• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.253-253
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• 2016

최근 세계적으로 대체 에너지는 중요한 이슈가 되고 있으며 그 중 열전 재료는 유망한 에너지 기술로서 주목 받고 있다. 특히 고 직접화 전자 소자의 발열 문제를 해결하기 위해, 소형화와 정밀 온도 제어가 가능한 박막형 열전 소자에 연구가 주목 받고 있다. 박막형 열전소자 중 산화물 반도체계에 대한 연구가 활발히 진행되고 있으며, 이러한 산화물 반도체계 중 In2O3는 BiTe, PbTe 등의 기존의 재료에 비해 독성이 낮을 뿐만 아니라 내 산화성 및 고온에서 열적 안정성이 우수하여 고온에서 적용 불가능한 금속계 열전 재료의 한계를 극복 할 수 있다는 장점을 가진다. 우수한 성능 가장 낮은 캐리어 밀도를 가지기 때문에 의 열전 재료는 높은 전기 전도도 및 제백 계수 그리고 낮은 열전도도 특성을 가져야만 한다. IZO:Sn(Zn 10 wt.%, Sn 800 ppm) 박막의 경우, 높은 전기 전도성을 가지면서 비정질 구조를 가진다. 이와 같이 비정질 구조를 가지는 박막 열전 재료는 격자에 의한 열 전도도가 낮기 때문에 결정질 구조에 비해 전체 열 전도도 값이 낮을 것으로 기대된다. 따라서 높은 전기 전도도를 가지면서 동시에 낮은 열 전도도를 가지게 되어 우수한 열전 특성을 가질 것이라 예상된다. 이러한 특성을 바탕으로 본 연구에서는 비정질 구조를 갖는 Zn와 미량의 Sn을 동시에 첨가한 In2O3박막의 전기적 특성및 열전 특성을 관찰하고자 한다. 본 연구에서는 magnetron sputtering법으로 IZO:Sn(Zn 10 wt.%, Sn 800 ppm) 타깃을 이용하여 기판 가열없이 DC Power 70 W, 작업 압력 0.7 Pa으로 SiO2 기판 위에 $400{\pm}20nm$ 두께의 박막을 증착하였다. 이러한 공정으로 만들어진 박막은 대기 중 후 열처리를 각각의 200, 300, 400, 500, $600^{\circ}C$ 온도에서 진행하였다. 박막의 미세 구조는 XRD를 통해 관찰하였다. 그리고 박막의 전기적 특성은 Hall effect measurement을 통해 측정하였고, 열전 특성은 Seebeck 상수의 측정을 통하여 평가하였다. XRD 확인 결과 RT에서 증착한 박막과 후 열처리 200, 300, 400, $500^{\circ}C$ 결과 비정질 구조를 보였고, 후열처리 $600^{\circ}C$에서는 결정의 회절 피크를 보였다. 전기적 특성의 경우, 후 열처리 온도가 증가함에 따라 전기 전도도는 감소한다. 이는 공기중의 산소가 박막에 침투하여 oxygen vacancy를 막아 캐리어 밀도가 감소한것에 기인 된 것으로 판단된다. 열전 특성의 경우 제백상수는 후 열처리 $600^{\circ}C$에서 가장 높은 제백상수를 나타낸다. 제백 상수는 수식에 따라 캐리어 밀도의 -2/3승에 비례하게 된다. 수식에 따라 후 열처리 $600^{\circ}C$에서 가장 낮은 캐리어 밀도를 가지기 때문에 가장 높은 제백 상수를 가지게 된다. 열전 성능 척도인 Power factor는 제백 상수의 제곱과 전기전도도의 곱으로 나타내는데, 후 열처리 $200^{\circ}C$에서 가장 높은 Power factor를 보인다. 이는 캐리어 밀도 감소에 따라 전기 전도도는 감소하였지만 이로 인해 제백상수는 증가하였고, 또한 캐리어 밀도 감소에 따라 이온화 불순물 산란의 감소에 의해 이동도의 증가에 의한 것으로 판단된다. 박막의 경우 기판의 영향으로 인해 열 전도도 측정이 어려워 열전 성능 지수(ZT)를 계산을 할 수 없지만, 마그네트론 스퍼터링법으로 증착한 IZO:Sn 박막은 비정질 구조를 가지므로 격자진동에 의한 열 전도도가 낮아 전체 열 전도도가 결정질에 비해 낮을 것이며 이는 높은 열전 성능 지수를 가질 것으로 예상된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.188.1-188.1
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• 2015

