• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.599-603
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• 2003

This paper present an error compensation system and On-Machine Measurement(OMM) system for improving the machining accuracy of ultra-precision lathe. The Fast-Tool-Servo(FTS) driven by a piezoelectric actuator is applied for error compensation system. The controller is implemented on the 32bit DSP for feedback control of piezoelectric actuator. The control system is designed to compensates three kinds of machining errors such as the straightness error of X-axis slide, the thermal growth error of the spindle. and the squareness between spindle and X-axis slide. OMM is preposed to measure the finished profile of workpiece on the machine-tool using capacitive sensor with highly accurate ruby tip probe guided by air bearing. The data acquisition system is linked to the CNC controller to get the position of each axis in real-time. Through the experiments, it is founded that the thermal growth of spindle and tile squareness error between spindle and X-axis slide influenced to machining error more than straightness error of X-axis slide in small travel length. These errors were simulated as a sinusoidal signal which has very low frequency and the FTS could compensate the signal less than 30 m. The implemented OMM system has been tested by measuring flat surface of 50 mm diameter and shows measurement error less than 400 mm

• Fire Science and Engineering
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• v.11 no.1
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• pp.3-9
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• 1997

The objective of this research is to study on the formations of thermal stratification in a room in case of several furniture fires such as trashcan, carpet, sofa, mattress and wardrobe as a fire starter in a residential room by performing the experimental studies. The uniformly distributed fire in case of carpet showed that the ignition and the initial growth period were relatively short while the fully developed period was considerably long. The concentrated fires such as the mattress and wardrobe showed that the ignitions and the initial growth periods were relatively long. When fire spread to only direction, like the case for the trashcan with a regular shape, there was one peak of temperature profile, and for the irregular shaped furniture such as chair, sofa, mattress and wardrobe, there were two or more peaks. The interface heights for the furniture fires were around 1[m] maintaining constant state. However, at the time of the maximum temperature, the interface height was lowered to 0.25[m]-0.75[m] from the floor.

• Fire Science and Engineering
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• v.26 no.2
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• pp.53-58
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• 2012

In this study fire control characteristics for inflammable materials of water curtain system are experimentally analyzed. Heat release rate for pinewood and gasoline was calculated using Room Corner Tester (RCT) and fire test apparatus for water curtain system is manufactured. Nozzles (180 degree of injection angle, 8.2 mm of orifice diameter) are installed at the nearby ceiling of place at 5 m distance from fire originate and temperature profile as well as transmission are obtained from the fire experiment of pinewood and gasoline in the water curtain system. Based on the results, parameters of engineering importance for fire control characteristics of water curtain system such as generation of high temperature smoke and thermal phenomena of fluid flow by injection nozzle are identified.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.22-26
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• 1983

P+N and P+NN+ solar cells with the area of 3.36 $\textrm{cm}^2$ were fabricated by thermal diffusion. Under the light intensity of 100 mW/$\textrm{cm}^2$, total area(active area) conversion efficiency was 13.4%(14.7%) for P+N cell fabricated by 15 min boron predeposition at 94$0^{\circ}C$ and 20 min annealing at 80$0^{\circ}C$, and 14.3%(15.6%) for P+NN+ cell processed by 15 min boron predeposition at 94$0^{\circ}C$ and 50 min annealing at 80$0^{\circ}C$ after 20 min back phosphorus diffusion at 1,05$0^{\circ}C$. The minority carrier lifetime in bulk of P+NN+ cells was increased about 2~3 times comparing with P+N cells because of guttering and BSF effect due to back phosphorus doping. The methods used for efficiency improvement were AR coating, Ag electroplating, back doping and fine grid pattern as well as the control of front doping profile.

• Journal of the Korean Vacuum Society
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• v.14 no.3
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• pp.147-152
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• 2005

The structural evolution of $Ni(400\;\AA)/Au(400\;\AA)$ films on p-type GaN during thermal oxidation in ai. was investigated by in situ x-ray scattering experiments. These results indicate that Ni layer and Au layer intermix during thermal oxidation. Au-rich solid solutions containing the different amount of Ni atoms are formed during oxidation. The Ni atoms in Au-rich solid solution out-diffuse as the oxidation proceeds resulting in the formation of NiO(111) phase. Despite of the complete oxidation at $650^{\circ}C$, the position of bulk Au(111) diffraction profile indicates that small amount of Wi atoms are still incorporated in the Au phase.

