• Journal of Welding and Joining
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• v.14 no.5
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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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• 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.

• Journal of Welding and Joining
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• v.25 no.1
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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.

• 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 Life Science
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• v.11 no.1
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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.

• Journal of Life Science
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• v.32 no.4
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• pp.285-289
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• 2022

In this study, the growth characteristics of an agar-degrading bacterium isolated from seawater samples collected from Yeongheungdo, Incheon, and the characteristics of its agarase were analyzed. The 16S rRNA gene sequence of the isolated strain was 95% similar to that of the genus Agarivorans, and thus the isolated strain was named Agarivorans sp. HY-1. When Agarivorans sp. HY-1 was cultured in a marine broth 2216 medium at 27℃ and 250 rpm, it showed maximum growth on day 1 and showed maximum enzymatic activity on day 2. A crude enzyme solution was prepared from secreted agarase in the culture medium. The extracellular agarase of the Agarivorans sp. HY-1 strain showed maximal activity at 40℃ and pH 7.0 (20 mM Tris-HCl) with 591.91 U/l. The agarase exhibited relative activities of 64, 91, 100, 97, 89, and 60% at 20, 30, 40, 50, 60, and 70℃, respectively. At pH 5, 6, 7, and 8, the relative activities were 79, 95, 100, and 55%, respectively. Furthermore, the agarase exhibited >86% residual activity at 20, 30, and 40℃ for 2 hr and >44% residual activity at 50℃ after 2 hr. A TLC analysis confirmed that Agarivorans sp. HY-1 produced α-agarase. As the degradation products of α-agarase have anticancer and antioxidant effects, Agarivorans sp. HY-1 and its agarase may well prove useful.

• Journal of Climate Change Research
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• v.4 no.2
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• pp.177-188
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• 2013

In this research, forest cover distribution change, forest volume and carbon stock in Yongin-city, Gyeonggi procince were estimated focused on the forest of Yongin-City using forest type map and HyTAG model in relation to climate change. Present forest volume of Yongin-city was estimated using the data from $5^{th}$ Forest Type Map and Korean National Forest Inventory (NFI). And for the future 100 years potential forest distribution by 10-year interval were estimated using HyTAG model. Forest volume was also calculated using algebraic differences form of the growth model. According to the $5^{th}$ Forest Type Map, present needleleaf forest occupied 37.8% and broadleaf forest 62.2% of forest area. And the forest cover distribution after 30 years would be changed to 0.13% of needleleaf forest and 99.97% of broadleaf forest. Finally, 60 years later, whole forest of Yongin-city would be covered by broad-leaf forest. Also the current forest carbon stocks was measured 1,773,862 tC(56.79 tC/ha) and future carbon stocks after 50 years was predicted to 4,432,351 tC(141.90 tC/ha) by HyTAG model. The carbon stocks after 100 years later was 6,884,063 tC (220.40 tC/ha). According to the HyTAG model prediction, Pinus koraiensis, Larix kaempferi, Pinus rigida, and Pinus densiflora are not suitable to the future climate of 10-year, 30-year, 30-year, and 50-year later respectively. All Quercus spp. was predicted to be suitable to the future climate.

• International Journal of Oral Biology
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• v.38 no.4
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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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• v.10 no.1
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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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• v.15 no.5
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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.