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1wt.% Bi 함유 무연황동의 인장강도와 내식특성에 대한 연구
주영석 ( Y S Joo ),이상봉 ( S B Lee ),김시영 ( S Y Kim ),주창식 ( C S Joo ),정병호 ( B H Jung ) 한국열처리공학회 2011 熱處理工學會誌 Vol.24 No.3
This study has been investigated for tensile properties with lead-free brass containing 1wt.% of Bi. And also characteristic of corrosion resistance was analyzed by polarization test. An increase of tempering temperature was found to tend to decrease tensile strength, and percentage of elongation was shown to be the lowest value at 300°C. On the other hand, the elongation was increased with an increase of tempering temperature after 300°C. The change of mechanical properties was closely related with the content and shape of acicular Witmanst?tten α formed at the interface of β phase as well as in β phase. Tensile strength had a tendency to be decreased with an increase of test temperature. The elongation was shown to be the lowest value at around 300°C, while it began to increase as test temperature rose after 300°C. It might be speculated that the reason that elongation was decreased was found to form bismuth film at the interface of α/β phase leading to be easily brittle when loaded by tensile stress. The lead-free brass containing 1wt.% of Bi had similar characteristic of corrosion resistance with a free-cutting brass with 3.4wt.% of Pb in spite of higher fraction of β phase.
자율 무인 무인잠수정 OKPO-600의 개발과 실해역 성능 확인
주영석(Young Seok Joo),조경남(Kyung Nam Jo),김주일(Ju Il Kim),이광민(Kwang Min Lee),한성곤(Sung Gon Han),박명철(Myung Chul Park),유진수(Jin Su Ryu),우종식(Jong Sik Woo),한민구(Min Gu Han) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
This paper deals with autonomous underwater vehicle (AVY) named OKPO-600 which has been designed and manufactured by Daewoo Shipbuilding & Marine Engineering(DSME). OKPO-600 is implemented to be 2.6m in length, 0.28m in diameter and weight about 70㎏ in air. A test is conducted to verify the basic function of OKPO-600.
김기환,주영석,Kim, Ki-Hwan,Joo, Young-Serg 한국연초학회 1983 한국연초학회지 Vol.5 No.2
The tensile strength (Pm) . elongation percentage ($\varepsilon$) , elastic modulus (I) , and specific volume (Sv) were calculated from the data of tensile characteristics of By 104 .and Burley 21 tobacco leaves, which were measured over a relative humidity from 60 to 80% at $20\pm2^{\circ}C$.The important results obtained were as follows.(1) Tensile strength(Pm) The "Pm"of By 104 was greater than that of Burley at. The "Pm"in both varieties were increased toward the upper stalk position and according to the decrease of relative humidity. The "Pm" of parallel piece to tile vein in a leaf were greater than that of right angle piece to the vein. (2) Elongation percentage ($\varepsilon$). The "s" of By 104 was higher than that of Burley 21. The "s" in both varieties were increased toward the upper stalk position and according to the increase of relative humidity. The "s" of parallel Piece to the vein in a Burley leaf was greater than that of right angle piece to the vein. (3) Elastic modulus (E) The "E" of Burley 21 leaf was higher than that of By 104. The "E" in both varieties were increased toward the lower stalk position and according to decrease of relative humidity. The "E"of parallel piece to the vein in both varieties leaves were greater than that of right angle piece to tile vein. (4) Specific volume (Sv) The "Sv" of Burley 21 leaf was increased than that of By 104. The "Sv" in both varieties were increased toward the lower stalk position and according to the decrease of relative humidity.ot;Sv" in both varieties were increased toward the lower stalk position and according to the decrease of relative humidity.dity.
김기환,한정성,주영석,Kim, Gi-Hwan,Han, Jeong-Seong,Joo, Yeong-Seok 한국연초학회 1987 한국연초학회지 Vol.9 No.2
1. Under the current workroom conditions It is very difficult to control the moisture contents of raw materials in season of summer or winter. 2. The moisture absorption of the materials under the contributive conditions showed the efficiency of 65% in relative humidity and temperature of the currant workroom. 3, The results from this study, however , appeared the deviation of moisture content of the products by the order of 0.1% compared to the current deviation of 2.6~2.7%. 4. Equilibrium moisture contents of the tobacco was Inversely proportional to the temperature and directly related to the relative humidity of the workroom. 5. On the basis of the above results , the standard conditions of the workroom obtained from this study considering with the external temperature in winter could reduce energy by 17.4% through 38.4% .
