• 한국기계가공학회지
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• 제2권2호
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• pp.14-21
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• 2003

Rapid prototyping(RP) has been used for design verification and proto sample or mold manufacturing. Many RP systems have been introduced into the market during the past 15 years. However, until now, the systems have used mainly for external physical models (mono function), and have the basic but critical limitation of one material on one stage (mono material). To overcome the limitations of mono-material and mono-function of conventional. RP systems, the concept of Functional Phototype Development (FPD) is newly proposed in this paper FPD provides the necessary prototype functions such as mechanical, optical, chemical and electrical properties in order to meet the broad requirements of the industry. The paper illustrates the representative achievements of electronic components such as the multi-layer printed circuit board(MLB). Experimental results demonstrate that FPD has great potential applied to broad industrial uses and that It Will be a powerful tool in the neat future.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.817-824
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• 2014

To ensure the safety of research reactors, the water level must be maintained above the required height. When a pipe ruptures, the siphon phenomenon causes continuous loss of coolant until the hydraulic head is removed. To protect the reactor core from this kind of accident, a siphon breaker has been suggested as a passive safety device. This study mainly focused on two variables: the size of the pipe rupture and the timing of air entrainment. In this study, the size of the pipe rupture was increased to the guillotine break case. There was a region in which a larger pipe rupture did not need a larger siphon breaker, and the water flow rate was related to the size of the pipe rupture and affected the residual water quantity. The timing of air entrainment was predicted to influence residual water level. However, the residual water level was not affected by the timing of air entrainment. The experimental cases, which showed the characteristic of partical sweep-out mode in the separation of siphon breaking phenomenon [2], showed almost same trend of physical properties.

• Journal of the Korean Wood Science and Technology
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• 제22권2호
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• pp.54-60
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• 1994

The pine bark from mechanical pulp industry was cooked with bisulfite liquor, and the chemical and physical properties of the spent liquor after cooking for 90 minutes, which allowed partial defibration were determined. Lignosulfonate or lignin-related materials in the spent liquor have a molecular weight of approximately 3,000, which is lower than that of commercial lignosulfonate (C-LS) prepared from wood. The sulfonic equivalent weight calculated by colloid titration was 307 for C-LS, 238~239 for spent liquor. The contents of lignosulfonic acid and phenolic hydroxyl groups on $C_9$ unit of lignin in the spent liquor were 0.98~0.99, and 1.51~1.66, respectively. These values were remarkably higher than those of C-LS. Especially the content of phenolic hydroxyl group was almost twice that of C-LS. The viscosity of spent liquor after freeze drying was very low compared to C-LS. The dispersing ability of spent liquor was almost equivalent to or more than that of C-LS.

• 대한기계학회논문집B
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• 제30권7호
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• pp.682-691
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• 2006

This study was conducted to assess the effect of mixed fuel composition and mass fraction on spray inner structure in evaporating transient spray under the various ambient conditions. Spray structure and spatial distribution of liquid phase concentration are investigated using a thin laser sheet illumination technique on the multi-component mixed fuels. A pulsed Ar+ laser was used as a light source. The experiments were conducted in a constant volume vessel with optical access. Fuel was injected into the vessel with electronically controlled common rail injector. Used fuel contain $i-octane(C_8H_{18}),\;n-dodecane(C_{12}H_{26})$ and $n-hexadecane(C_{16}H_{34})$ that are selected as low-, middle- and high-boiling point fuel, respectively. Experimental conditions are 25Mpa, 42MPa, 72MPa and 112MPa in injection pressure, $5kg/m^3,\;15kg/m^3\;and\;20kg/m^3$ in ambient gas density, 400K, 500K, 600K and 700K in ambient gas temperature, 300K and 368K in fuel temperature, and different fuel mass fraction. Experimental results indicate that the more high-boiling point component, the longer the liquid phase it were closely related to fuel physical properties, but injection pressure had no effect on. And there was a high correlation between the liquid phase length and boiling temperature at 75% distillation point.

• 한국수소및신에너지학회논문집
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• 제34권1호
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• pp.59-68
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• 2023

In this study, the performance of high-pressure fuel pumps was compared to find a high-pressure pump suitable for dimethyl ether (DME) fuel, and to establish a database of basic data on flow rates. The use of DME in compression ignition engines can reduce pollutant emissions. The cetane value of DME is higher than that of diesel fuel. The physical properties of DME are similar to liquefied gasoline gas (LPG), and when pressurized at a pressure of 6 bar or more, it changes from gas to liquid. Two types of high pressure pumps used in this study were independent injection type pump and a wobble plate type pump. Two high-pressure pumps with different injection types were compared. By measuring and comparing the performance changes of the two high-pressure pumps, a pump suitable for DME was selected and performance improvement measures were proposed. The changed experimental conditions to measure the performance change of the high pressure pump were increased in the units of 100 to 1,000 rpm and 100 rpm, and the experiment was performed at common rail pressures 300 and 400 bar. it was confirmed that the DME inside the fuel supply system remained in a liquid state through temperature sensors, pressure sensors, and pressure gauges. As a result of the experiment, it was confirmed that the flow rate discharged from the high-pressure fuel pump increased as the motor rotational speed increased, and the flow rate of the high-pressure fuel pump

