• 대한예방의학회:학술대회논문집
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• 2001.10a
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• pp.155-156
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• 2001

• The Journal of the Korean dental association
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• v.12 no.3
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• pp.195-198
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• 1974

The purpose of this study is to obtain the histopathological change of dentin and pulp when the prepared cavity is exposed to oral fluid without protection. The results were as follows: 1. Hyperemia of pulp blood vessel and round cell infiltration in odontoblast layer observed on the one week experimental dogs. 2. Marked edematous change, round cell infiltration, fibrotic change and prolif eration of collagenous fiber showed on the 8 week experimental dogs. 3. Prepared cavity should be protected by the biologically accepted lining mater ials regardless of cavity depth.

• International Journal of Air-Conditioning and Refrigeration
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• v.12 no.4
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• pp.192-197
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• 2004

A capillary tube, which is a common expansion device in small sized refrig-eration and air-conditioning systems, should be redesigned properly to establish an optimum operation cycle of a refrigerating system with alternative refrigerants. Based on experimental data for R-22, R-290, and R-407C, an empirical correlation is developed to predict mass flow rate through capillary tubes. Dimensionless parameters are derived from the Buckingham Pi theorem, considering the effects of operating conditions and capillary tube geometry on mass flow rate. Approximately $97\%$ of the present data are correlated within a relative deviation of $\pm\;10\%.$ The present correlation also predicts the data obtained from open literature within $\pm\;15\%.$ In addition, rating charts of refrigerant flow rate for R-12, R-22, R-134a, R-152a, R-407C, R-410A, R-290, and R-600a are developed.

• Korean Journal of Materials Research
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• v.18 no.8
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• pp.432-437
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• 2008

Titanium oxide films and powders are attached onto carbon cloths via RF reactive sputtering and an epoxy resin mixture, respectively. $TiO_2$/carbon composite materials were used to investigate the photoelectrochemical degradation of perchlorate ions in water. The energy band gaps of the RF-sputtered $TiO_2$ thin films ranged from 3.35-3.44 eV. A photocurrent of the powdered $TiO_2$ as illuminated by ultra-violet light for 30 min. was $2.79\;mA/cm^2$. Perchlorate ions in water were shown to be degradable by a UV-illuminated $TiO_2$ powder/carbon/Nafion/carbon composite.

• Journal of the Korean Ceramic Society
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• v.35 no.6
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• pp.551-558
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• 1998

Detection of microcrack in {{{{ {Al }_{2 } {O }_{3 } }} ceramics were studided by AE(acoustic emission) technique with 4-point bending test in order to evaluate the fracture process and formation of microcrack. Fully-dense alu-mina ceramics having a different grain size were fabricated by varing the hot-pressing temperature. The grain size of alumina increased with increasing the hot-pressing temperature whereas the bending strength decreasd. The microcracks were observed by SEM and TEM. The generation of AE event increased with increasing the applied load and many AE event was generated at maximum applied load. Alumina with smaller grain size shows the generation of many AE event resulting in an increase of microcrack formation. An intergranular fracture is predominantly observed in fine-grained alumina whereas intragranular fracture occurs predominantly in coarse-grained alumina,. Analysis of micorstructure and AE prove that primary mi-crocracks occur within grain-boundaries of alumina. The larger microcracking were formed by the growth and/or coalesence of primary microcracks. Then the materials become to fracuture by main crack gen-eration at the maximum applied load.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.2
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• pp.33-40
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• 1997

Recently, there are an increasing needs for high speed rotating spindle which is an important mechanical ele- ment for a high efficiency machine tool in order to shorten machining time and cut production costs. The heat gen- eration is the most important problem in the motor integrated spindle. In this study, the effects of temperature distribution and thermal behavior according to the oil-air lubrication and cooling conditions are investigate theo- retically and experimentally on the motor-integrated spindle under unloading condition. The experimental spin- dle system is composed with the angular contact steel ball bearings, oil-air lubrication, air or oil jacket cooling system. To analyze the thermal behavior and cooling characteristics for the motor integrated spindle, the analysis using the finite element method is carried out. The analytical results are compared with the experimental results.

