• Journal of Welding and Joining
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• 제14권5호
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• pp.134-144
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• 1996

A study was performed to investigate the properties of base metal and weldment for two HSLA steels and one HY-100 steel. Tensile, yield strength and elongation of HSLA-A steel were superior to those of HY-100 steel and yield ratios in HSLA-A and HSLA-B steels were higher than HY-100 steel owing to the precipitation of $\varepsilon$-Cu phase. The impact energy of HSLA-A steel was greater at all aging temperatures than that of HY-100 steel. HSLA-A and HY-100 steels had low impact transition temperature of about -l$25^{\circ}C$ and high upper shelf energy, The peak hardness of weldment in HSLA-A, HSLA-B and HY-100 steels were Hv 299, Hv 275 and Hv 441, respectively. The hardenability of HY-100 steel was largest due to the higher amount of carbon. The y-groove test showed that HSLA steels had superior resistance to cold cracking. Toughness of weld joint at the F. L. and F. L. ＋1mm in HSLA-A was almost the same as HY-100, but those at F. L.＋3mm and F. L.＋5mm was greater in HSLA-A steel.

• Journal of Welding and Joining
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• 제14권3호
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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.

• Journal of Welding and Joining
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• 제25권1호
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• pp.42-48
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• 2007

For high performance and structural stability, application of high strength steel has continuously increased. However, the change of the base metal gives rise to problems with the accuracy management of the welded structure. It is attributed to the martensite phase transformation of the high strength low alloy steel weldment. The purpose of this study is to establish the predictive equation of transverse shrinkage and residual stress for the HY-100 weldment. In order to do it, high speed quenching dilatometer tests were performed to define a coefficient of thermal expansion(CTE) at the heating and cooling stage of HY-100 with various cooling rates. Uncoupled thermal-mechanical finite element(FE) models with CTE were proposed to evaluate the effect of the martensite phase transformation on transverse shrinkage and residual stresses at the weldment. FEA results were verified by comparing with experimental results. Based on the results of extensive FEA and experiments, the predictive equation of transverse shrinkage and longitudinal shrinkage force at the HY-100 weldment were formulated as the function of welding heat input/in-plane rigidity and welding heat input respectively.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1996년도 특별강연 및 춘계학술발표 개요집
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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.

• 생명과학회지
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• 제11권1호
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• pp.76-82
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• 2001

Fifteen species of microorganisms were isolate form the intestines of fishes, fish feed, and ferment. Eleven microorganisms except HY4, HY8, HY12, and HY13 were Gram-positive, and HY1, HY2, HY3, HY5, HY6, and HY7 produced lactic acid. The species of HY1, HY2, HY3, HY4, HY5, HY6, HY13, and HY14 showed some growth in the medium containing 1% of NaCl. Except HY6, HY7, HY8, HY12 and HY5, 10 isolates had proteolytic activity, whereas only HY13 and HY14 had lipase activity. From all the results four isolates (HY3, HY4, HY13 and HY14) were chosen for the degradation of fish wastes. There was no mutual inhibition among the microorganisms, and the optimum temperature and pH for the growth of the mixed culture were found to be 3 2$\^{C}$ and 7, respectively. Under the optimum growth conditions the maximum optical density and the maximum specific growth rate were estimated to be 2.35 and {TEX}$0.46h^{-1}${/TEX}, respectively. Major microorganisms in the mixed culture at the log-phase were HY3 and HY4, which occupied 70%. The degrading efficiency of fish waste by the mixed microorganisms was 2.3 times higher, compared to control. The total amount of free amino acids in the degraded products from fish wastes was 39g/100g protein and little odor was produced by the mixed microorganisms after 48 hours.

• 생명과학회지
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• 제32권4호
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• pp.285-289
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• 2022

본 연구에서는 인천시 영흥도에서 채취한 해수시료에서 분리한 한천분해세균의 생육특성과 균주가 생산하는 agarase 특성을 분석하였다. 분리된 균주의 16S rRNA 유전자 염기서열은 Agarivorans 속 세균과 95% 유사하여, 분리된 균주를 Agarivorans sp. HY-1으로 명명하였다. Agarivorans sp. HY-1을 Marine broth 2216 배지에서 27℃, 250 rpm 조건으로 배양하니 생장은 1일차에, 효소활성은 2일차에 최대를 보였다. 조효소액은 균주 배양액에서 세포외로 분비되는 agarase로 준비하였다. Agarivorans sp. HY-1균주의 세포외 agarase는 40℃와 pH 7.0 (20 mM Tris- HCl)에서 최대의 활성을 보였다. 한천분해효소는 20, 30, 40, 50, 60 및 70℃에서 각 64, 91, 100, 97, 89 및 60%의 상대활성을 나타냈으며, pH 5, 6, 7 및 8에서는 79, 95, 100 및 55%의 활성을 나타냈다. 이 agarase는 20, 30, 40℃에서 2시간 열처리를 하였을 때 86% 이상의 잔존활성을 보였으며 50℃에서는 2시간 후 44% 이상의 잔존활성을 보였다. TLC 분석 결과, Agarivorans sp. HY-1는 α-agarase를 생산하는 것이 확인되었다. α-Agarase의 분해산물은 항암 활성 및 항산화 효과를 지니고 있으므로, Agarivorans sp. HY-1 균주와 agarase는 유용하게 이용할 수 있을 것으로 기대된다.

