• Transactions of the Korean Society of Automotive Engineers
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• v.20 no.2
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• pp.98-102
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• 2012

Increasing the fuel economy has been an inevitable issue for the development of new cars, and one of the important measures to improve the fuel economy is to decrease the vehicle weight. In order to obtain this goal, the researches about lighter, stronger and the well impact absorbing bumper impact beam have been studied without sacrificing bumper safety. In this study, the overall weight reduction possibility of rear bumper impact beam could be examined based on the variation of frontal, offset and corner impact crash capability by substituting a ultra high strength steel material (boron steel ) having tensile strength of 1.5 GPa grade instead of conventional steels. In addition, the section variations (open section, closed section, open section with 5 stays) of the bumper impact beam structure were examined carefully. It could be reached that this analysis could be well established and be contributed for design guide and the optimum design conditions of the automotive rear bumper impact beam development.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1312-1316
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• 2007

Strip casted and rolled magnesium sheet is become exiting material for car manufacturer, due to its better formability and specific strength compare with conventional extruded sheet. TWB technology was attractive for car body designer, because it saves the weight of the car without strength loss. In this study, the laser welding performance of magnesium sheet was investigated for Mg TWB panel manufacturing. The material was strip casted and rolled magnesium alloy sheet contains 3 wt% Al and 1 wt% Zn (AZ31). Lamp pumped Nd:YAG laser of 2kW was used and its laser light was delivered by optical fiber of 0.6mm core diameter to material surface with focusing optics of 200mm focal length for TWB welding. The microstructure of weld bead was investigated to check internal defects such as inclusion, porosity and cracks. Also mechanical properties and formability were evaluated for press forming of car body. For the results, there was no crack but inclusion or porosity on weld at some conditions.The tensile strength of weld was over 95% of base metal. Inner and outer panel of engine hood were press formed and assembled at elevated temperature.

• Korean Journal of Community Nutrition
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• v.7 no.6
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• pp.803-813
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• 2002

The purpose of this study was to investigate the anthropometric and blood biochemical characteristics, the dietary behaviors and health-related lifestyles of obese children in Incheon. A cross-sectional survey was conducted using anthropometric measurements, biochemical assessments and questionnaire analysis. The subjects included 7,055 obese children residing in the Incheon area (from 106 elementary schools). The degree of obesity was classified using the Obesity Index (OI) as light 20% ＜ OI ＜ 30% ; Medium 30% ＜ OI ＜ 50% ; Severe 50% ＞ OI. The statistical analysis was conducted using SPSS 10.0 program. Most subjects fell within the medium range of obesity. Most subjects had dietary problems such as overeating, unbalanced meals and skipping breakfast. The ratio of boy subjects eating green and yellow vegetables was lowe. when compared to that of the girl subjects. The boy subjects exercised more frequently and longer than the girls. As the Obesity Index increased, hypercholesterolemia significantly increased. The blood cholesterol levels of the subjects were positively correlated with body fat, waist/hip ratio and BMI; HDL cholesterol levels of the subjects were negatively correlated with the anthropometric data and the LDL cholesterol levels of the subjects were positively correlated with body fat. The blood triglycerides levels of the subjects were positively correlated with body weight, body fat, waist/hip ratio and BMI. Therefore, proper nutritional education and intervention are required for an improvement of obese children＇s dietary behavior, heath-related factors and blood lipid profiles.

• International Journal of Industrial Entomology and Biomaterials
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• v.3 no.1
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• pp.101-103
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• 2001

The wild silkmoth, Samia cynthia pryeri, was firstly collected at Miryang, Korea. The development and quantitative characters of S. cynthia preyri in the laboratory condition were analysed. The larval body color of dark yellow green or light yellow green of the S. cynthia pryeri was changed into white color during the molting period, and the yellowish bristles in younger larvae were changed into fade green color in advanced stage larvae. Aralia elata and Zanthoxylum piperitum were newly identified as host plants to S. cynthia pryeri. Cocoon weight and cocoon shell percentage were average 2.14 g and 12.3 %, respectively. In addition, the morphology of the silkgland was different from that of the domestic silkworm,Bombyx mori, but was identical with that of the wild silkmoth, Antheraea yamamai.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.2
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• pp.47-51
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• 2007

Special quality of automobile clutch master cylinder(CMC) and analyzed aluminum, plastic material comparison. Efficiency of plastic master cylinder can modularize higher, light weight anger of parts, several piece parts by single parts, prove NVH(Noise, Vibration, Harshness) than aluminum master cylinder as analysis result. Also, structure is easy simplicity, exchange, maintenance costs can be reduced and decrease environmental pollution because recycling is superior. According as content of glass fiber increases, mechanical properties of matter of material increase equally and glass fiber changed variously by condition on manufacturing process. Through comparison analysis with Plastic Body development connection site, did verification.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.93-99
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• 2015

