• Korea journal of population studies
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• v.23 no.2
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• pp.167-187
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• 2000

The rates and numbers of elderly suicide in Korea have been increased during 1985-1998. This indicates the seriousness of the problems which the elderly are faced with. So many late-life problems may push older people across the edges. Those in unbearable situations may call out fur helps, they may try to cope with various ways, or they may commit suicides. Because it is widely believed that suicide among the elderly can be understood as a personal solution or alternative to late-life problems in old age, the elderly\`s suicides seem to be an appropriate indicator in estimating seriousness of late-life problems. A comparison of the history of suicide research with other populations shows that the several late-life problems have been found with placing an individual elder at risks for increasing suicidal behaviors Research has identified such problems as financial insecurity, retirement, loss of social roles, physical illness, lack of social supports, and loneliness as the problems that increase the incidence of suicidal behavior. Though it is difficult far us to explain and understand the phenomenon of the elderly\`s suicide because of its complexity, we need to ascertain problems and social conditions behind suicides and also to prepare for some appropriate policy-tasks in light of social welfare for the aged, through examining the phenomenon. For explaining the elderly\`s suicide, the theoretical orientations are based on sociological perspectives in the paper. From the standpoints of social integration theory and exchange theory, this study is to examine the relationship between late-life problems and suicide. These two may have been fruitfully employed in conjunction with each other. Finally, this study would identify urgent late-life problems related with the elderly\`s suicide and suggest the relevant policies for Korean elders. Sometime in the near future, the government should be required to provide social welfare programs for the elderly, particularly for those at risk for increasing suicidal behaviors.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.9
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• pp.1351-1357
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• 2016

Green tea (Camellia sinensis) seed extract (GTSE) was prepared under various pretreatment conditions and used to investigate its extraction yield and anti-yeast activity. Anti-yeast activity of GTSE from seeds with or without the coats was the same, whereas the extraction yield was slightly higher in extract from seeds without the coat. Anti-yeast activity of GTSE from seeds with different water contents or particle sizes was the same, whereas the extraction yield was highest in extract from seeds with 7.3% moisture or a smaller particle size. Anti-yeast activity of defatted green tea seed extract (DGTSE) was the same as that of GTSE. Extraction yield was higher in DGTSE from defatted seeds by the oil press machine compared to hexane extraction. Defatted green tea seed (DGTS), a by-product from the oil extraction process, is a good natural source of anti-yeast preservative. The extraction yield and anti-yeast activity of DGTSE were investigated using various extraction solvents, temperatures, and times. The results show that water was an economic extraction solvent, and anti-yeast activity of DGTSE was unstable at $90^{\circ}C$. These results suggest that water, extraction temperature of $50^{\circ}C$, and extraction time of 4 h were the most efficient for extraction of anti-yeast compounds from DGTS.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.2
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• pp.212-218
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• 2006

Changes of paralytic shellfish poison (PSP) contents, toxicity and toxin composition with pH and storing periods at different temperature in toxic blue mussel, Mytilus edulis, were tested by using fluorometric HPLC method. Toxicity at pH 3 was the highest as 14.1 MU/g $(100\%)$ and showed 12.9 MU/g $(92.1\%)$ at pH 5, 9.0 MU/g $(63.8\%)$ at pH 7, 3.6 MU/g $(25.5\%)$ at pH 9 and 0.8 MU/g $(5.7\%)$ at pH 10 which suggested PSP was unstable at alkaline conditions. The decrease in toxicity during storage days was depend on pH and temperature. The toxicity markedly decreased until during the first S day storage $(19.9\~65.3\%)$ at all pH (3, 5, 7, 9) and temperature (30, 5, $-20^{\circ}C$), but, slightly decreased after then till to 30 days. C group toxin (C1 and C2) was the major components and other toxins such as GTX 1,2,3,4, STX and dcSTX were detected. Among the 8 toxins, GTX1,4, dcSTX and STX were firstly decreased according to the decreasing the toxicity at all processing conditions. The toxicity in blue mussel (14.1 MU/g) were able to remove by heating over 10 minutes at pH higher than 7.