For present investigation Fe/MgO/Fe/Co multilayer stack is grown on Si substrate using e-beam evaporation in ultrahigh vacuum. This stack is irradiated perpendicularly by 120 MeV $Ag^{8+}$ at different fluences ranging from $1{\times}10^{11}$ to $1{\times}10^{13}ions/cm^2$ in high vacuum using 15UD Pelletron Accelerator at Inter University Accelerator Centre, New Delhi. Magnetic measurements carried out on pre and post irradiated stacks show significant changes in the shape of perpendicular hysteresis which is relevant with previous observation of re-orientation of magnetic moment along the direction of ion trajectory. However increase in plane squareness may be due to the modification of interface structure of stacks. X-ray reflectivity measurements show onset of interface roughness and interface mixing. X-ray diffraction measurements carried out using synchrotron radiation shows amorphous nature of MgO and Co layer in the stack. Peak corresponding body centered Fe [JCPDS-06-0696] is observed in X-ray diffraction pattern of pre and post irradiated stacks. Peak broadening shows granular nature of Fe layer. Estimated crystallite size is $22{\pm}1nm$ for pre-irradiated stack. Crystallite size first increases with irradiation then decreases. Structural quality of these stacks was further studied using transmission electron microscopic measurements. Thickness from these measurements are 54, 36, 23, 58 and 3 nm respectively for MgO, Fe, MgO, Fe+Co and Au layers in the stack. These measurements envisage poor crystallinity of different layers. Interfaces are not clear which indicate mixing at interface. With increase fluence mixing and diffusion was increased in the stack. X-ray absorption spectroscopic measurements carried out on these stacks show changes of Fe valence state after irradiation along with change of O(2p)-metal (3d) hybridized state. Valence state change predicts oxide formation at interface which causes enhanced in-plane magnetization.

• The Journal of the Korean dental association
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• v.55 no.2
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• pp.156-164
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• 2017

Purpose: The aim of this in vitro study was to assess changes in remineralization by stimulated human saliva over a short period of 48 hours with quantitative light-induced fluorescence (QLF) technology. Materials and Methods: Bovine incisor surfaces were demineralized for 10 days. Two types of stimulated saliva were collected from 7 healthy persons. 24 hours after tooth brushing (Stimulated saliva group) and immediately after tooth brushing with 1,000 ppm NaF dentifrice (Dentifrice saliva group). The specimens were immersed in saliva and fluorescence images were obtained by QLF-digital (QLF-D $biluminator^{TM}$,) at 2, 4, 6, 12, 24, and 48 hours fluorescence loss (${\Delta}F%$) of the lesions. A paired t-test was performed to assess fluorescence differences between before (${\Delta}F_{baseline}$) and after (${\Delta}F_{treatment\;time}$) the remineralization process. Results: Before the remineralization, the mean ${\Delta}F_{baseline}$ of the initial demineralized specimens was $-18.42{\pm}0.15$ (%). In both groups, the ${\Delta}F$ values obtained at baseline and after 2 hours were statistically significant (P < 0.001), indicating recovery of the lesions by approximately 40% after 2 hours. After 48 hours, remineralization rates were slightly higher (49%) for the stimulated saliva group than for the dentifrice saliva group (41%), but the difference was not statistically significant. Conclusions: With QLF minute degrees of remineralization by saliva can be measured in periods as short as 2 hours. Additionally no significantly higher effects of remineralization were observed in the dentifrice saliva group when compared to the stimulated saliva group.

• KSBB Journal
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• v.14 no.2
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• pp.153-159
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• 1999

Fifteen microbes have been isolated from Jangja pond in Kuri-Si, Kyeonggi-Do. Among them, two strains showed excellent COD removal from wastewater, which were named Pseudomonas sp. BLP2052 and Flavobacterium sp. BLP20515, respectively. Optimal pH and temperature for the cell growth were 7.0 and $30^{\circ}C$ for both strains. Pseudomonas sp. BLP2052 and Flavobacterium sp. BLP20515 was applied to the reactor to treat wastewater and 66.0% and 65.7% COD (chemical oxygen demand) removal was achieved, respectively. Comparing these results to the case of applying mixed microbes present in Jangja pond, COD removal rate was 15% less. But when adding the selected microbes to the wastewater containing mixed microbes, COD removal rate increased by 5%. After 84 hour operation, we achieved 85.6% COD removal. When inhibitors were added less than 100 ppm, during the microbial wastewater treatment, Fe, Zn, Al, phenol and Cr influenced microbial activity more deterioratively in order. In the case of over 300 pm, Cr, Fe, Zn, Al and phenol showed severe deteriorative effect in order.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1641-1645
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• 2004

