• Journal of the Korean Vacuum Society
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• v.6 no.4
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• pp.308-313
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• 1997

TDS (Thermal Lkso~ption Spectroscopy)system, for diagnosis of CRT manufacturing process, was designed and constructed. Outgassings and themla1 desorptions from the part or materials of CRT can be measured and analysed with this system at various temperatures. The system is consisted of 3 pirrts. vacuum chamher and pumping system with variable conductance, sample heating stages & their controller, and outgassing measurement devices, like as ion gauge or quadrupole mass spectrometer. The ultimate pressure of the system was under $1\times10^{-7}$ Pa. With the variable conductance system, the effective pumping speed of the chamber could he controlled from sub 11s to 100 11s. The effective pumping speed values were determined by dynamic flow measurement principle. The temperatures and ramp rate of sample were controlled by tungsten heater and PID controller up to $600^{\circ}C$ within t $\pm 1^{\circ}C$$difference to setting value. Ion gauge & QMS were calibrated for quantitative measurements. Some examples of TDS measurement data ;ind application on the CRT process analysis were shown.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.64-70
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• 2008

Temperatures of engine head and liner depend on many factors such as spray and combustion process, coolant passage flow and engine related structures. To estimate the temperature distribution of engine structure, multi-dimensional computational fluid dynamics (CFD) codes have been mainly adopted. In this case, it is of great importance to obtain the realistic wall temperature distribution of entire engine structure. In the present work, a CFD-FEM coupling methodology was presented to address this demand. This approach was applied to a real large-size marine diesel engine. CFD combustion and coolant flow simulations were coupled to FEM temperature analysis. Wall heat flux and wall temperature data were interfaced between combustion simulation and solid component temperature analysis via translator by a commercial CFD package named FIRE by AVL. Heat transfer coefficient and surface temperature data were exchanged and mapped between coolant flow simulation and FEM temperature analysis. Results indicate that there exists the optimum cell thickness near combustion chamber wall to reasonably predict the wall heat flux during combustion period. The present study also shows that the effect of cell refining on predicting in-cylinder pressure during combustion is negligible. Hence, the basic guidance on obtaining the wall heat flux needed for the reasonable CFD-FEM coupling analysis has been established. It is expected that this coupling methodology is a robust tool for practical engine design and can be applied to further assessment of the temperature distribution of other engine components.

• Applied Chemistry for Engineering
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• v.8 no.1
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• pp.1-7
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• 1997

We show that the usage of the cyclic pressure function in the freeze drying is more effective than the drying rate of the constant pressure process. The ultimate object of this process is to reduce energy costs by shortening the drying time. In this work, the concept of cyclic pressure function to decrease the drying time and the effects of the following factors on drying rate are considered ; pulse type, size in amplitude of pressure, size of intermediate time. Temperature for drying has always been maintained constantly at $20^{\circ}C$ and the pulse type could have found to give useful results than the constant pressure by altering chamber pressure from low pressure to high pressure Also, when the amplitude of the pulse is 0.4 torr and the intermediate time is six hour the drying rate was increased considerably.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.552-561
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• 2018

Biomass, a carbon-neutral resource, is an alternative energy source for exhaustion of fossil fuel and environmental problems. Most of energy production systems using biomass operate with a thermal chemical conversion method. Amongst them, gasification generates syngas and applies to boilers or engines for the production of heat and electricity. However, Tar could be formed during the production of syngas and it is condensed at low temperature which may cause to clog the pipelines and combustion chamber, ultimately resulting in decrease of process efficiency. Thus this work utilized water and oily materials such as soybean oil, waste cooking oil and mineral oil for scrubbing liquid. The removal efficiency of Tar appeared 97%, 70%, 63% and 30% for soybean oil, waste cooking oil, mineral oil and water respectively.

• Journal of Biosystems Engineering
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• v.39 no.4
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• pp.330-335
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• 2014

Purpose: This study was conducted for enhancing the performance of a conventional quick freezer by introducing the supercooling state, using a low-temperature coolant. Methods: In the present investigation, the supercooling process was executed prior to quick freezing for reducing the time by which the temperature passes the zone of maximum ice crystal formation. Every food has different nucleation points and hence, we used silicone oil as the coolant for supercooling for easy modification of temperature. Additionally, for quick freezing, we used liquid nitrogen spray. Results: Using the heat exchanger-type precooler with silicone oil, the temperature of the chamber was easily changed for enabling supercooling. Particularly, the results of the freezing test with garlic indicated that this system improved the hardness of garlic after it was thawed, compared to the conventional freezing method. Conclusions: Before quick freezing, if the food item is subjected to the supercooling state, the time from nucleation to the temperature reaching the frozen state ($-5^{\circ}C$, which is the maximum ice crystal formation zone) will be shorter than that incurred using quick freezing alone. The combination of the heat exchanger-type supercooler and liquid nitrogen sprayer is expected to serve as a promising technology for improving the physicochemical qualities of frozen foods.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.10
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• pp.37-44
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• 1999