Economic burden of work-related musculoskeletal disorder(WMDs) is increasing. Known causes of WMDs include improper posture, repetition, load, and temperature of workplace. Among them, improper postures play an important role. A smart sensor called SensorTag is employed to estimate the trunk postures including flexion-extension, lateral bend, and the trunk rotational speeds. Measuring gravitational acceleration vector in the smart sensor along the tri-orthogonal axes offers an orientation of the object with the smart sensor attached to. The smart sensor is light in weight and has small form factor, making it an ideal wearable sensor for body posture measurement. Measured data from the smart senor is wirelessly transferred for analysis to a smartphone which has enough computing power, data storage and internet-connectivity, removing need for additional hardware for data post-processing. Based on the estimated body postures, WMDs risks can be conviently gauged by using existing WMDs risk assesment methods such as OWAS, RULA, REBA, etc.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.143-150
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• 1998

The evaluation of joint fatigue strength of light weight materials for electrical vehicle body has been performed through single lap joint tests with the design parameters such as joint style, adherend, bonding overlap length and bonding thickness. Fatigue strength was evaluated through 5-Hz, tension-tension, load controlled test with the stress ratio zero value. It is experimentally observed that fatigue strength of joint increases for the increase of overlap length. The combinations of Al-Al and Al-FRP adherends show that fatigue strength of joint is hardly changed for the increase of bonding thickness, but FRP-FRP adherend specimen shows that fatigue strength of joint increases after decreases for the increase of bonding thickness. Al-Al adherend specimen has much higher fatigue length than Al-FRP and FRP-FRP adherend specimens. Riveting at adgesive bonded joint gives little effect on fatigue strength.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.321-326
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• 2008

Light weight of vehicles by composite materials makes possible high speed, energy saving, and low repair cost. As Bimodal Tram and Tilting Train eXpress(TTX) use carbon composite material for their bodies, safety for passengers and electrical devices against unexpected failures has been issued more than ever. Lightning strike which generates high voltages and large currents is the worst case for the safety of passengers and devices. With this background, we experimentally investigated the insulation breakdown phenomena on carbon composite materials by the application of lightning surge voltage and current. From the experimental results, we could estimate whether the composite body is safe or not for the inside passengers and devices against lightning strikes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.150-151
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• 2013

Recently, the internal space organization of the building changes to the frame construction and flat slab construction in the wall type structure. And the use of light weight panel changing the internal joint use easily is increased. Therefore, in this research, the length change characteristic that the magnesium chloride addition rate reaches to the magnesium curing body tries to be studied. It could confirm according to the length change specific result that the magnesium chloride amount of addition reaches to the magnesium oxide curing body to expand. And the thing described below was the large-scale expansion the magnesium oxide addition rate 60%. And it showed up as 50, 40, 30, 20, and order of 10s (%). It could look at to form the hydrate of the SEM picture result needle-shaped of the Hardened.

• Development and Reproduction
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• v.20 no.2
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• pp.109-118
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• 2016

This study monitored the morphological development of embryo, larvae and juvenile yellowtail kingfish, Seriola lalandi, for their aquaculture. The fertilized eggs obtained by natural spawning were spherical shape and buoyant. Fertilized eggs were transparent and had one oil globule in the yolk, with an egg diameter of $1.35{\pm}0.04mm$ and an oil globule diameter of $0.32{\pm}0.02mm$. The fertilized eggs hatched 67-75 h after fertilization in water at $20{\pm}0.5^{\circ}C$. The total length (TL) of the hatched larvae was $3.62{\pm}0.16mm$. During hatching, the larvae, with their mouth and anus not yet opened. The yolk was completely absorbed 3 days after hatching (DAH), while the TL of post-larvae was $4.72{\pm}0.07mm$. At 40 DAH, the juveniles had grown to $30.44{\pm}4.07mm$ in TL, body depth increased, the body color changed to a black, yellow, and light gray-blue color, and 3-4 vertical stripes appeared. At 45 DAH, the juveniles were $38.67{\pm}5.65mm$ in TL and $10.10{\pm}0.94mm$ in body depth. The fish were green with a light orange color, with 7 faint green-brown stripes on the sides of their body. At 87 DAH, the juveniles had grown to 236.11 mm in TL, 217.68 mm in fork length, and 136.5 g in weight. The fish resembled their adult form, with a light yellow-green body color, loss of the pattern on the sides of their body, and a yellow coloration at the tip of the caudal fin.