41, 1.25, 2.5 m/s), three levels of sawing speed (800, 1,000, 1,200 rpm), and five levels of stem diameter (50, 70, 90, 110, 130 ㎜) were used as test variables. As results, the maximum torque, 30.4 N-m for feed rate 0.41 m/s, the minimum power, 191.37 W. The maximum torque and power, such as 30.1 N-m, 191.37 W for feed rate 1.25 m/s. The maximum torque and power, such as 31.9 N-m, 204.10 W for feed rate 2.5 m/s. Also, feed rate 0.41 m/s than feed rate 1.25 m/s, the maximum torque such as 4.8, 10, 7.2%, minimum power 6.8, 10, 11.8% increased. The feed rate 0.41 m/s than 6.7% many power to required. Using the results of this experiment as the base, The measured power source of the power requirements by the harvesting machine is determined to be able to select.

On the Sum Rules of Slater Integral and LS-Energy Matrix for the Long Range Central Interactions

Oh, Heun-Jin 충남대학교 대학원 1976 論文集 Vol.6 No.-

3차원의 조화진동자 파동함수를 기저벡타로 해서 핵자들 사이의 상호작용의 LS-에너지 행렬요소를 계산하는 방법이 Talmi, Thieberger등에 의해서 개발되었다. 본 논문에서는 이 계산의 결과를 검증하는 방법의 하나로서 원거리 극한 (Long Range Limit)의 경우에 대한 Talmi적분의 성질을 이용한 검산법을 연구하여 核子의 배치가 diagonal이냐 아니냐에 따라서 Slater 적분 F^(k) 및 LS-Energy Matrix <|H|>_(LS)의 계산식중에 나타나는 Talmi적분의 계수들의 합이 1혹은 0 이라는 두 合法則을 찾아냈다. 또 核子배치가 특별한 경우 예컨데 l_(1)=l_(1)´, l_(2)=l_(2)´인 경우에 대한 Racah계수의 합법칙 ◁이미지삽입▷ (원문을 참조하세요)을 이용해서 제3의 合法則 ◁이미지삽입▷ (원문을 참조하세요)을 얻었다. 이 검증법은 실제로 계산된 F^(k), <H>_(LS)에 적용되어 잘 맞음이 확인 되었다.

A Study on Tractive Resistance Prediction of Logging machine

Oh, Jae-Heun,Cha Du-Song 강원대학교 삼림과학연구소 2001 Journal of Forest Science Vol.17 No.-

본 연구는 지면끌기집재에 사용되는 기계에 의해 견인되는 견인목의 견인저항을 예측하기 위해 견인목의 중량, 견인저항계수, 지면의 경사 등의 함수로 표현된 수학적 모델들을 개발하였다. 또한 만능재료시험기와 토양조를 이용한 실험실조건에서 4개 수종(잣나무, 일본잎갈나무, 신갈나무, 굴참나무)의 견인저항계수를 산출하였다. 산출한 견인저항계수와 가상 조건을 이용하여 개발된 3가지의 수학적 견인저항 모델에 적용하였다. 그 결과 견인목 중량에 대한 견인저항력의 비(T/Wt)는 지면의 경사가 증가할수록 전형적으로 증가하였으며, 반지면끌기집재가 지면끌기집재보다 견인저항력이 더 작게 나타났다. 본 연구의 결과는 집재작업기계의 선정과 집재윈치의 동력요구량 산정엔 기본적인 자료로 활용할 수 있을 것이다. This study was conducted to predict the tractive resistance for tree length logs being skidded by ground based logging machine. The mathematical models for predicting the tractive resistance of tree length log have been developed. The tractive resistance is expressed as a function of log weight, skidding coefficient, and ground gradient. The skidding coefficients for four species of Korean pine, Japanese larch, mongolian oak, and cork oak were determined under laboratory condition using universal testing machine and small soil bin, Three different tractive resistance models were applied to four species and compared with each other. The ratios (T/Wt) of skidding-line tensions to the skidding log weight increased linearly with increment in ground gradient. Semi-ground skidding generally required smaller tensions than ground skidding under given condition. Results of this study can be utilized as basic information for logging machine selection and power requirement of skidding winch. Key words ; Tractive resistance, ground skidding, forest machine, logging machine, forest machanization

Fabrication of High-Sensitivity Skin-Attachable Temperature Sensors with Bioinspired Microstructured Adhesive

Oh, Ju Hyun,Hong, Soo Yeong,Park, Heun,Jin, Sang Woo,Jeong, Yu Ra,Oh, Seung Yun,Yun, Junyeong,Lee, Hanchan,Kim, Jung Wook,Ha, Jeong Sook American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.8

