• Journal of Welding and Joining
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• v.14 no.3
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• pp.48-57
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• 1996

A study was made to examine the characteristics of base metal and stress relief cracking(SRC) of heat affected zone(HAZ) for HY-100 and Cu-bearing HSLA-100 steels. The Gleeble thermal/mechanical simulator was used to simulate the SRC/HAZ. The details of mechanical properties of base plate and SRC tested specimens were studied by impact test, optical microscopy and scanning electron microscopy. The specimens were aged at $650^{\circ}C$ for HSLA-100 steel and at $660^{\circ}C$ for HY-100 steel and thermal cycled from $1350^{\circ}C$ to $25^{\circ}C$ with a cooling time of $\Delta$t_${800^{circ}C/500^{circ}C}$=21sec. corresponds to the heat input of 30kJ/cm. The thermal cycled specimens were stressed to a predetermined level of 248~600MPa and then reheated to the stress relief temperatures of $570~620^{\circ}C$. The time to failure$(t_f)$ at a given stress level was used as a measure of SRC susceptibility. The strength, elongation and impact toughness of base plate were greater in HSLA-100 steel than in HY-100 steel. The time to failure was decreased with increasing temperature and/or stress. HSLA-100 steel was more susceptible to stress relief cracking than HY-100 steel under same conditions. It is thought to be resulted from the precipitation of $\varepsilon$-Cu phase by dynamic self diffusion of solute atoms. By the precipitation of $\varepsilon$-Cu phase, the differential strengthening of grain interior relative to grain boundary may be greater in the Cu-bearing HSLA-100 steel than in HY-100 steel. Therefore, greater strain concentration at grain boundary of HSLA-100 steel results in the increased SRC susceptibility. The activation energies for SRC of HSLA-100 steel are 103.9kcal/mal for 387MPa and 87.6kcal/mol for 437MPa and that of HY-100 steel is 129.2kcal/mol for 437MPa.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.186-189
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• 1996

A study was made to examine the characteristics of base metal and stress relief cracking(SRC) of heat affected zone(HAZ) for HY-100 and Cu-bearing HSLA-100 steels. The Gleeble thermal/mechanical simulator was used to simulate the SRC/HAZ. The details of mechanical properties of base plate and SRC tested specimens were studied. The specimens were aged at $650^{\circ}C$ for HSLA-100 steel and at 66$0^{\circ}C$ for HY-100 steel and thermal cycled from 135$0^{\circ}C$ In $25^{\circ}C$ with a cooling time of $\Delta$ $t_{800^{\circ}50}$ $0^{\circ}C$/=21sec. corresponds to the heat input of 30kJ/cm. The thermal cycled specimens were stressed to a predetermined level of 248~600MPa and then reheated to the stress relief temperatures of 570~62$0^{\circ}C$. The time to failure( $t_{f}$) at a given stress level was used as a measure of SRC susceptibility. The strength, elongation and impact toughness of base plate were greater in HSLA-100 steel than in HY-100 steel. The time to failure was decreased with increasing temperature and/or stress. HSLA-100 steel was more susceptible to stress relief cracking than HY-100 steel under same conditions. It is thought to be resulted from the precipitation of $\varepsilon$-Cu phase by dynamic self diffusion of solute atoms. Therefore, greater strain concentration at grain boundary of HSLA-100 steel results in the increased SRC susceptibility.y.

• Journal of Physiology & Pathology in Korean Medicine
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• v.30 no.2
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• pp.101-108
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• 2016