• 한국기후변화학회지
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• 제4권2호
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• pp.177-188
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• 2013

본 연구에서는 임상도와 HyTAG 모형을 적용하여 기후변화에 따른 경기도 용인시 임상의 잠재 생육적지 분포 변화와 산림 재적 및 탄소저장량 변화를 예측하였다. 이를 위해 제5차 임상도와 전국산림자원조사를 이용한 생장모델을 적용하여 현재의 용인시 산림재적을 예측하였다. HyTAG 모형을 적용하여 10년 단위로 미래 100년 후까지 잠재생육 적지 분포를 예측하고, 생장모델인 대수차 변형을 이용하여 산림 재적을 산출하였다. 용인시 산림을 제5차 임상도를 이용하여 분석한 결과, 현재 침엽수림 37.8%, 활엽수림 62.2%로 분포하고 있었다. HyTAG 모형을 적용한 30년 후 임상의 분포는 침엽수림 0.13%, 활엽수림 99.97%로 변화하였으며, 60년 후에 용인시 전체의 임상이 활엽수림으로 분포하는 것으로 나타났다. 또한, 현재 산림탄소량은 1,773,862 tC(56.79 tC/ha)로 측정되었으며 HyTAG 모형을 적용한 50년 후에 탄소저장량은 4,432,351 tC(141.90 tC/ha), 100년 후에는 6,884,063 tC(220.40 tC/ha)로 예측되었다. HyTAG 모형에 따른 수종별 변화를 분석해 본 결과, 잣나무, 낙엽송, 리기다소나무, 소나무는 각각 10년, 30년, 30년, 50년 이후에는 기후에 적합하지 않는 것으로 예측되었으며, 모두 참나무류가 적합한 것으로 예측되었다.

• International Journal of Oral Biology
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• 제38권4호
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• pp.169-173
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• 2013

HyPer is the genetically encoded biosensor of intracellular hydrogen peroxide ($H_2O_2$), the most stable of the reactive oxygen species (ROS) generated by living cells. HyPer has a high sensitivity and specificity for detecting intracellular $H_2O_2$ by confocal laser microscopy. However, it was not known whether high speed ratiometric imaging of $H_2O_2$ by HyPer is possible. We thus investigated the sensitivity of HyPer in detecting changes to the intracellular $H_2O_2$ levels in HEK293 and PC12 cells using a microfluorometer imaging system. Increase in the HyPer ratio were clearly evident on stimulations of more than $100{\mu}M$ $H_2O_2$ and fast changes in the HyPer ratio were observed on ratiometric fluorescent images after $H_2O_2$ treatment. These results suggest that HyPer is a potent biosensor of the fast temporal production of intracellular $H_2O_2$.

• Journal of Oral Medicine and Pain
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• 제10권1호
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• pp.17-31
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• 1985

Personality characteristics of TMJ dysfunction patients was studied by means of MMPI test. 100 TMJ dysfunction patients and 100 healthy controls were subjected at the Department of Oral Diagnosis and Oral Medicine, Pusan National University Hospital, during the period from March 1983 to February 1985. All the patients were divided into 2 groups namely, acute group and chronic group by duration of path and discomfort problems for 6 months or longer. The obtained results were as follows : 1. Mean value of T-scores on each clinical scale was within normal range in both patient and control group. 2. There was significant difference in scales of Hs, D. Hy, Pt, Sc and IR between patient and control group. 3. As compared with control group by sexual subclass, scales of Hs, Hy and Pt of both sex, scales of Sc and M-DI of male and scales of D of female in patient group were significantly higher than those in control group 4. The longer was duration of TMJ problems, i.e., in increasing order of control, acute and chronic group, the higher was mean value of T-scores on scales of Hs, D, Hy, Pt, Sc, IR and M-DI. 5. Mean values of T-scores on scales of Hs, D and Hy were the highest in all the clinical scales of total class and subclasses(i. e. male group, female group, acute group and chronic group) with TMJ dysfunction and showed 1-:i-2 (Hs, -Hy, -D. ) profile pattern, conversion "V.ot;V.

• Food Science and Biotechnology
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• 제15권5호
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• pp.677-682
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• 2006

Strain HY701 was isolated from human feces for probiotic use by selecting highly resistant isolates to artificial gastric acid and bile acid. Strain HY701 was identified as Lactobacillus reuteri using 16S rDNA sequencing, and tentatively named L. reuteri HY701. The resistance of L. reuteri HY701 to artificial gastric acid (PH 2.5) was high with a survival rate of over 90%. L. reuteri HY701 also showed high tolerance to artificial bile acid after incubation in artificial gastric acid. Using the API ZYM test kit, the carcinogenic enzymes (${\beta}$-glucuronidase and (${\beta}$-glucosidase were not detected with L. reuteri HY70l, while the beneficial enzyme (${\beta}$-galactosidase was weakly detected. L. reuteri HY701 was sensitive to $100\;{\mu}g/mL$ nisin, $20\;{\mu}g/mL$ roxithromycin, $15\;{\mu}g/mL$ erythromycin, but resistant to $20\;{\mu}g/mL$ streptomycin, $10\;{\mu}g/mL$ tetracycline, $20\;{\mu}g/mL$ ciprofloxacin, $20\;{\mu}g/mL$ nystatin, $20\;{\mu}g/mL$ gentamycin, $10\;{\mu}g/mL$ doxycycline, $10\;{\mu}g/mL$ chloramphenicol, and $20\;{\mu}g/mL$ ampicillin. L. reuteri HY701 was shown to possess bactericidal activity as it inhibited the growth of Listeria monocytogenes ATCC 19111 and Escherichia coli JM109 completely within 24 hr of incubation. These results indicate that L. reuteri HY701 could be used as a probiotic strain.