• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2013년도 추계 학술논문 발표대회
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• pp.23-25
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• 2013

In this study, the results are compared with the case of the concrete with embedded heating wire to verify the performance of the IB made in order to improve the workability and affordability, and to determine the effectiveness of early frost damage prevention. The IB was made using the 5W heating wire and layed on the upper surface of the concrete. The temperature was reduced to below 0℃ approximately within 24 hours, then approached the external temperature thereafter. On the other hand, when the 20W heating wire was used to make the IB and applied the same way, the temperature remained around -2 to 3℃ on the average even through the temperature was reduced to below 0℃, due to the heating wire with relatively large heating capacity. It appeared to reach 85% of the direct heating by embedding the heating wire relatively deeper in the concrete. However, it was determined that using the IB made with the 20W heating wire will prevent the early frost damage to some degree in -10℃.

• Journal of Welding and Joining
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• 제25권4호
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• pp.28-34
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• 2007

The heating unit of direct heating method manufactured as the plasma spray coating of $TiO_2/NiCr$ conductive heating material on the surface of heating unit in order to improve the disadvantages of indirect heating method. $TiO_2$ and NiCr (80wt.%Ni-20wt.%Cr) that had the properties of conduction and heating was chosen for the conductive heating material. The compositions of the composite powders were studied $TiO_2-30wt.%NiCr\;and\;TiO_2-10wt.%NiCr$. As the heating temperature was increased, the hardness of heating layer was increased because of the fine microstructure and the decrease of porosity. The adhesion strength was decreased for coarsening and connection of voids in the insulation layer, and the electrical resistivity of heating layer was increased for fine crack formation and growth. In this study, the best efficient sprayed coatings with heating unit was concluded as the plasma sprayed $TiO_2-10wt.%NiCr$ coatings that was heat treated at $300^{\circ}C$.

• 대한공업교육학회지
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• 제32권2호
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• pp.188-198
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• 2007

이 연구의 목적은 열처리 방법으로 탄소나노튜브에 백금나노 입자를 담지하는 것이다. 이 목적을 달성하기 위해서 염화백금산 수용액으로부터 hexachloro platinate(IV)를 탄소나노튜브에 흡착시킨 후 환원제를 사용하지 않고 질소분위기에서 $400^{\circ}C$로 열처리 하여 백금 나노입자를 담지 시켰다. 탄소나노튜브에 흡착된 hexachloro platinate(IV)의 함량은 UV-visible spectrophotometer를 사용하여 정량하였고, 탄소나노튜브에 담지된 백금 나노입자 존재와 분산을 확인하기 위해서 열중량분석, X-ray 회절분석, 투과전자현미경 관찰을 수행하였다. hexachloro platinate(IV)를 흡착시킨 탄소나노튜브를 환원제를 사용하지 않고 질소분위기에서 $400^{\circ}C$에서 열처리하면 2 nm 이하의 백금 나노입자가 균일하게 분포되었다. 한편, $800^{\circ}C$에서 열처리한 경우에는 백금입자들이 상호 응집현상이 발생하여 백금 입자의 크기가 커지고 분산이 균일하지 못했다. 따라서 hexachloro platinate(IV)를 탄소나노튜브에 흡착시킨 후 질소분위기에서 $400^{\circ}C$의 간단한 열처리를 통해서 백금 나노입자를 담지시킬 수 있었다.

• 산업기술연구
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• 제24권A호
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• pp.17-22
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• 2004

In the study, we have developed a straightening system for 304 micro wires that are normally used in the medical and semi-conductor fields. To apply heat to the micro wires, we introduced the direct wire heating method which generates the thermal energy by the electrical resistance of the wire itself. To avoid the deterioration of the wire surface by the environment, such as the oxidation or the hydration, the $N_2$ gas was filled in the glass pipe in which the straightening process was being performed. A precision tension meter was also attached to control the tension of the wire during the heating and straightening process. In order to control the straightening process, several experimental investigations with varying the tension, the feeding velocity and the temperature (current) was carried out. As a result of experiments, we obtained the optimal processing conditions satisfying the straightness requirement of the micro wires.