This study is conducted to investigate vasorelaxant effect of Corni Fructus(CF) on rabbit carotid artery. To determine vasorelaxant effect of CF on rabbit carotid artery, arterial sections with intact or removed endothelium were used in this organ bath study. After being contracted by phenylephrine(PE), arterial sections were treated with CF extract in a dose-dependent manner. To identity its mechanism, the contracted arterial sections by PE were pretreated with indomethacin(IM), tetraethylammonium chloride(TEA), Nω-nitro-L-arginine(L-NNA) or methylene blue(MB) and 1.0 ㎎/㎖ CF extract. We also studied to confirm the effect on influx of extracellular calcium chloride(Ca²⁺) of the CF extract in rabbit carotid artery. To measure the cytotoxicity of the CF extract, cell viability of human umbilical vein endothelial cell(HUVEC) was measured by MTT assay. Generation of nitric oxide(NO) was also measured by Griess reagent. The arterial sections with intact endothelium were relaxed significantly by CF extract, but this effect was inhibited in the arterial sections with damaged endothelium. The vasorelaxant effect was inhibited significantly when arterial sections were pretreated with IM, TEA, L-NNA, MB. In Ca²⁺-free krebs solution, increasing of arterial contraction by Ca²⁺ was also inhibited by CF significantly. The treatment of CF extract increased NO concentration in HUVEC. This study suggested that the vasorelaxant effect of CF extract would be related with endothelium derived relaxing factor(EDRF) such as NO, prostacyclin(PGI₂), endothelium derived hyperpolarization factor(EDHF).

• Journal of Plant Biotechnology
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• v.42 no.1
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• pp.55-59
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• 2015

The extracts of Aruncus dioicus were investigated for anti-oxidant and biological activities in order to verify its potential as functional ingredients of cosmetic products. The ethyl acetate (EtOAc) extract of A. dioicus showed excellent scavenging activity using DPPH and ABTS anti-oxidant analysis at the $1,000{\mu}g/mL$ concentration. While tyrosinase inhibitory effect was measure for whitening assay and showed 59.2%, the suppression levels of elastase and collagenase were 56% and 90% respectively for anti-wrinkle activity. Therefore, it is plausible to conclude that A. dioicus extract, especially EtOAc fraction which has outstanding whitening, anti-oxidant, and anti-wrinkle activities, could be used as a new functional materials for cosmetics.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.4
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• pp.155-161
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• 2020

PURPOSE: This study investigated the effect of a head-mounted display (HMD) based virtual reality (VR) cognitive rehabilitation program on the cognitive ability and activities of daily living in patients with mild cognitive impairment. METHODS: This study enrolled 5 mild cognitive impairment patients at the G welfare center in Gwangju metropolitan city. Patients were examined using the MMSEDS (Mini mental state examination-dementia screening). The VR cognitive rehabilitation program was applied twice a week for four weeks. The functional independence measure (FIM) and Loewenstein occupational therapy cognitive assessment-geriatric population (LOTCA-G) were compared before and after applying the VR cognitive rehabilitation program. RESULTS: Subsequent of application of the VR cognitive rehabilitation program, significant increase was observed in the LOTCA-G score. The FIM score was also perceived to increase, after the intervention, but was not statistically significant. CONCLUSION: Application of the VR cognitive rehabilitation program as a therapy is effective in improving the visual perception, and upper extremity executive ability, especially orientation, thinking organization, attention, and concentration.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.3
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• pp.105-112
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• 2011

More accurate evaluation of iodine consumption of Koreans can be made by measuring the urinary iodine excretion of people living in representative areas. The data about average iodine excretions by region, sex and age were gathered in order to suggest as a factor the criteria on the progress or prognosis of thyroid disease patients. This study was conducted on 3,000 subjects (2,000 Younggwang-gun residents and 1,000 Muan-gun residents) between July 2004 and August 2005. The data sampling was done based on stratified random sampling and the data were analyzed according to age (the subjects were divided into age groups, five years each) and sex of the subjects. Of the 3,000 subjects, a total of 1,592 people (1,174 in Younggwang-gun and 418 in Muan-gun) participated in this study, which used ISE (iodine ion selective electrode) to measure the concentration of iodine in urine. The 1,592 subjects are composed of 732 males and 860 females. The average urinary iodine excretion was $3.10{\pm}1.75mg/L$ (0.31~15.2 mg/L). The average iodine excretion of males was $3.09{\pm}1.61mg/L$ (0.42~15.2 mg/L) while it was $3.11{\pm}1.86mg/L$ (0.31~12.5 mg/L) among females, which represents no significant difference between males and females. However, the values were significantly higher than those of Europeans and Americans. There were statistically significant differences among the regions. When the data were analyzed according to age, females in their 40s were found to have a little less urinary iodine excretion and males had less and less iodine excretion as they get older. These results are deemed to have a statistically significant difference. This study was conducted on a large number of people (N=1,592) for the first time in Korea. If the data collected through this study can be regarded as the average urinary iodine excretion of Koreans, it is possible to conclude that the average iodine consumptions of Koreans are a lot more than Europeans and Americans. Thus, the effect of much iodine consumption should be studied further.