The purpose of this research is to investigate Chinese's preference and directions for improvement of Kimchi by sensory evaluation, and utilize Kimchi for the China eating habit by survey. Self administered questionnaires were collected 149 Chinese (16~25 yr) residing in Shanghai. About 89.9% of all the participants had eaten Kimchi before the survey. Overall preference about Kimchi was 3.59$\pm$0.62 (5 point: Lickertis scale) and affecting factors for overall preference were taste, appearance, texture, in that order. Chinese answered that tough texture (24.9%), spicy taste (20.5%) and fermented odor (18.1%) were the most important factors in improved quality of Kimchi. They answered that applications of Kimchi with Chinese cuisine are 'side dish with meat cuisine', 'eat with cooked rice, rice-mixed-in-soup, gruel' and 'use ingredients of cook', as similar to Korean's.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.171-177
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• 2014

In an effort to investigate special distribution of glucose content of potato tuber of a cultivar 'Superior' after harvest, a whole tuber was longitudinally cut into halves and cut-surface was divided into 11 regions. Approximate glucose concentration of each section was determined using a commercial blood glucose meter. Higher level of glucose was detected in the outer layers of tissue than inner part of tuber although there were lower coefficients of variation value, 37.4% and 34.1% among individual tubers and among defined sections, respectively. A positive correlation between the whole tuber and individual section was existed in glucose content, where the central pith tissue gave the highest coefficient (r = 0.921) and bud end tissue did the lowest (r = 0.544). Glucose content of the tubers stored for 4 months at $2.0^{\circ}C$ was 5.5 fold higher compared to the tubers kept in ambient temperature. The chip color of the former tubers was much brighter than those of the latter tubers. The result obtained in the present study suggests that the blood glucose meter can be used to a rapid and simple evaluation of glucose content and therein be applied to estimate the processing quality of potato tubers during postharvest handling.

• Nutrition Research and Practice
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• v.9 no.4
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• pp.433-438
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• 2015

BACKGROUND/OBJECTIVES: Breast milk is the best available food for optimum growth and development of infants and the breastfeeding rate is increasing in Korea. The purpose of this study is to measure the concentrations of macronutrients and to evaluate their changes according to lactation period in breast milk from lactating Korean women. SUBJECTS/METHODS: Milk samples were obtained from 2,632 healthy lactating women (mean age; $32.0{\pm}3.3years$), where the lactating period was up to a period of 8 months, who also volunteered to participate in the Human Milk Macronutrient Analysis Research. Lactose, protein, fat and water content in the breast milk samples were analyzed with infrared spectrometry using MilkoScan FT-2. RESULTS: The mean macronutrient composition per 100 mL of mature breast milk was 7.1 g for lactose, 1.4 g for protein and 3.0 g for fat, and energy content was 61.1 kcal. The protein concentration was significantly lower in milk samples at 1-2 weeks (2.0 g/dL) to 2-3 months (1.4 g/dL) than those at 0-1 week (2.2 g/dL), but it was similar among samples from 3-4 months to 7-8 months (1.3 g/dL). Mean lipid levels varied among different lactational period groups (2.7-3.2 g/dL), but presented no significant difference. Lactose concentration in the milk samples did not differ with lactation period. Maternal body mass index was positively related to protein and lipid breast milk contents, but was negatively related to lactose content. General linear models examining the associations between maternal variables and milk macronutrient content revealed that lactation period had a major impact on protein and lipid, but not on lactose content in breast milk. CONCLUSIONS: These results warrant future studies to explore factors that may be associated with changes in macronutrient content in human milk.