• 대한기계학회논문집B
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• 제28권11호
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• pp.1289-1301
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• 2004

Direct numerical simulation (DNS) of strongly-heated air flows moving upward in a vertical tube has been conducted to investigate the effect of gas property variations on turbulence modification. Three heating conditions(q$_1$$^{+}$=0.0045, 0.0035 and 0.0018) are selected to reflect the experiment of Shehata and McEligot (1998) at the inlet bulk Reynolds numbers of 4300 and 6000. At these conditions, the flow inside the heated tube remains turbululent or undergoes a transition to subturbulent or laminarizing flow. Consequently, a significant impairment of heat transfer occurs due to the reduction of flow turbulence. The predictions of integral parameters and mean profiles such as velocity and temperature distributions are in excellent agreement with the experiment. The computed turbulence data indicate that a reduction of flow turbulence occurs mainly due to strong flow acceleration effects for strongly-heated internal gas flows. Thus, buoyancy influences are secondary but not negligible especially for turbulent flow at low heating condition. Digital flow visualization also shows that vortical structures rapidly decay as the heating increases.s.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.175-180
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• 2005

In this study, we have developed a novel wire straightener which uses the direct heating method (DHM) fer straightening the micro wire. Also, we have developed a shearing device for cutting the micro wire. In order to avoid the surface oxidization, we supplied the inert gas(Ar) during the heating process and examined the effect of gas flow rate. The effects of the tension and the current applied to the tungsten micro wires were also thoroughly studied. From various experiments and analyses, we could obtain fine straightness $(\approx1\;{\mu}m/1000\;{\mu}m)$ and roundness $(<{\pm}2{\mu}m\;/100{\mu}m)$ when the tension is $500\~~600gf$ and the current is about 1.5A. for burrfree cutting, counter-punch method which two cutters moving contrary was used. The cutting blade has various U-groove angle where upper $10^{\circ}$, $mid:25^{\circ}$, lower $0^{\circ}$. After the shearing process, we confirmed the shearing section.

• 한국레이저가공학회지
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• 제10권2호
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• pp.5-15
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• 2007

A new printing process for LCD color filter is proposed in this work by using the localized laser heating, which is called laser-induced spray printing (LISP) process. The LISP is a non-contact process, which injects the ink from the donor substrate to the glass substrate by the bubble pressure induced by laser heating. The temperature distribution of the donor substrate is calculated numerically to explain the ink ejection phenomena. The composition of the ink was includes the red pigment, n-butanol, xylene, BCA and epoxy. Experiments were conducted by using the fiber laser system, and the color filter patterns were deposited successfully under the proper laser heating conditions.

• 산업기술연구
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• 제25권B호
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• pp.121-126
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• 2005

Micro wires manufactured by the straightening process are used in the BT(Bio-Technology), IT(Information-Technology), NT(Nano-Technology). We have developed a novel wire straightener which uses the direct heating method(DHM) for straightening the micro wire and shearing device for burr-less cutting. In this study, we confirm the tendency of micro wire after the shearing process. It is impossible to remove the burr in the shearing process. However, the embodiment of minimum burr size after the shearing process is the best in-process method. In order to minimize the burr size, we have accomplished the various experiment condition such as the U-groove, the effect of the counter punch, the shear angle, clearance.

• 태양에너지
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• 제20권3호
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• pp.51-60
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• 2000

This paper deals with the design, construction and operation of a direct solar hot water heating system developed to harness the solar energy more effectively. The system introduced here uses a unique network of riser tubes and header pipes apart from the existing concept to exploit the physical properties of water which expands when it freezes. It also employs a special pressure relief mechanism for the header to prevent its breakage due to freezing. A number of tests are made to assure its functional reliability during frigid weather conditions and its superior performance over indirect systems.

• 패션비즈니스
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• 제19권4호
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• pp.92-108
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• 2015

This study aimed at developing a down jacket prototype that utilized sunlight as an alternative energy source with no air pollution. The jacket is filled with flexible solar panels and has a heat-generating function and LED function. In this study, three smart down jacket prototypes were developed, and the jacket's capabilities were demonstrated through the thermal effect on the performance test. The typical output voltage of the flexible solar panels was 6.4V. By connecting the 2 solar cell modules in series, the final output voltage was 12.8V. A battery charge regulator module was used the KA 7809 (TO-220) of 9V. Three heating pads were to be inserted into the belly of the jacket as direct thermal heating elements, and the LED module was configured, separated by a flash and an indicator. The smart down jacket was designed to prevent damage to the down pack without the individual devices' interfering with the human body's motion. Because this study provides insulation from extreme cold with a purpose, the jacket was tested for heat insulation properties of non-heating, heating on the back, heating on the abdomen, and heating on both the back and abdomen in a sitting posture in a static state. Thermal property analysis results from examining the average skin temperature, core temperature, and the temperature and humidity within clothing showed, that placing a heating element in one place was more effective than distributing the heating elements in different locations. Heating on the back was the most effective for maintaining optimal skin temperature, core temperature, and humidity, whereas heating on the abdomen was not effective for maintaining optimal skin temperature, core temperature, or humidity within clothing because of the gap between the jacket and the body.