• 열처리공학회지
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• 제5권1호
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• pp.13-22
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• 1992

The thermal stability of duplex high Mn-steel structure have been investigated using 15%Mn~1.0~2.4%C steels which are composed of ${\gamma}$-and ${\theta}$-phases in the range of temperature from 900 to $1100^{\circ}C$, and time from 50 to 300h. The results are as follows ; 1) The grain growth in single-phase region proceeds by grain boundary migration and the relation between mean radius $\bar{r}$ and annealing time t is described as follows ; $\bar{r}^2-{\bar{r}_0}^2=k_0{\cdot}t$ 2) The grain growth of duplex, (${\gamma}+{\theta}$), strucrure is slower than that single phase because the chemical composition of ${\gamma}$-and ${\theta}$-phases differs esch others. 3) The grain of (${\gamma}+{\theta}$) duplex structure grow slowly in a mode of Ostwald ripening. Because grain boundaries of ${\gamma}$-phase migrate under a restriction of pinning by ${\theta}$-phases. 4) In the duplex structures. the dispersed structures change to the dual-structures, as the volume fraction of the dispersed second-phase increase. Consequently, the growth-law, which is controlled by boundary-diffusion change to that of the volume diffusion-mechanism.

• Journal of Plant Biology
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• 제36권3호
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• pp.219-224
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• 1993

The effects of environmental factors on the growth of Enteromorpha compressa germlings from Daeyulri (34$^{\circ}$36'N; 127$^{\circ}$47'E), the southern cost of Korea were examined in laboratory culture through combinations of irradiance and salinity and temperature and salinity. They showed a maximum growth rate at 125 $\mu$E.m-2.s-1 and 32$\textperthousand$ of irradiance and salinity combination, and at 15$^{\circ}C$ and 32% of temperature and salinity combination. Optimal parameters for the growth of germlings were 15$^{\circ}C$, 125 $\mu$E.m-2s-1 and 32$\textperthousand$. The germlings of E. compressa were survived in a wide range of irradiance, temperature and salinity levels, even though they had relatively low irradiance optimum. In the field E. compressa occurred commonly during autumn and spring seasons and disappeared in summer, except for particular habitats. This may be caused by the salinity and water temperature of this area rarely drop below 26$\textperthousand$ and 8$^{\circ}C$ during winter. A broad tolerance to environmental and rapid growth of germlings made them a wide geographical distribution over the world and a survival in both the upper and lower intertidal zones.

• 한국미생물·생명공학회지
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• 제20권3호
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• pp.249-256
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• 1992

국내에서 구입 가능한 주요 식이 소재로부터 장내의 대표적인 유해균인 Clostridium perfringens의 생육을 억제시키는 소재를 탐색한 결과 감자즙에서 강력한 항균활성을 발견하였다. 감자즙 중 70% 황산암모늄용액에서 침전되는 단백질성 물질이 항균활성을 나타낸 것으로 밝혀졌으며, 이 감자단백질은 pH 4~10 사이에서는 안정하나 $60^{\circ}C$에서 10분간의 열처리로 그 활성이 소실되었다.

• 한국환경보건학회지
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• 제33권3호
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• pp.190-194
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• 2007

Aflatoxin $B_1$ is a mycotoxin produced by Aspergillus flavus and A. parasiticus and is a human carcinogen. This study was performed to investigate reduction of growth and aflatoxin production of A. parasiticus by kimchi. A. parasiticus was grown in a modified APT broth with the juice of kimchi (at a concentration of 7%) at $28^{\circ}C$ for 9 days. Aflatoxin $B_1$ was determined by use of high performance liquid chromatography (HPLC). The addition of the juice of kimchi significantly reduced mycelial growth and aflatoxin production during the incubation period (p<0.05). Reduction of mycelial growth of A. parasiticus as the result of addition of the juice of kimchi was observed to range between 64.8 to 83.4% while reduction of aflatoxin production ranged from 62.2 to 73.0%. This study indicates that kimchi could be an effective inhibitor of aflatoxin production although mycelial growth may be permitted. More research is needed to study the inhibitory effects of the metabolites of kimchi.

• 한국균학회지
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• 제37권2호
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• pp.173-180
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• 2009

This study was carried out to obtain basic data on mycelial growth characteristics for an artificial cultivation of Volvariella volvacea. Twelve URP primers were used to assess genetic relationship of V. volvacea and its result was divided into two groups. But there was nothing different in morphological characteristics in V. volvacea. Among five kinds of mushroom media, MCM medium was selected as the favorable culture medium. The optimal range of temperature and pH for mycelial growth on V. volvacea were 35oC and pH 6~8, respectively. Carbon sources had not an effect on 10 strains of V. volvacea, and nitrogen source for the optimum mycelial growth was yeast extract. Also, we selected GMVV 79004 as a superior strain of 10 strains V. volvacea based on the mycelial growth and yield.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.735-738
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• 2000