• Tunnel and Underground Space
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• v.14 no.3
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• pp.167-174
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• 2004

This paper is to introduce an article published in Rock Mechanics and Rock Engineering, 2003. In this research, a fracture mechanics model is developed to illustrate the importance of time-dependence far brittle fractured rock. In particular a model is developed fer the time-dependent degradation of rock joint cohesion. Degradation of joint cohesion is modeled as the time-dependent breaking of intact patches or rock bridges along the joint surface. A fracture mechanics model is developed utilizing subcritical crack growth, which results in a closed-form solution for joint cohesion as a function of time. As an example, a rock block containing rock bridges subjected to plane sliding is analyzed. The cohesion is found to continually decrease, at first slowly and then more rapidly. At a particular value of time the cohesion reduces to value that results in slope instability. A second example is given where variations in some of the material parameters are assumed. A probabilistic slope analysis is conducted, and the probability of failure as a function of time is predicted. The probability of failure is found to increase with time, from an initial value of 5% to a value at 100 years of over 40%. These examples show the importance of being able to predict the time-dependent behavior of a rock mass containing discontinuities, even for relatively short-term rock structures.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.52.1-52.1
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• 2011

최근에 에너지 자원의 고갈이 다가오는 상황에서 태양전지 분야가 주목받고 있으며 이에 대한 시장이 급격하게 확대되고 있다. 그러나 현재의 태양전지는 주를 이루고있는 실리콘태양전지의 경우 원재료 수급이 불안정하여 가격 변동이 심하다. 따라서 이를 대체할 2세대 태양전지인 박막형 태양전지의 연구가 활발히 이루어지고 있다. 박막형 태양전지 중에서도 주목받고 있는 것은 Cu(In,Ga)$Se_2$(CIGS)박막 태양전지이다. CIGS는 Ga의 농도에 따라 1.02~1.68eV의 다양한 에너지 밴드갭을 갖는 직접천이형 반도체 물질이다. 또한 $1{\times}10^5cm^{-1}$의 높은 광흡수계수를 가지고 있으며, $450{\sim}590^{\circ}C$의 고온공정에서도 매우 안정하여 열화현상이 거의 보이지 않아 박막형 광흡수층 재료로서 적합하다. 흡수층을 제조하는 방법은 여러 가지가 있지만, 본 연구에서는 균일성이 뛰어나고 원료사용효율이 높은 sputtering 방법을 사용하였다. 그리고 결정화하기위해서 유독기체를 사용하는 셀.렌.화. (selenization) 방법 대신 전자빔을 조사하는 방법을 채택하였다. sputtering을 통한 CIGS precursor을 제조하기위해 2~3개의 화합물target을 사용하는데, 대표적인 방법으로 동시에 sputtering하는 co-sputtering 방법과 각각의 단일 층을 쌓아 제조하는 stack형으로 분류된다. 본 연구는 CIGS precursor를 제조하기 앞서 CuGa 단일 층만을 제조하여 공정조건에 따른 박막을 제조하였다. 제조된 CuGa 단일층은 전자빔 처리에 따른 영향을 알아보기 위해 전자빔의 세기와 공정시간을 달리하여 특성을 알아보았다. 실험에서는 Cu:75wt%,Ga:25wt% 조성의 target을 사용하여 공정 압력을 각각 10~1mTorr로 변화시키며 실험을 실시하였으며 공정 power는 50W, 70W, 100W로 변화 시키며 실험을 실시하였다. 이때 실험의 초기진공은 turbo-molecular pump를 이용하여 $1{\times}10^{-6}torr$ 이하로 하였으며, Target과 기판사이의 거리는 모두 같은 조건으로 고정하여 실험을 실시하였다. 박막의 균일성을 증가시키기 위하여 5 rpm의 속도로 기판을 회전하였으며 기판 온도는 가열하지 않고 상온에서 전구체를 증착하였다. 그 후 전자빔의 세기를 고정 시킨 후 전자빔 조사 시간을 조절하여 전자빔 조사 전후의 특성을 각각 분석하였다. 전기적특성은 Hall effect, 4-point probe, 구조적 특성은 SEM,EDS, XRD, XRF 를 이용하여 분석하였다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.6
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• pp.520-528
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• 1987

Quality stability of roasted lavers during heat treatment and storage was investigated measuring the changes in pigments including chlorophyll a, carotenoids and biliproteins, fatty acids and free amino acids as the major quality factors. In roasting of fried lavers, carotenoids were found to lie more stable than chlorophyll a, and biliproteins were most heat labile. The overall heat stability of the pigments depended upon heating time and temperature. Chlorophyll a and carotenoids were retained more than $90\%$ in the casts of roasting for 90 min. at $60^{\circ}C;\;60min.\;at\;80^{\circ}C;\;10\;min.\;at\;100^{\circ}C;\;or\;5min.\;at\;150^{\circ}C$ while biliproteins remained about $70\%$. The lipids of dried lavers including polyunsaturated fatty acids appeared rather heat stable when compared to the stability of pigments under the same conditions of roasting. Spray of sesame oil or seasoning solutions on the surface of lavers after roasting seemed desirable for stabilizing pigments and free amino acids during storage particularly at low water activity. And that was also benefit for the protection of polyenoic fatty acids from rapid progress of oxidation during storage. Free amino acids were reduced fast during roasting, especially most of threonine and glycine while glutamic acid was rapidly lost during the storage.