This paper report the implementation results of Monte Carlo numerical calculation for ion distributions in plasma dry etching chamber and of the surface evolution simulator using cell removal method for topographical evolution of the surface exposed to etching ion. The energy and angular distributions of ion across the plasma sheath were calculated by MC(Monte Carlo) algorithm. High performance MPP(Massively Parallel Processing) algorithm developed in this paper enables efficient parallel and distributed simulation with an efficiency of more than 95% and speedup of 16 with 16 processors. Parallelization of surface evolution simulator based on cell removal method reduces simulation time dramatically to 15 minutes and increases capability of simulation required enormous memory size of 600Mb.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.203-206
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• 2004

For the realization of PRAM, $Ge_2Sb_2Te_5$ (GST) has been employed for the phase transition between the crystal and amorphous states by electrical joule heating. Although there has been a vast amount of results concerning the GST in material aspect for the laser-induced optical storage disc applications, the process-related issues of GST for the PRAM applications have not been reported. In this work, the etching behaviors of GST were investigated when the processing conditions were varied in the high-density helicon plasma. The etching parameters of RF main power, RF bias power, and chamber pressure were fixed at 600 W, 150 W, and 5 mTorr, respectively. For the etching processes, gas mixtures of $Ar/Cl_2$, $Ar/CF_4$, and $Ar/CHF_3$ were employed, in which the etching rates and etching selectivities of GST thin film in given gas mixtures were evaluated. From obtained results, it is found that we can arbitrarily design the etching process according to given cell structures and material combinations for PRAM cell fabrications.

• Journal of Sensor Science and Technology
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• v.29 no.1
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• pp.27-32
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• 2020

This study proposes a pixel-patterning method for organic light-emitting diodes (OLEDs) based on thermal transfer. An infrared lamp was introduced as a heat source, and glass type donor element, which absorbs infrared and generates heat and then transfers the organic layer to the substrate, was designed to selectively sublimate the organic material. A 200 nm-thick layer of molybdenum (Mo) was used as the lightto-heat conversion (LTHC) layer, and a 300 nm-thick layer of patterned silicon dioxide (SiO₂), featuring a low heat-transfer coefficient, was formed on top of the LTHC layer to selectively block heat transfer. To prevent the thermal oxidation and diffusion of the LTHC material, a 100 nm-thick layer of silicon nitride (SiN_x) was coated on the material. The fabricated donor glass exhibited appropriate temperature-increment property until 249 ℃, which is enough to evaporate the organic materials. The alpha-step thickness profiler and X-ray reflection (XRR) analysis revealed that the thickness of the transferred film decreased with increase in film density. In the patterning test, we achieved a 100 ㎛-long line and dot pattern with a high transfer accuracy and a mean deviation of ± 4.49 ㎛. By using the thermal-transfer process, we also fabricated a red phosphorescent device to confirm that the emissive layer was transferred well without the separation of the host and the dopant owing to a difference in their evaporation temperatures. Consequently, its efficiency suffered a minor decline owing to the oxidation of the material caused by the poor vacuum pressure of the process chamber; however, it exhibited an identical color property.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.172-179
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• 1998

Valve lifter namely tappet is supported by lifter hole which is located upper side of camshaft in cylinder block transforms rotatic mvement of camshaft into linear movement and helps to open and shut the en-gine valve as an engine parts. The face of valve lifter which is continuously contacting with camshaft brings about abnormal wears such as unfair wear and early wear because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears therefore The valve lifter cast in me-tal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance As a results the optimum process conditions like injection condition mixture ratio and debonding process could be established. After sintering fine-sinered dual microstructure in which prior ${\alpha}$-SiC matches well with new SiC(${\beta}$-SiC) produced by reaction among the ${\alpha}$-SiC carbon and silicon was obtained. Based on the study it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100-1200 bending strength (300-350 Pa) fracture toughness(1.5-1.7 Mpa$.$m1/2) Through engine dynamo test-ing SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such as early fracture unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resis-tance relaibility and lightability.

• Journal of Korean Library and Information Science Society
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• v.51 no.1
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• pp.71-90
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• 2020

The purpose of this study is to find out changing process of 'Kyungsung Libraries' in the Japanese colonial era by comparing and analyzing through the books and Journals of Korea and Japan. The subject scopes of this study are as follows ; 1) 'Kyungsung Libraries' in Japan Chamber of Commerce and Industry founded by Japanese named, 'San Gu Jung(Yamaguchi Sei)' 2) 'Kyungsung Libraries' founded by 'Yoon Ik Sun' in 'Chiwoonjung' 3) 'Kyungsung Libraries' founded by 'Lee Bum Sung' beside 'Jongno Tapgol Park'. This study studies each three libraries and simultaneously, relationship between mutual relation of these three libraries and other libraries. As a results, the books of San Gu Jung(Yamaguchi Sei)'s library were inherited to those of other two libraries. Also, Despite of eagerly practicing public service of the age, however, independent development of each of two library founded by Koreans was very limited under the influence of Japanese colonial.