• Journal of Acupuncture Research
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• v.29 no.5
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• pp.187-195
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• 2012

Objectives : Amyotrophic lateral sclerosis(ALS) is a progressive and incurable disease that causes degeneration of the motor neurons of the brain stem and spinal cord. The purpose of this study was to report the effectiveness of Sa-am acupuncture treatment on ALS patient. Methods : Following the stabilization period, a ALS patient respiratory figures(Et $C_{O2}$, Sp $_{O2}$, RR, pulse) were measured by using capnography & pulse oximetry for 30 minutes before acupuncture treatment. Acupuncture treatment such as lung tonification($SP_3(+){\cdot}LU_9(+){\cdot}HT_8(-){\cdot}LU_{10}(-)$), heart tonification($HT_9(+){\cdot}LR_1(+){\cdot}SI_8(-){\cdot}KI_{10}(-)$), liver tonification ($KI_{10}(+){\cdot}LR_8(+){\cdot}LU_8(-){\cdot}LR_4(-)$) were conducted for 5 days. Each Sa-am acupuncture treatment conducted at AM 7 : 00, AM 11 : 00, PM 4 : 30 of the day. During acupuncture treatment, the patient respiratory figures were measured equally for 30 minutes. The patient was treated by using Dong-bang acupuncture needles($0.30{\times}4.0$) and also stimulated using infra red. Results : The value of Et $C_{O2}$ has decreased more after Sa-am acupuncture lung tonification treatment than others. The value of pulse has decreased more after Sa-am acupuncture heart tonification treatment than others. The value of raspiration rate has decreased more after Sa-am acupuncture liver tonification treatment than others. And the value of Sp $O_2$ has increased more after Sa-am acupuncture liver tonification treatment than others. Conclusions : Although this study was subject to a few limitations, but it shows that Sa-am acupuncture treatment for ALS patients has a meaningful effect. This study needs to be developed further using a larger sample size to obtain more valuable and meaningful data.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.248-258
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• 1979

Glucose 6-phosphate dehydrogenase of Leuconostoc mesenteroides which was purifid by an affinity chromatography was studied on the characterization, kinetics and chemical modification. The apparent molecular weight of the enzyme was 112,000 by the gel filtration method of Sephadex G-200 column. The optimum temperature of $NAD^+$-linked reation was 50$^{circ}C$ and the activation energy and the heat of inactivation were 8.36 kcal/mole and -58.2kcal/mole, respectively. The steady state kinetic study showed KG6P, Kemp, and CX KNADP to be 76.9 PM, 7.46${\mu}M$ and 7.14 ${\mu}M$, respectively, and KGGP, KNAD,and aKNm to be 53.7${\mu}M$, 115.2${\mu}M$ and 702.2${\mu}M$ for the $NAD^+$-linked reaction at pH 7.8, optimum pH. The pH dependent kinetic constants suggested that the two ionizing groups whose pKa is 7.2 .and pKb is 9.0-9.6 were involved in the enzyme-substrate interaction. Evidence by photooxidation and carboxymethylation of the enzyme suggested that the imidazole group of histidine with pKa group may participate in the catalytic site.

• Radiation Oncology Journal
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• v.30 no.3
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• pp.132-139
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• 2012

Purpose: The purpose of this prospective multi-institutional study was to evaluate the nutritional status of patients undergoing radiotherapy (RT) for treatment of head and neck, lung, or gastrointestinal cancer. Materials and Methods: A total of 1,000 patients were enrolled in this study at seven different hospitals in Seoul, Korea between October 2009 and May 2010. The nutritional status of patients after receiving 3 weeks of RT was evaluated using subjective global assessment (SGA). The nutritional status of each patient was rated as well nourished (A), moderately malnourished (B), or severely malnourished (C). Results: The mean age of patients in this study was $59.4{\pm}11.9$ years, and the male to female ratio was 7:3. According to the SGA results, 60.8%, 34.5%, and 4.7% of patients were classified as A, B, or C, respectively. The following criteria were significantly associated with malnutrition (SGA B or C; p < 0.001): loss of subcutaneous fat or muscle wasting (odds ratio [OR], 11.473); increased metabolic demand/stress (OR, 8.688); ankle, sacral edema, or ascites (OR, 3.234); and weight loss ${\geq}5%$ (OR, 2.299). Conclusion: SGA was applied successfully to assess the nutritional status of most patients. The prevalence of malnutrition in a radiation oncology department was 39.2%. The results of this study serve as a basis for implementation of nutrition intervention to patients being treated at radiation oncology departments.