Freon Gas흡착 및 열처리에 의한 담배조직의 물리적, 역학적 특성변화연구
김기환,유광근,주영석,Kim, Ki-Hwan,Yoo, Kwang-Kun,Joo, Young-Serg 한국연초학회 1984 한국연초학회지 Vol.6 No.1
In the tobacco industry, it is important to study the change of mechanical property occurring the expansion process. The purpose of this study is to attain basic data for development of a tobacco expansion method. 1 . Freon gas was adsorbed to tobacco under various conditions of temperature, relative humidity and pressure, and then the amount of freon gas adsorbed was analyzed by GC. Freon adsorption rate of Burley 21 was more than that of By104 at the same condition and about 17 $\pm$ 1% moisture content produced better adsorption rate. 2. Freon adsorbed sample were heated to about $150^{circ}C\;to\;230^{\circ}C$ in a drying oven and recycle duct form about 2 to 30 seconds, and then the change of mechanical property were measured. Heated leaf was damaged when the tissue was pressed by the force of above $0.5x10^8dyn/cm^2$. The optimum condition of no damage of the sample was below the temperature of 15$0^{\circ}C$ and heating time of 10 seconds. It was more economically advantages to treated sample in a recycle duct than to be in a drying oven. By this process, the specific volume of the heated sample was increased from 80 to 110 percent in comparison to that of untreated sample.
Total Lagrangian 기반 음해적 입자법을 이용한 외팔보 동적 거동 해석
이완기(Wan Ki Lee),주영석(Young Suk Joo),김진현(Jin Kim) 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.5
SPH(smoothed particle hydrodynamics)는 Lagrangian 기반 수치해석 기법이며 입자를 단위로 사용하는 무격자 방식이다. 기존 SPH 기법으로 구현된 구조해석은 두 가지 문제점을 가지고 있다. 대변형 지점에서 인장불안정으로 인한 입자 겹침 문제와 수치적 민감성으로 인하여 작은 해석간격을 사용하는 문제이다. 본 연구에서는 total Lagrangian 기반 SPH 기법으로 구조해석을 구현하여 인장불안정 문제를 해소한다. 그리고 동회전성 커널함수를 사용하고 탄성력 연산을 음해적으로 수행하여 보다 큰 해석간격을 사용하여도 해석이 발산하지 않도록 한다. 외팔보 동적 거동 해석을 수행하여 수치모델 정확성을 검증하고 구조해석 적용 가능성을 확인한다. Smoothed particle hydrodynamics (SPH) is a particle-based meshless Lagrangian numerical method. The status quo SPH-based structural analysis has two problems: overlapping particles at large deformation points owing to tensile instability and marginal limits on the time-step size owing to the inherent numerical sensitivity. In this study, a total Lagrangian SPH method is employed in the structural analysis to solve the tensile instability problem. In addition, simulation divergence is prevented even when a relatively larger time-step is used by performing a numerical analysis implicitly and using a corotated kernel function. Dynamic analyses of cantilever beams are performed to verify the accuracy of the numerical model presented in this study and its applicability to structure analysis.
한옥진(Ok-Jin Han),주영석(Young-Seok Joo),한흥국(Heung-Kuk Han) 산업기술교육훈련학회 2007 산업기술연구논문지 (JITR) Vol.12 No.1
The snow melting system by electric heating wires which is adopted in this research is a part of road facilities to keep surface temperature of the road higher than freezing point of water for melting the snow accumulated on it. The system is designed to increase traffic safety and capacity. The electric heating wires are buried under paved road at a certain depth and operated automatically and manually. Design theory, amount of heating, and installation standard vary according to economic situation, weather condition, and installation place and purpose of each country which is applying the system. We tried to figure out the appropriate range of required heat capacity and installation depth and intervals for solving snowdrifts and freezing problems with the minimum electric power consumption. The most important factors of designing the system are calculation of heating capacity depends on weather condition and depth and interval of the electric heating wires depend on air condition respectively. We performed this research under the air temperatures(-2℃, -5℃, -8℃) , the intervals of the electric heating wires(70mm, 100mm, 125mm), and installation depths(50mm, 70mm, 100mm). The results of this research were verified by a program Fluent.
권중기 (J. K. Kwon ),주영석 (Y. S. Joo ),김시영 (S. Y. Kim ) 한국동력기계공학회 2008 한국동력기계공학회 학술대회 논문집 Vol.2008 No.11
The Mono flex impeller(CR), which is installed inside the bronze housing of the conventional Mono flex pump, is causes the abrasion. Because of the source of breakdown, there is a need to study to prevent the abrasion. In this study, to solve this problem, abrasion test of the rotating impeller equipped with poly-acetal membrane bushing shape between the mono flex housing and impeller were conducted using several approaches. Through the change of oil temperature, rotation speed of the impeller and propulsion pressure, the abrasion test equipped with CR-rubber and actual bushing was intended to contribute to the actual design of the parts by conducting experimental comparison and analysing.
진의봉(U. B. Jin),주영석(Y. S. Joo),김시영(S. Y. Kim) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The scale correction was analyzed for model to prototype with roughness effects in the pipe. The flow law of log and law of the wall were used by theoretical analysis to calculate the scale correction with surface roughness effects. For the surface roughness in the pipe flow for marine pipe fittings in boiler, heat exchange and the velocity field in the turbulent boundary layer on the wall is determined by scale for law of log and law of the wall. In this study, the calculation for the variation of diameter for roughness effects with variation velocity was investigated to design the facility of the ship. It was shown that the surface roughness effects in scale effects for model to prototype relation could be applied depending on scale ratio in model to prototype.