• Proceedings of the KWS Conference
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• 2005.06a
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• pp.370-376
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• 2005

Magnesium alloys are becoming important material for light weight car body, due to their low specific density but high specific strength. However they have a poor weldability, caused high oxidization tendency and low vapor temperature. In this study, the welding performance of magnesium alloys was investigated for automobile application. The materials were rolled magnesium alloy sheet contains Al and Zn such as AZ3l , AZ6l and AZ9l. Three types of welding process were studied, that were GTAW, Laser beam welding and FSW. To evaluate the weldability, we examined the appearance of welding bead. Also we checked bead shape and internal defects such as crack and porosity on cross section of welding bead. The mechanical property was measured for welded specimen by tensile test. For determination of the strength change by welding process, the hardness profile across the welding center was measured. For the results, the tensile properties of welded specimen were decreased obviously on all welding process. For the fusion welding process such as GTAW and laser beam welding, the surface of the welding bead was covered with oxidized magnesium dust but it was removed by simple cleaning work as wipe-out with tissue. Also under cut, that caused vaporization of base metal was occurred. for the friction stir welding, there was no oxidation, under-cut or internal defects. However it had poor weld performance, the reason was cleavage fracture occurred at plastic deformation zone. For welding of magnesium alloy, the laser beam welding process was recommended.

• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.5
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• pp.559-566
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• 2016

Cables for Towed Array Sonar System(TASS) were developed. In order to verify the performance of cables, environmental and operational conditions as well as functional requirements were investigated during design stage. Double armored high and low voltage integrated cable for towed body and two kinds of cables, armored and light weight power and optic hybrid cables for towed array sensor system were developed by modeling and simulation. Customized manufacturing process and test method, such as foam extrusion and dynamic fatigue test were applied to this development. In conclusion, underwater towed hybrid cable with high tensile strength and compact structure were developed.

• Preventive Nutrition and Food Science
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• v.10 no.2
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• pp.156-160
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• 2005

Salvia miltiorrhiza Radix root extracts (SMR) was evaluated for inhibition of the progress of bone loss induced by ovariectomy (OVX) in rats. We measured body weight and bone histomorphometry in sham, OVX and SMR-administered OVX rats. From light microscopic analyses, porous or erosive appearances were observed on the surface of trabecular bone of tibia in OVX rats, whereas those of the same bone in sham rats and in SMR-administered rats were composed of fine particles. The trabecular bone area and trabecular thickness in OVX rats were decreased by $50\%$ from those in sham rats, and these decreases were completely inhibited by administration of SMR for 7 weeks. In this study, the mechanical strength in femur neck was significantly enhanced by the treatment of SMR for 7 weeks. In OVX rats, free $T_3$ was normal in all cases, whereas free $T_4$ was significantly increased. Although there was no difference between OVX and SMR-administered rat in $T_3$ levels, we have found significant difference between them in $T_4$ level. These results strongly suggest that SMR may be beneficial for preventing bone loss in OVX rats.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.22-29
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• 2001

To evaluate the cutaneous injury in liver damaged rats by toluene application to the skin, toluene(35mg/㎤) was sequentially applied for 5 days to the dorsal skin of liver damaged rats with $CCl_4$ (6 times ever other day:0.1$m\ell$/100 g body weight-50% $CCl_4$in olive oil). The cutaneous ultrastructural changes were unexoectably not observed in liver from $CCl_4$-treated rats although necrotic liver damage appeared under light microscope. In these animals by the application of toluene to rat skin the cutaneous xanthine oxidase activity was significantly increased(p<0.05), but cytochrome P450 content was not different from that of the control or only $CCl_4$-treated rats. On the other hand, the cutaneous superoxide dismutase and catalase activities in liver damaged animals were significantly respectively(p<0.05, p<0.001), decreased by toluene application to the skin compared with control and especially the former enzyme activity was significantty decreased(p<0.01), compared with that of liver damaged rate rat but glutathione peroxidase, glutathione-S-transferase activities were not significantly different from those of the control or liver damaged rats. Futhermore, the reduced gluathione content of skin was also significantly decreased by toluene application to the liver damaged animals. In conclusion, the great deposits of cerrous peroxide and ultramorphological changes in skin tissue of liver damaged animals by toluene application may be responsible for the oxygen free radical.

• Toxicological Research
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• v.12 no.2
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• pp.259-263
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• 1996

The preventive effects of ginseng and aloe extract on cigarette smoke-induced hepatotoxicity to Spague-Dawley rats were investigated. The experimental rats were exposed smoke by inhalation for 5 weeks, 3 times per day, and 15 minutes each time. Also ginseng and aloe extract (Group G+A), aloe (Group A) or ginseng (Group G) were administered to each group, but the positive control rats (Group C) were exposed smoke without any other special treatments. Group C showed decreased food intake and increased water consumption. Also the reduction of body weight and the increase in serumAST, ALT, triglyceride and alkaline phosphatase were observed. The relative liver weights of group C were increased and the hepatic parenchyma revealed light brownish red grossly. On histopathologic observation, the hepatocytes of group C animals exhibited diffuse swelling which narrowed the, sinusoidal lumen and disarrayed the hepatic cord-like arrangement. Diffuse necrosis of the hepatocytes was also observed. However, degeneration and necrosis of the hepatocytes were milder in group G+A. In the case of group A, the damage was moderate, while the group G showed marginal improvement from group C. Electronmicroscopically, peroxisome increased and mitochodria decreased in group C. Various hepatic damages related to smoking in group C revealed recovering tendency in group G+A. This study indicated that daily administration of ginseng and aloe could decrease and even prevent cigarette smokeinduced hepatotoxicity.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.33-33
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• 2011