• International Journal of Highway Engineering
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• v.14 no.1
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• pp.55-61
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• 2012

The ability of clay mineral to remove non-point sources such as SS, COD, T-N. T-P in the urban runoff has been tested to develop the porous filter material. The diameter of 3mm ball type filters were made of clay minerals for the tests. The experiments were carried out to measure the concentration of non-point sources of contaminants with flow rate of effluents. The test results show that clay filter has good response to remove SS, COD comparing to those of activated carbon filter. Also the performance of the clay filter to remove T-N and T-P is almost the same when using the activated carbon filter.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.3
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• pp.563-571
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• 2006

The purpose of this study was to identify the effects of oriental herbal drink to improve aerobic capacity in elite endurance runners. 14 male elite college runners were participated and divided into two group; i ) oriental herbal drink group (OG), ii ) placebo group (PG). All subjects were completed treadmill exercise protocol using GXT at before (B) and after (A) experimental treatment of one week. The V02max, anaerobic threshold (AT) were measured by gas analysis and heart rate (HR) were measure by polar system at pre, max, post, post 30 min and post 60 min. Blood samples were collected to analyze blood components. The V02max were significantly increased in OGA compared to OGB whereas the V02max and AT in OGA were significantly higher than PGA. The blood lactate concentration were shown higher decrease rate in OGA compared to Doth OGB and PGA during recovery whereas LDH and Na were significantly increased in OGA compared to both OGB and PGA. The blood concentrations of CI and K were significantly increased in OGA compared to PGA. There were no significant differences were founded in WBC, RBC, Hct, Hb and other components associated with energy sources(glucose, TG, TC, HDL, LDL, creatinine, CPK). These results suggested that this oriental herbal drink can be administrated to improve aerobic capacity in long distance runners.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.199-199
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• 2011

Recently, Thin film transistors (TFTs) with amorphous oxide semiconductors (AOSs) can offer an important aspect for next generation displays with high mobility. Several oxide semiconductor such as ZnO, $SnO_2$ and InGaZnO have been extensively researched. Especially, as a well-known binary metal oxide, tin oxide ($SnO_2$), usually acts as n-type semiconductor with a wide band gap of 3.6eV. Over the past several decades intensive research activities have been conducted on $SnO_2$ in the bulk, thin film and nanostructure forms due to its interesting electrical properties making it a promising material for applications in solar cells, flat panel displays, and light emitting devices. But, its application to the active channel of TFTs have been limited due to the difficulties in controlling the electron density and n-type of operation with depletion mode. In this study, we fabricated staggered bottom-gate structure $SnO_2$-TFTs and patterned channel layer used a shadow mask. Then we compare to the performance intrinsic $SnO_2$-TFTs and doping hafnium $SnO_2$-TFTs. As a result, we suggest that can be control the defect formation of $SnO_2$-TFTs by doping hafnium. The hafnium element into the $SnO_2$ thin-films maybe acts to control the carrier concentration by suppressing carrier generation via oxygen vacancy formation. Furthermore, it can be also control the mobility. And bias stability of $SnO_2$-TFTs is improvement using doping hafnium. Enhancement of device stability was attributed to the reduced defect in channel layer or interface. In order to verify this effect, we employed to measure activation energy that can be explained by the thermal activation process of the subthreshold drain current.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.217-224
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• 2011

Removal of dissolved selenium by D. michiganensis, a iron-reducing bacterium, and effects of dissolved metal elements such as iron, sulfate, and copper were investigated. Selenide that was reduced from selenite (2 mM) by D. michiganensis was gradually removed from the aqueous medium. As the reduced selenide was combined with aqueous iron, it was precipitated as a nanoparticulate iron-selenide. Sulfate and copper negatively affected the microbial selenite reduction, and the copper was especially toxic to the bacterium, inhibiting a microbial removal of dissolved selenite. These results show that it should be carefully biotreated for a selenium-contaminated site considering in situ sulfate or copper distribution and concentration. Consequently, the formation of iron-selenide by bacteria will be an important measure for preventing a long-distance migration of selenium in the subsurface environments.