• Journal of the Korean Geosynthetics Society
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• v.12 no.3
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• pp.43-53
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• 2013

In this study, an analysis about the causes of different types of excavation on accidents is required in order to prevent the frequently occurring accidents related to the earth retaining structure and excavation. Also, analysis of influence was performed by using numerical typical soil conditions and construction trend using numerical analysis method. According to the analysis results of 25 accident cases, the main influence factors were found as following: insufficient of soil survey, instability of temporary facility and lack of groundwater treatment, etc. Furthermore, in the numerical analysis result of 22 cases, drainage method was occurred larger settlement than waterproof method in the Inland. In case of applying the earth anchor method, it needs more detailed in the regions, which are discovered soft ground or rock discontinuities. Also, The consolidated clay absolutely needs further consideration of excess hydrostatic pressure.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.3
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• pp.227-236
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• 2014

In this study, O/W and W/S emulsions were prepared by combining oils having different required hydrophilic lipophilic balance (HLB) values under the diverse conditions of HLB values composed of a hydrophilic surfactant and a lipophilic surfactant and their stability was investigated. Results showed that the higher the viscosity of O/W emulsions was as the lower the HLB value of emulsifier and emulsion particle showed a tendency to be a smaller and compact and stabler in centrifugal filtration. W/S emulsions also showed a similar tendency to be a smaller and compact as HLB values of emulsifier was higher and stabler in centrifugal filtration. However, the viscosity of W/S emulsion tended to get lower in HLB conditions of all emulsifiers as the time passed. This indicated that the emulsions had an unstable feature in long-term stability. In conclusion, the results showed opposite to the known theory that O/W emulsion is proper to be applied by nonionic surfactant with a high HLB value and W/S emulsion to be applied by nonionic surfactant with a low HLB value and provide useful information for the cosmetics research and related areas.

• Korean Journal of Food Science and Technology
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• v.33 no.6
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• pp.664-668
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• 2001

The physical and chemical stabilities of carthamin of red pigment from safflower petals were investigated at various conditions of pHs, temperatures, inorganic ions, sugars, light and polysaccharides. The half-life values at pH 3.0, 5.0, 9.0 and 11.0 were 5.3, 5.0, 11.0 and 45.0 h, respectively, at $25^{\circ}C$. Therefore, carthamin is unstable at acidic condition. Carthamin was red, orange and yellow at acidic, neutral and alkaline solutions, respectively. At pH 3.0, carthamin was thermally unstable and the half lives were 3.62, 9.05 and 48.2min at $90^{\circ}C$, $70^{\circ}C$ and $50^{\circ}C$, respectively. Among various inorganic ions, $Al^{3+}$ stabilized carthamin at acidic condition. At pH 5.0, carboxymethylcellulose prolonged the half-lives of carthamin at $25{\sim}90^{\circ}C$. Carthamin was very sensitive to light (20,000 lux) and the half-life was 2.32 min at pH 3.0.

• Journal of the Korean association of regional geographers
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• v.7 no.1
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• pp.21-34
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• 2001

Summarized results of this study that examined the characteristics of farm household in suburban areas classified by the fanning types are as follows. When it was looked into with the side of farm household and his family, the type of the farm household in suburban areas are related to the quality of fanning labor rather than the quantity of it. Regardless of the type of the farm household, it depends upon the family labor (usually men and wives). And the age of farm manager is an important part in the quality of fanning labor. The size of the farm household is related to the individual fanning labor. The size of self-sufficient crops(mainly rice) farm household will be small as the farmer gets to be old. But the size of commercial crops farm household has less tendency to change in terms with the age of farm manager. The fanning commercialism takes an important part in the maintenance and development of suburban agricultural areas. But, in fact, there is a shortage of farming labor. So the physical condition of farmland is the most important part in agricultural durability. After this study, we can conclude that we won't have enough chance to solve the problem of family member separation and shortage of fanning labor even though it is in the suburban area or in the profitable farm until we give them more enough chance to get a job(except fanning) and the better education infrastructure. To make matters worse, the aggravation of farm house-hold's economy due to unstable price of farming products' threatens the agricultural durability. Consequently, in order to get a development of agriculture and rural community, a qualitative change with improvement of agricultural conditions and of products distribution system is needed.