• Current Photovoltaic Research
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• v.3 no.3
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• pp.80-84
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• 2015

We suggest new emitter formation method using solid-phase epitaxy (SPE); solid-phase epitaxy emitter (SEE). This method expect simplification and cost reduction of process compared with furnace process (POCl3 or BBr3). The solid-phase epitaxy emitter (SEE) deposited a-Si:H layer by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) on substrate (c-Si), then thin layer growth solid-phase epitaxy (SPE) using rapid thermal process (RTP). This is possible in various emitter profile formation through dopant gas ($PH_3$) control at deposited a-Si:H layer. We fabricated solar cell to apply solid-phase epitaxy emitter (SEE). Its performance have an effect on crystallinity of phase transition layer (a-Si to c-Si). We confirmed crystallinity of this with a-Si:H layer thickness and annealing temperature by using raman spectroscopy, spectroscopic ellipsometry and transmission electron microscope. The crystallinity is excellent as the thickness of a-Si layer is thin (~50 nm) and annealing temperature is high (<$900^{\circ}C$). We fabricated a 16.7% solid-phase epitaxy emitter (SEE) cell. We anticipate its performance improvement applying thin tunnel oxide (<2nm).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.198-201
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• 2002

In this paper, the dependence of Ni-silicide properties such as sheet resistance and cross-sectional profile on the dopants have been characterized. There was little dependence of sheet resistance on the used dopants such as As, P, $BF_{2}$ and $B_{11}$ just after RTP (Rapid Thermal Process). However, the silicide properties showed strong dependence on the dopants when thermal treatment was applied after formation of Ni-silicide. $BF_{2}$ implanted sample shows the best stable property, while $B_{11}$ implanted one was thermally unstable. The main reason of the excellent property of $BF_{2}$ sample is believed to be the retardation of Ni diffusion by the flourine.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.8
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• pp.80-90
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• 1994

The ultra shallow junction was formed by 2-step RTP. Phosphorus solid source(P$_{2}O_{5}$) was transfered on wafer surface during RTG(Rapid Thermal Glass Transfer) of which process condition was 80$0^{\circ}C$ and 60sec. The process temperature and time of the RTD(Rapid Thermal Diffusion) were 950~105$0^{\circ}C$ during 5~15sec respectively sheet resistances were measured as 175~320$\Omega$/m and junction depth and dopth and dopant surface concentration were measured as 0.075~0.18$\mu$m and 5${\times}10^{19}cm^{4}$ respectively. Ti-silicide was formed by 2-step RTA after 300$\AA$ Titanium was deposited. The 1st RTA (2nd RTA) was carried out at the temperature of $600^{\circ}C$(700~80$0^{\circ}C$) for 30 seconds (10~60 seconds) under N$_2$ ambient. Sheet resistances after 2nd RTA were measured as 46~63$\Omega$/D. Si/Ti component ratio was evaulated as 1.6~1.9 from Auger depth profile. Ti-Silicided n-p junction diode (pattern size : 400$\times$400$\mu$m) was fabricated under the RTD(the process was carried out at the temperature of 100$0^{\circ}C$ for 10seconds) and 2nd RTA(theprocess was carried out at the temperature of 750$^{\circ}C$ for 60 seconds). Leakage current was measured 1.8${\times}10^{7}A/mm^{2}$ at 5V reverse voltage. Whent the RTD process condition is at the temperature of 100$0^{\circ}C$ for 10seconds and the 2nd RTA process condition is at the temperature of 75$0^{\circ}C$ for 60 seconds leakage current was 29.15${\times}10^{9}A$(at 5V).

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.166-177
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• 1993

A simplified thermal analysis method to evaluate the maximum temperature of the CANDU 37-element fuel bundle within a fuel basket in a given spent fuel dry storage canister has been presented along with the results of sample analyses performed to examine the parametric effects of the ambient conditions on the maximum fuel temperature within a canister. To solve the multi-dimensional heat transfer problem of the complex geometry of rod bundles within a canister where three modes of heat transfer are superimposed, the CANDU spent fuel bundles stored in the dry storage canister are first replaced by equivalent concentric fuel cylinders. The simplified axi-symmetric two-dimensional multi-mode heat transfer problem of the equivalent fuel cylinders is then analyzed with an existing computer code, HEATING5, using additional input data and heat transfer correlations. A comparison between the predicted temperature profile and the mock-up test results shows that the agreement is quite satisfactory.

• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.60-66
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• 2015

Conjugate heat transfer analysis was performed to investigate the flow and cooling performance of the high pressure turbine nozzle of gas turbine engine. The CHT code was verified by comparison between CFD results and experimental results of C3X vane. The combination of k-${\omega}$ based SST turbulence model and transition model was used to solve the flow and thermal field of the fluid zone and the material property of CMSX-4 was applied to the solid zone. The turbine nozzle has two internal cooling channels and each channel has a complex cooling configurations, such as the film cooling, jet impingement, pedestal and rib turbulator. The parabolic temperature profile was given to the inlet condition of the nozzle to simulate the combustor exit condition. The flow characteristics were analyzed by comparing with uncooled nozzle vane. The Mach number around the vane increased due to the increase of coolant mass flow flowed in the main flow passage. The maximum cooling effectiveness (91 %) at the vane surface is located in the middle of pressure side which is effected by the film cooling and the rib turbulrator. The region of the minimum cooling effectiveness (44.8 %) was positioned at the leading edge. And the results show that the TBC layer increases the average cooling effectiveness up to 18 %.