• Journal of the Korean Society of Costume
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• v.41
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• pp.153-168
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• 1998

The purpose of this study is to examine, specifically, the external and internal characteristics of anti-fashion expression in the Korean student movement after the 1945 Liberation. The dress expressed in the student movement represented the purity of student and characterized resistance, and this character expressed strongly in 80s, faded from middle of 90s. Until the 60s, the student movement was not characterized by, so activist students wore dress and suits. It symbolized students as an elite group of society. They added on head-bands to express resistance. In the 70s, activist students wore school uniforms, school military training wear, blue jeans and loose shirts in demonstrations. They tried to express re-bellion against the government and the older gen-eration. In the 80s, the period was remarkably distingusihing by the economic growth at that time. Activist students wore T-shirts with Korean letters and popular paintings specially made, Korean costumes, wrapped in the Taggeuki (Korean national flag), and refused wear on jeans because of anti-Americanism. They also wore masks, muffled their faces, and got their heads shaved. These anti-fashions are very strong expressions for the national independence spirit, national traditional heitage, anti-foreign power and anti-American. In the early 90s, activist students wore reformed Korean costumes specially made group uniforms, after that they wore casual everyday clothes with caps. They tried to express remarkable resistance in the early 90s, but after the mid-90s expression of resistance weakened and faded, so there was no distinction between activist and non-activist. There are the reasons why the student movement changed after the peaceful transfer of political power.

• Microbiology and Biotechnology Letters
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• v.29 no.1
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• pp.12-17
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• 2001

Aspergil-lus coreanus NR-15 and Aspergilus oryzae NR-2-5 from traditional Korean Nuruk were selected as parental strains producing starch hydrolysis enzyme. Xll(Arginine-) mutant from A. coreanus NR 15-1 showed high glu-doamylase activity and total acid productivity. Z6(Adenine-) mutant from A. oryzae NR2-5 showed the highest $\alpha$-amylase activity. Therefore, both XII and Z6 mutants were selected and investigated for the optimal conditions of protoplast formation for protoplast fusion. Mixture of equal amount of cellulase and driselase(10mg/ml each) was the most effective as lytic enzymes. The optimal pH and temperature for protoplast formation were 5.0 and $30^{\circ}C$, respectively. The most effective reaction for protoplast formation time was 4 hours. The maximum of protoplst for- mation of Xll mutant and Z6 mutant were $6.54$\times$10^{7}$ protoplasts/ ml and $3.04$\times$10^{ 7}$ protoplasts/ml, and the regen-eration frequencies of the protoplasts were 11.3% and 11.6%, respectively. The size of the protoplasts from X11 and Z6 mutants were 3~6 $\mu\textrm{m}$ and 4~9$\mu\textrm{m}$, respectively.

• The KIPS Transactions:PartD
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• v.11D no.7 s.96
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• pp.1427-1434
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• 2004

Database system benchmarks, which are usually evaluated to use the maximized resource in order to get the best results, arc not likely to simulate the real environment. We propose a workload generator that helps benchmarks be executed in the environment similar to a real world. The workload generator can create memory-bound, CPU-bound, and I/O-bound workloads. The workload generator allows users to create an integrated workload. which is similar to a real workload users run across in practice. Finally, we conducted the experiments that the Wisconsin benchmark was performed with the TPC-C and with the workload generation tool, and showed the feasibility of the proposed workload gen-eration tool comparing with two experimental results.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E3
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• pp.153-163
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• 2002

A laboratory- scale dual-column biofilter system was used to study the biofiltration of dimethyl disulfide (DMDS). The gas flow rate and DMDS concentration to the biofilter were varied to study their effect on the remov-al of dimethyl disulfide. Operating parameters such as pH, temperature, and water content were monitored during the biofilter operation and necessary precautions were taken to keep these parameters within the acceptable limits. It was observed that the removal efficiency of DMDS was optimal at neutral pH values. After five month op-eration, the neutralization of the filter beds with sodium carbonate became necessary for the optimum operation of the biofilters. The microbial population already present in the compost mixtures was found to be adequate in treat-ing DMDS. The compost mixtures were found to be similar in terms of biofiltration efficiency of DMDS. However, pressure drops observed in the first column compost mixture (compost/ peat mulch) was extremely high, making this compost economically not feasible. The second mixture (compost/bark) provided pressure drops within accept-able limits. A minimum residence time of 30 seconds at the optimal operating conditions appeared to be adequate for achieving high removal efficiencies (>90%).