• 한국의류산업학회지
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• 제7권4호
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• pp.445-451
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• 2005

Up to the present, fabric finishing methods have been mainly employed for the application of chitosan. However, the coated chitosan acid salt is prone to be detached from the fabric during the laundering process. In order to improve the wash fastness, chitosan treated fabrics are being subjected to thermal curing. In this study, chemical crosslinking reaction by epichlorohydrin was introduced to improve the problem of the thermal curing. An improvement of the wash fastness is expected since the coated chitosan component on the fabric become insoluble by the introduction of the crosslinking. The demerit of the single chitosan treatment (inferior handle due to the excessive stiffness, etc.) was supplemented by the application of chitosan-polyurethane mixture solution. The mixture ratios were adjusted to 1 : 0, 1 : 0.25, 1 : 0.5, 1 : 1, and 1 : 2 for the chitosan/PU mixture. Physical and mechanical properties of the finished fabric specimens were measured using the Kawabata Evaluation System(KES), and hand values were calculated accordingly based on the translational formulas.

• 콘크리트학회논문집
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• 제13권6호
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• pp.575-583
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• 2001

본 연구는 폐콘크리트에서 발생되는 재생골재를 구조용 콘크리트 골재로서의 활용방안을 제시하기 위한 것으로서, 보통콘크리트보다 취약한 강도 개선을 목적으로 압축강도는 300kgf/$\textrm{cm}^2$ 이상의 재생골재 콘크리트를 제조하고 보통콘크리트와 물리적특성을 비교하였다. 연구결과, 일반적으로 재생골재 혼입률이 증가함에 따라 압축강도, 인장강도 등 역학적 성능이 저하하는 것으로 나타났으나, 단위시멘트량과 배합수 그리고 실리카퓸 등 적절한 혼화재료의 사용을 통해 300~600kgf/$\textrm{cm}^2$ 범위의 압축강도를 갖는 콘크리트의 제조가 가능하였다. 그러나 구조용으로 사용가능한 재생골재 콘크리트를 제조.활용하기 위해서는 장기적인 내구성능 등에 대한 지속적인 연구가 필요하다.

• Tribology and Lubricants
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• 제30권3호
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• pp.156-167
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• 2014

This paper presents the test results of small dipstick-gage-type engine-oil-deterioration-detection sensor. The measured sensor signal characteristics for the capacitance and temperature are analyzed. The engine oil deterioration condition correlates with the electrical property of the dielectric constant that comprised with physical properties such as TAN (Total Acid Number), TBN (Total Base Number) and viscosity. Several problems encontered during the test of the sensor system are improved. The results of vehicle tests show that the capacitance signal is stable after the engine stops. Therefore, the sensor should start measuring the parameters for monitoring the engine oil condition after the engine stops. The engine is considered to be in a stopped state if the difference between the maximum and minimum values of the oil capacitance measured every 1 min is below 0.02 pF. The key test results in this paper will help in the development of an engine oil change warning algorithm.

• Tribology and Lubricants
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• 제30권3호
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• pp.168-176
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• 2014

This paper presents an engine oil change warning algorithm based on the test results of a small dip-stick-gage-type engine-oil-deterioration-detection sensor, software to realize the algorithm and a display device to apply the software. The algorithm determines the engine oil deterioration condition from the rate of change in the dielectric constant based on the average measured capacitance at $80^{\circ}C$ after the engine stops. The rate of change in the dielectric constant at the time for oil change correlates with the time that one of recommended warning limits for engine oil physical properties such as TAN (Total Acid Number), TBN (Total Base Number) and viscosity is first reached. At this point, a warning signal for oil change appears on the display device like a smart-phone or individual display device. The frames of smartphone app have three stages. The user can directly input all of the thresholds into the frame of the smartphone app. The screen of the display device comprises one frame for each warning signature with the related message. The user can input the thresholds to the device through a USB cable connected to a personal computer.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.447-448
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• 2009

본 논문에서는 과산화수소($H_2O_2$) 분해 반응을 이용, 이산화망간($MnO_2$) 및 탄산수소나트륨($NaHCO_3$)을 촉매제로 사용하여 콘크리트 기포발생 유도를 극대화 하였다. 또한 기포콘크리트 초경량화를 이루기 위한 최적배합 도출 및 소요강도 확보 등의 다양한 실험을 통해 경량기포콘크리트의 물리적 역학적 특성을 알아보았다. 실험결과 전반적으로 KS F 4039 및 KS F 2459규정에 있는 품질기준에 충분히 만족하는 결과를 보였다.