<P>In this study, we demonstrate the fabrication of a highly sensitive flexible temperature sensor with a bioinspired octopus-mimicking adhesive. A resistor-type temperature sensor consisting of a composite of poly(N-isopropylacrylamide) (pNI-PAM)-temperature sensitive hydrogel, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, and carbon nanotubes exhibits a very high thermal sensitivity of 2.6%.degrees C-1 between 25 and 40 degrees C so that the change in skin temperature of 0.5 degrees C can be accurately detected. At the same time, the polydimethylsiloxane adhesive layer of octopus-mimicking rim structure coated with pNIPAM is fabricated through the formation of a single mold by utilizing undercut phenomenon in photolithography. The fabricated sensor shows stable and reproducible detection of skin temperature under repeated attachment/detachment cycles onto skin without any skin irritation for a long time. This work suggests a high potential application of our skin-attachable temperature sensor to wearable devices for medical and health-care monitoring.</P>

Heat transfer characteristics in pulsating combustion : 펄스연소의 열전달특성에 관한 연구

Oh, Sang Heun 釜山大學校 工科大學 1983 工科大學 硏究 報告 Vol.26 No.-

Fuel Properties of Woody Pellets in Domestic Markets of Korea

Oh, Jae-Heun,Hwang, Jin-Sung,Cha, Du-Song Institute of Forest Science 2014 Journal of Forest Science Vol.30 No.4

This study investigated physical properties and combustion gas characteristics for 8 types of wood pellets (4 domestic and 4 imported products) distributed in the domestic market. Results showed that most pellet types were first-grade pellets in the wood pellet quality standards in Korea with the exception of 3 pellet types from K company (second-grade in mechanical durability), G company (off-grade in nitrogen content) and P company (second-grade in ash percentage). Mixed pellets which contained more lignin and sap content were higher in mechanical durability (%) than that of white pellets. From the combustion gas analysis results, NOx emitted from all pellets combustion was at acceptable levels for national emission standard of the Clean Air Conservation Act except for pellets from G company. In addition, CO levels from all types of wood pellets were acceptable except for pellets from D company and domestic pellets were higher CO levels than imported pellets. These results indicate the higher CO levels in domestic pellets due to the usage of forest thinning materials including logging debris which usually had the high content of bark.

Skin-Attachable, Stretchable Electrochemical Sweat Sensor for Glucose and pH Detection

Oh, Seung Yun,Hong, Soo Yeong,Jeong, Yu Ra,Yun, Junyeong,Park, Heun,Jin, Sang Woo,Lee, Geumbee,Oh, Ju Hyun,Lee, Hanchan,Lee, Sang-Soo,Ha, Jeong Sook American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.16

<P>As part of increased efforts to develop wearable healthcare devices for monitoring and managing physiological and metabolic information, stretchable electrochemical sweat sensors have been investigated. In this study, we report on the fabrication of a stretchable and skin-attachable electrochemical sensor for detecting glucose and pH in sweat. A patterned stretchable electrode was fabricated via layer-by-layer deposition of carbon nanotubes (CNTs) on top of patterned Au nanosheets (AuNS) prepared by filtration onto stretchable substrate. For the detection of glucose and pH, CoWO<SUB>4</SUB>/CNT and polyaniline/CNT nanocomposites were coated onto the CNT-AuNS electrodes, respectively. A reference electrode was prepared via chlorination of silver nanowires. Encapsulation of the stretchable sensor with sticky silbione led to a skin-attachable sweat sensor. Our sensor showed high performance with sensitivities of 10.89 μA mM<SUP>-1</SUP> cm<SUP>-2</SUP> and 71.44 mV pH<SUP>-1</SUP> for glucose and pH, respectively, with mechanical stability up to 30% stretching and air stability for 10 days. The sensor also showed good adhesion even to wet skin, allowing the detection of glucose and pH in sweat from running while being attached onto the skin. This work suggests the application of our stretchable and skin-attachable electrochemical sensor to health management as a high-performance healthcare wearable device.</P> [FIG OMISSION]</BR>

A Study on Dynamic Characteristics of Forestry Machine ( 2 ) - Characteristics of forest ground as sources of ride vibration in forestry vehicles -

(Jae Heun Oh),(Bum Jin Park),(Kazuhro Aruga),(Toshio Nitami),(Hiroshi Kobayashi),(Du Song Cha) 한국임학회 2002 한국임학회 정기학술발표논문집 Vol.2002 No.-

Dynamic simulation of rubber tracked mini-forwarder

( Jae Heun Oh ),( Kyoung Jin Shin ),( Du Song Cha ) 한국임학회 2004 한국임학회 학술발표논문집 Vol.2004 No.-