Artificial silk that called "Ponggi (Gyeongsangbukdo, Korea) In-Gyeun" in Korea is entirely viscose rayon of which made main component refined larches and cotton linter. It also is natural fabrics with light weight, cool texture, free from the body and well ventilation property, so, feel good touch during the wearing. In addition, it often used as summer cloth and bedding because it has good absorbancy to perspiration and antistatic. The "Hanji", made of paper mulberry, is known as useful material for human. In this research focused on dyeability of Artificial silk/paper mulberry mixed fabrics using Dendropanax morbifera Lev.(called as "Hwangchil") Especially, the results were in comparison to the dyeing properties of Hwangchil with liquid/solid fermentation or not. As the results, The ${\Delta}E$ difference was dominated when the fabric dyed with fermentation by solid state at $60^{\circ}C$. And it was confirmed that the pH of fermented dye had an important influence in the coloration.

• Journal of Welding and Joining
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• v.28 no.5
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• pp.99-105
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• 2010

Inverter DC resistance spot welding process has been very widely used for joining such as automotive body sheet metal. Because the lobe area of DC welding is larger than AC welding and DC welding has low electrode wear. So the use of Inverter DC resistance spot welding process has been further increased. And the application of high tensile steel is growing for light weight vehicle. To improve the weldability of high strength steel, the development of Inverter DC resistance spot welding system is more conducted. However, Inverter DC resistance spot welding system has a few problems. Current waveform is unstable and the expulsion has been occurred by characteristics of steel. In this study, inverter DC resistance spot welding system was made. And Fuzzy control algorithm was applied for constant current. The genetic algorithm was applied to optimize the fuzzy scaling factors, in order to optimize the fuzzy control.

• Journal of the Korean Society of Mechanical Technology
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• v.13 no.1
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• pp.105-112
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• 2011

Increasing needs for light weight and high safety in modern automobiles induced the wide application of high strength steels in automotive body structures- The main difficulty in the forming of sheet metal parts with high strength steel is the large amount of springback including sidewall curl and twist in channel shaped member parts- Among these shape defects, twist occurs frequently and requires numerous reworks on the dies to compensate the shape deviation- But until now, it seems to be no effective method to reduce the twist in the forming processes- In this study, a new forming process to reduce the twist deformation during the forming of automotive structural member was suggested- This method consists of forming and restriking of embosses on the sidewall around the stretch flanging area of the part- and was applied in the forming process design of an automotive front side inner member with high strength steel- To evaluate the effectiveness of the method, springback analysis using $Pamstampa^{tm}$ was done- Through the analysis results, the suggested method was proven to be effective in twist reduction of channel shaped parts with stretch flanging area.

• Journal of the Korea Society of Computer and Information
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• v.24 no.1
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• pp.151-158
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• 2019

This study aimed to analyze the research trend related on obesity in physical education in Korea through the keyword network analysis and to establish a basic database for effective design of prospective studies. To achieve it the study crawled co-occured keywords with 'obesity' and 'physical education' from RISS and analyzed the list from 1990 to 2018. They include 25 journal papers and 38 dissertations. The results are as follows. First, recent 30 years 63 papers published in Korea with 'Obesity' and 'Physical Education', and there were 144 related keywords. Second, analyzing journals which have 'Obesity' and 'Physical Education', co-occured keywords in 4 centrality were 24 keywords(student, Korea, prevention, effect, level, body, activation, actual condition, lesson, child, investigation, participation, book, cause, activity, normal, degree, nutrition, physical strength, weight, elementary, light, inquiry, health), and 37 keyword occurred in top 30. Lastly, by CONCOR analysis the result could be divided into 2 clusters. One consists of the object of obesity and its invervention, and the other consists of negative keywords of obesity and its preliminery dimenstion. Through the result, this study showed the research trend which involves the concept of obesity in physical education in Korea. Through the result, prospective obesity research in physical education in Korea would be promoted.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.495-504
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• 2021

Three-dimensional printing (3DP) applications possess substantial versatility within surgical applications, such as complex reconstructive surgeries and for the use of surgical resection guides. The capability of constructing an implant from a series of radiographic images to provide personalized anatomical fit is what makes 3D printed implants most appealing to surgeons. Our objective is to describe the process of integration of 3DP implants into the operating room for spinal surgery, summarize the outcomes of using 3DP implants in spinal surgery, and discuss the limitations and safety concerns during pre-operative consideration. 3DP allows for customized, light weight, and geometrically complex functional implants in spinal surgery in cases of decompression, tumor, and fusion. However, there are limitations such as the cost of the technology which is prohibitive to many hospitals. The novelty of this approach implies that the quantity of longitudinal studies is limited and our understanding of how the human body responds long term to these implants is still unclear. Although it has given surgeons the ability to improve outcomes, surgical strategies, and patient recovery, there is a need for prospective studies to follow the safety and efficacy of the usage of 3D printed implants in spine surgery.