• 소성∙가공
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• 제6권5호
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• pp.435-445
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• 1997

In order to study the manufacturing possibility of connecting rod by direct quenching method, the difference between connecting rod by direct quenching and that by general heat treatment were investigated by observing microstructure, by measuring mechanical properties, by conducting fatigue testing, and by measuring the amount of tool wear in actual cutting. Connecting rod manufactured by direct quenching had better fatigue life than that by general heat treatment, which was due to homogeneous microstructure, and higher strength. The amount of cutting tool wear of connecting rod by direct quenching was higher than that by general heat treatment, which was due to low machinability and high toughness of tempered martensite microstructure. Therefore it will be added the study of heat treatment and cutting condition for manufacturing by direct quenching.

• 대한한의학회지
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• 제38권4호
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• pp.82-89
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• 2017

Objectives: We here do propose that cancer treatment moxibustion should be used both direct moxibustion and electro-moxibustion simultaneously. Methods: Electro-moxibustion is used in $38^{\circ}C$ low-heat level and it will help to raise parasympathetic and to bring stability of mentality. Direct moxibustion is used in rice size and will help to raise sympathetic and to induce visceral reflection and visceral motion. Results: Electro-moxibustion increased average body heat by $+2.51^{\circ}C$ and kept patients from suffering pains. Direct moxibustion increased average body heat by $+1.2^{\circ}C$ by meridian point-internal organs reflection. Conclusions: Both use of direct moxibustion and electro-moxibustion simultaneously will be superior to the only either direct moxibustion or electro-moxibustion for cancer treatment moxibustion.

• 임산에너지
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• 제21권3호
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• pp.10-17
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• 2002

본 연구는 단소용 대나무 악기재를 효과적으로 건조하기 위하여 열처리 및 몇 가지 스케줄에 의한 건조를 실시하였다. 평균 직경 2.2cm, 길이 60cm정도의 솜대를 이용하였다. 열처리 효과를 평가하기 위하여 무처리 및 열처리재로 구분하였으며 적당한 건조 조건 조사를 위해서 20℃, 65%와 40℃, 40% 그리고 대기상태의 3가지 조건으로 실시하였다. 탄화와 재색의 결함이 발생하지 않는 열처리의 최적 온도 조건은 180℃정도가 적당하였으며 열처리가 할렬의 수와 할렬 크기의 발생을 줄였으며 건조결함을 발생하지 않는 최적의 조건은 온도 20℃, 관계습도 65%이지만 건조를 할 때 기간이 너무 많이 소요되는 단점이 있기 때문에 40℃, 40%에서 건조시키는 것이 더욱 효율적이었다.

• 열처리공학회지
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• 제10권3호
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• pp.159-164
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• 1997

Non-alloyed and 1.0%Ni alloyed ductile cast iron were cast into the sand mold and metal mold, and finer graphite size was obtained in case of metal mold casting. Direct tempering after casting showed the slight increase of absorbed energy, which is largely due to the relieving of residual stress that is developed during casting. After austempering heat treatment, higher impact energy was obtained in case of metal mold casting than sand mold casting, which is due to the finer graphite size.

• 열처리공학회지
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• 제26권1호
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• pp.7-13
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• 2013

Vacuum heat treatment(indirect heating method) has long exposure time at high temperature and low quenching rate. Contrarily salt bath heat treatment (direct heating method) has short exposure time at high temperature and fast cooling rate. With these different features of processes, mechanical properties such as hardness, tensile strength and impact strength of products show very different results. In this study, Salt bath heat treated products showed higher tensile strength and impact strength than vacuum heat treated products but hardness was not much different. These lower mechanical properties of vacuum heat treated products are due to differences in heat process and secondary hardening with high temperature tempering process. Consequently, It indicates that salt bath heat treatment is better way than vacuum heat treatment for product to have high mechanical properties.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.431-434
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• 2008

In the present study, direct quenching of alloyed steel after hot forging was simulated using commercial finite element program, $FORGE^{TM}$. A typical heat treatment of alloyed steels consists of quenching for hard martensite and subsequent tempering for toughness. In the practice, forgings which cool down to room temperature are heated to temperature of austenite regime. As investigated in the present study, direct quenching of hot forged stock would be beneficial in terms of energy saving. This process has already been propose and termed as ausforging or forged hardening. However, it is well known that quenching temperature would be the most critical factor to control heat treated forging properties. And it is very difficult to control quenching temperature when forged stock gets directly quenched after forging. In this study, we have calculated final forging temperature of stock. Also, quenching simulation was conducted using a series of material parameter which were also calculated using JMATpro, a commercial program for physical properties of materials.

• Membrane and Water Treatment
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• 제10권5호
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• pp.387-394
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• 2019

Membrane distillation (MD) is one of the water treatment processes which involves the momentum, heat and mass transfer through channels and membrane. In this study, CFD modeling has been used to simulate the heat and mass transfer in the direct contact membrane distillation (DCMD). Also, the effect of operating parameters on the water flux is investigated. The result shows a good agreement with the experimental result. Results indicated that, while feed temperature is increasing in the feed side, water flux improves in the permeate side. Since higher velocity leads to the higher mixing and turbulence in the feed channel, water flux rises due to this increase in the feed velocity. Moreover, results revealed that temperature polarization coefficient is rising as flow rate (velocity) increases and it is decreasing while the feed temperature increases. Lastly, the thermal efficiency of direct contact membrane distillation is defined, and results confirm that thermal efficiency improves while feed temperature increases. Also, flow rate increment results in enhancement of thermal efficiency.

• 한국정밀공학회지
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• 제11권6호
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• pp.12-19
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• 1994

This paper deals with the bending fatigue strength of SNC815 carburized spur gears. The test gears are heat-treated by two different treatments. One is the direct quenching after car-burization. The other is treated by reheating and quenching. The fatigue test at a constant stress amplitude is performed by using an electrohydraulic servo-controlled pulsating tester. The S-N curves are obtained and illustrated. The fatigue strength of direct quenched gears is higher than that of reheated quenched gears. The fatigue strength is estimated from the hardness and the residual stress by using the experimental formula proposed by Tobe and Inoue. The estimated strength is close to the test results, and the validty of the formular is confirmed.

• 열처리공학회지
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• 제13권1호
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• pp.21-26
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• 2000

This study deals with effects of heat-treatment on the fatigue strength of SNC815 spur gears. The test gears are heat-treated by two different treatments. After carburization, one group of the test gears is quenched directly, while the other group is fumace cooled, reheated then quenched. The fatigue test at a constant stress amplitude is performed by using an electrohydraulic servo-controlled pulsating tester. The S-N curves are obtained and illustrated. By comparing the estimated strength with the experimental results, the validity of the previous experimental formula, presented by the author for estimating the fatigue strength of carburized gears, was discussed on these tested gears.

• 대한기계학회논문집B
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• 제23권3호
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• pp.330-341
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• 1999

An experimental study for the two types of burners used in the non-oxidizing direct fired furnaces of the heat treatment process for the cold rolled plate has been carried out to investigate the combustion characteristics and the oxidization of the surface of steel plate. A steep temperature gradient and entrainment of residual oxygen were found near the heating surface in the flame of the nozzle mixing burner which has strong swirl velocity component. It was concluded that the elimination of the residual oxygen and the increase of the temperature of combustion gas on the heating surface are needed to enhance the performance of the burners for application to the non-oxidizing direct fired furnaces.