This paper shows experimentally that oxide layer on the p-type Si-substrate can grow at low temperature(500$^{\circ}C$∼600$^{\circ}C$) using high pressure water vapor system. As the result of experiment, oxide layer growth rate is about 0.19${\AA}$/min at 500$^{\circ}C$, 0.43${\AA}$/min at 550$^{\circ}C$, 1.2${\AA}$/min at 600$^{\circ}C$ respectively. So, we know oxide layer growth follows reaction-controlled mechanism in given temperature range. Consequently, granting that oxide layer growth rate increases linearly to temperature over 600$^{\circ}C$, we can expect oxide growth rate is 5.2${\AA}$/min at 1000$^{\circ}C$. High pressure oxidation of silicon is particularly attractive for the thick oxidation of power MOSFET, because thermal oxide layers can grow at relatively low temperature in run times comparable to typical high-temperature, 1 atm conditions. For higher-temperature, high-pressure oxidation, the oxidation time is reduced significantly

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.301-306
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• 2002

The characteristics of parameters for the probability distribution of fatigue crack growth lives by the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length - the number of cycles curves are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratio of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth lives seems to follow the 3-parameter Wiubull and shows a slight dependence on specimen thickness and stress intensity level. The shape parameter, ${\alpha}$, does not show the dependency of thickness and stress intensity level, but the scale parameter, ${\beta}$, and location parameter, ${\upsilon}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.281.1-281.1
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• 2013

Shape control of gold nanocrystal is still one of the most important challenges remaining to achieve geometry dependent properties. Thus far, several strategies have been developed to control the shape of nanoparticles, such as adding capping agents and diverse additives or adjusting the temperature and pH. Here, we used an already established seed-mediated method that allowed us to focus on controlling the growth stage. Cetyltrimethylammonium bromide (CTAB) and ascorbic acid (AA) were used as the ligand and the reducing agent, respectively, without using any additional additives during the growth stage. We investigated how the relative ratio of CTAB and AA concentrations could be a major determinant of nanoparticle shape over a wide concentration range of CTAB and AA. As a result, a morphology diagram was constructed experimentally that covered the growth conditions of rods, cuboctahedra, cubes, and rhombic dodecahedra. The trends in the morphology diagram emphasize the importance of the interplay between CTAB and AA. Furthermore, high-index faceted gold nanocrystal was obtained by two step seeded growth. Already synthesized cubic particles developed into hexoctahedral nanocrystal consisting of 48 identical {321} facets, which indicates that the growth of gold nanocrystal is affected by initial morphology of seed particles. The hexoctahedral gold nanoparticles can be used in catalysis and optical applications which exploiting their unique geometry. Our research can provide useful guidelines for designing various facetted geometries.

• Journal of Welding and Joining
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• 제20권1호
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• pp.97-102
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• 2002

The growth kinetics of intermetallic compound layers formed between the eutectic Sn-3.5Ag solder and the Cu and Ni/Cu pad by solid stateisothermal aging were examined. The interfacial reaction between the eutectic Sn-3.5Ag solder and the Cu and Ni/Cu pad was investigated at 70, 120, 150, $170^{\circ}C$ for various times. The intermetallic compound layer was composed of two phase: $Cu_6Sn_5$(${\varepsilon}-phase$) adjacent to the solder and $Cu_6Sn_5$(${\varepsilon}-phase$) adjacent to the copper and on solder/Ni pad the intermetallic compound layer was $Ni_3Sn_4$. Because the values of time exponent(n) have approximately 0.5, the layer growth of the intermetallic compound was mainly controlled by volume diffusion over the temperature range studied. The apparent activation energy for layer growth of total Cu-Sn($Cu_6Sn_5 + Cu_6Sn$), $Cu_6Sn_5$, $Cu_3Sn$ and $Ni_3Sn_4$ intermetallic compound were 64.82kJ/mol, 48.53kJ/mol, 89.06kJ/mol and 71.08kJ/mol, respectively.

• 한국정밀공학회지
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• 제8권2호
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• pp.27-35
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• 1991

We propose the crack growth rate equation which applied over three regions (threshold region, stable region, unstable region) of fatigue crack propagation. Constant stress amplitude fatigue tests are conducted for four materials under three stress ratios of R=0.05, R=0.2 and R=0.4. Materials which have different mechanical properties i.e. stainless steel, low carbon steel, medium carbon steel and aluminum alloy are used. The fatigue crack growth rate equation is given by $da/dN={\beta} (1-R)^{\delta}\({\DELTA}K-{\DELTA}K_t)^{\alpha} / (K_{cf}-K_{max})$${\alpha}, {\beta}$ , and ${\delta}$ are constants, and ${\Delta}K_t$ is stress intensity factor range at low ${\Delta}K$ region. The constants are obtained from nonlinear least square method. $K_{ef}$is critical fatigue stress intensity factor. The relation between half crack length and number of cycles obtained by integrating the crack growth rate equation is in agreement with the experimental data. It is also experimented with constant maximum stress and decreasing stress ratios, and the fatigue growth rate of each material is in accord with the proposed equation.