• Nuclear Engineering and Technology
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• v.52 no.3
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• pp.647-653
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• 2020

Stainless steel is used commonly in nuclear applications for shielding radiation, so in this study, three different types of new stainless steel samples were designed and developed. New stainless steel compound ratios were determined by using Monte Carlo Simulation program Geant 4 code. In the sample production, iron (Fe), nickel (Ni), chromium (Cr), silicium (Si), sulphur (S), carbon (C), molybdenum (Mo), manganese (Mn), wolfram (W), rhenium (Re), titanium (Ti) and vanadium (V), powder materials were used with powder metallurgy method. Total macroscopic cross sections, mean free path and transmission number were calculated for the fast neutron radiation shielding by using (Geant 4) code. In addition to neutron shielding, the gamma absorption parameters such as mass attenuation coefficients (MACs) and half value layer (HVL) were calculated using Win-XCOM software. Sulfuric acid abrasion and compressive strength tests were carried out and all samples showed good resistance to acid wear and pressure force. The neutron equivalent dose was measured using an average 4.5 MeV energy fast neutron source. Results were compared to 316LN type stainless steel, which commonly used in shielding radiation. New stainless steel samples were found to absorb neutron better than 316LN stainless steel at both low and high temperatures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.5
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• pp.208-215
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• 2016

This study was conducted to improve the performance of low-temperature vacuum dryer by applying desiccant to cold trap. Performance evaluation was carried out using several desiccants. The amounts of absorption and diffusivity were measured based on analytic model. Results of desiccant performance evaluation revealed that silica-gel had the most excellent performance for conditions of low-temperature vacuum drying process. Silica-gel was applied to cold trap for evaluating the drying performance. The experiment results showed that the drying time was extended as the thickness of sample was increased due to increased heat and mass transfer resistance of drying sample. In addition, as heating plate temperature was increased, drying time was decreased due to increased evaporation pressure of drying sample. Furthermore, drying time with desiccant was decreased approximately 20% than that without desiccant.

• Geotechnical Engineering
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• v.13 no.2
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• pp.39-54
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• 1997

Laboratory testings were carried out on plastic board drains (PBDs) using large scale test apparatus to evaluate the physical properties and the drainage performance. The test results reveal that the domestic products of PBDs are well compared with the foreign prod acts as far as the quality and drainage performance are concerned. It has also been confirmed that the discharge capacity decreases with time in such a way that the air bubbles are entrapped inside kinky PBDs and these air bubbles block the water flow through PBDs. It has been found that the vacuum pressure iseffectively applicable to recover the discharge capacity affected by the entrapped air bubbles.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.9-12
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• 2015

NbN thin films were deposited on thermally oxidized Si substrate at room temperature by using reactive magnetron sputtering in an $Ar-N_2$ gas mixture. Total sputtering gas pressure was fixed while varying $N_2$ flow rate from 1.4 sccm to 2.9 sccm. X-ray diffraction pattern analysis revealed dominant NbN(200) orientation in the low $N_2$ flow rate but emerging of (111) orientation with diminishing (200) orientation at higher flow rate. The dependences of the superconducting properties on the $N_2$ gas flow rate were investigated. All the NbN thin films showed a small negative temperature coefficient of resistance with resistivity ratio between 300 K and 20 K in the range from 0.98 to 0.89 as the $N_2$ flow rate is increased. Transition temperature showed non-monotonic dependence on $N_2$ flow rate reaching as high as 11.12 K determined by the mid-point temperature of the transition with transition width of 0.3 K. On the other hand, the upper critical field showed roughly linear increase with $N_2$ flow rate up to 2.7 sccm. The highest upper critical field extrapolated to 0 K was 17.4 T with corresponding coherence length of 4.3 nm. Our results are discussed with the granular nature of NbN thin films.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.982-990
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• 1999

YSZ/LSM composite cathode was fabricated by dip-coating of YSZ sol on the internal pore surface of a LSM cathode followed by sintering at low temperature (800-100$0^{\circ}C$) The YSZ coating significantly increased the TPB(Triple Phase Boundary) where the gas the electrode and the electrolyte were in contact with each other. Sinter the formation of resistive materials such as La2Zr2O7 or SrZrO3 was prevented due to the low processing temperature and TPB was increased due to the YSZ film coating the electrode resistance (Rel) was reduced about 100 times compared to non-modified cathode. From the analysis of a.c impedance it was shown that microstructural change of the cathode caused by YSZ film coating affected the oxygen reduction reaction. In the case of non-modified cathode the RDS (rate determining step) was electrode reactions rather than mass transfer or the oxygen gas diffusion in the experimental conditions employed in this study ($600^{\circ}C$-100$0^{\circ}C$ and 0,01-1 atm of Po2) for the YSZ film coated cathode however the RDS involved the oxygen diffusion through micropores of YSZ film at high temperature of 950-100$0^{\circ}C$ and low oxygen partial pressure of 0.01-0.03 atm.

• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.397-401
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• 2008

The nanoparticle-agglomerates are synthesized by laser ablation, which have the morphology of dendrite structure. The filtration performance of a conventional micron-fibrous metal filter was improved by adhering nanoparticle-agglomerates onto the filter surface. The Sintered-Nanoparticle-Agglomerates-adhered Filter (SNAF) adhered with nanostructured material was made by heat treatment after deposition of nanoparticle-agglomerates sintered in aerosol phase onto the micron-fibrous metal filter. As the sintering temperature increases, the pressure drop of the filter increases a little but the filtration efficiency increases remarkably. This is due to increase of surface area of nanoparticle-agglomerates adhered onto the micron-fibrous metal filter.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.838-845
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• 2006

Recently construction work in Korea, demands of favorable condition ground had been increased with industrialization acceleration and economic growth. However, because of limited land space, it was so hard to ensure favorable condition grounds that construction work proceeds until soft ground area on plans of road, railroad and industrial complex. In this case, soft ground improvement was required such as a stone column method. Stone column method, making a compaction pile using crushed stone, is a soft ground improvement method. However, stone column method is difficult to apply to the ground which is not mobilized enough lateral confine pressure because no bulging failure resistance. Hence, in present study, evaluates the stone columns reinforced by geogrid for settlement reduction and wide range of application of stone columns. Triaxial compression tests were conducted for evaluation which is about behavior characteristics of stone column on replacement rate. Then, 3-dimensional numerical analysis were conducted for application of stone column reinforced by geogrid as evaluate behavior characteristics and settlement reduction effect of stone column reinforced by geogrid on reinforcing depth change of geogrid.

• Journal of the Korean Ceramic Society
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• v.42 no.7 s.278
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• pp.455-460
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• 2005

Deposition of TiN$_{x}$ film was conducted with a DC sputtering technique. The effect of the processing parameters such as substrate temperature, deposition time, working pressure, bias power, and volumetric flowing rate ratio of Ar to N$_{2}$ gas on the resistivity of TiN$_{x}$ film was systematically investigated. Three kinds of substrates, soda-lime glass, (100) Si wafer, and 111m thermally grown (111) SiO$_{2}$ wafer were used to explore the effect of substrate. The phase of TiN$_{x}$ film was analyzed by XRD peak pattern and deposition rate was determined by measuring the thickness of TiNx film through SEM cross-sectional view. Resistance was obtained by 4 point probe method as a function of processing parameters and types of substrates. Finally, optimum condition for synthesizing TiN$_{x}$ film having lowest resistivity was discussed.

• Journal of East-West Nursing Research
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• v.14 no.2
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• pp.47-53
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• 2008

Purpose: Metabolic syndrome (also known as insulin resistance syndrome) represents a constellation of hypertriglyceridemia, hypertension, impaired glucose tolerance, and obesity. Presently, the influence of various factors on metabolic syndrome was assessed in patients of a university hospital comprehensive medical examination center. Methods: Age, sex, blood pressure, height, weight, triglyceride level, high-density lipoprotein cholesterol, and glucose levels were measured in 67 people (37 males and 30 females). These factors were correlated with tobacco use, alcohol consumption, and exercise habits. Metabolic syndrome and abdominal obesity were assessed according to NCEP-ATP III criteria and the Asia-Pacific guidelines (male obesity defined as a waist circumference exceeding 90 cm), respectively. Data was analyzed using t-test, 2-test, and logistic regression. Results: Respective percentages were: tobacco use (14.9% of the 67 people), no tobacco use (85.1%), alcohol consumption (62.7%), no alcohol consumption (37.3%), regular exercise (25.4%), no regular exercise (74.6%). Logistic regression analysis revealed a gender-related odds ratio of 2.3 for metabolic syndrome and no exercise. Conclusions: Weight reduction and physical exercise may decrease the prevalence of metabolic syndrome. Early identification of metabolic syndrome and risk factor modification is prudent in cases of obesity, diabetes, hyperlipidemia, and hypertension.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.8
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• pp.110-116
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• 2020

Aircraft hydraulic oil reservoirs made with aluminum 7075 have an anodized coating to enable airtightness and corrosion resistance. To maintain a stable oil pressure, the internal surface roughness of the reservoir should be less than approximately 0.2 ㎛. To this end, precision polishing must be performed. However, ensuring the processing quality is challenging, as most polishing operations are performed manually, owing to which, the inner surface roughness is not uniform, and the product quality is irregular. Therefore, we developed a special superfinishing machine to realize the efficient inner polishing of an aircraft hydraulic oil reservoir, by using an abrasive film to improve the process throughput and uniformity. In the experiment involving the superfinishing of an anodized aluminum 7075 cylinder specimen by using the proposed machine, a higher surface roughness than that achieved in the repetitive manual polishing process could be realized.