• Microbiology and Biotechnology Letters
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• v.20 no.1
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• pp.79-84
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• 1992

The Photosynthetic bacterium, Rhodopseudomonas sphaeroides strain B6 was irnmobilized on agar gel. The optimum concentration of agar for hydrogen production was 2% (w/v). Maximum rates of hydrogen production by immobilized (300 ml of gel; 2.85 rng dry cells/ml) and free cells (1l culture; 0.87 mg dry cells/ml) were 47.5 and 48.0 ml/hr/culture, respectively. However, when both cultures were fed by 10 mmoles of lactate as limited electron donor at the later period of incubation, the activity of hydrogen production by free cells was significantly decreased but, immobilized cells continued hydrogen production with almost the same initial rate. Wc examined hydrogen production by immobilized cells of strain B6 under periodic illumination for 12 hr-intervals. When the culture was periodically fed by basal medium containing 9.3 rnmoles of DL-lactate and 1.86 mmoles of L-glutamate as consumed electron donor and nitrogen source, respectively, for every one liter of hydrogen produced, hydrogen was evolved continuously with the average rate of 510 ml/day/300 ml gel (2.9 rng dry cellslml) during the incubation time for 228 hr.

• Korean Journal of Food Science and Technology
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• v.43 no.4
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• pp.458-463
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• 2011

Recent studies have revealed that collagen peptide (CP) plays a protective role in skin by improving the activity of antioxidants and acts as an inducer of skin regeneration by positive feedback. In this study, we focused on the beneficial effect of reinforcing the CP skin barrier. To evaluate the skin barrier, hairless mice were exposed to UVB irradiation and acetone-treatment, with or without oral administration of CP. The effects on skin appearance, trans-epidermal water loss, epidermal thickness, and cytokine content were measured using bioengineering and histochemical methods. In the CP treated group, the skin had better appearance and less damage than that of the control. Furthermore, in HaCaT cells, the amount of serinepalmytoyl transferase (SPT) mRNA increased by about 1.6-fold after treatment (CP, 100 mg/L), reflecting that CP can induce SPT expression and reinforce the recovery of skin barrier function. These results suggest that CP is not only an anti-wrinkling agent but also a potent candidate as an epidermal moisturizer.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.453-453
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• 2012

최근 디스플레이 시장에서는 저전력 자발광 소자인 OLED가 많은 관심 속에 연구 진행 되고 있다. 높은 효율과 투명, 플렉서블 디스플레이가 실현 가능한 OLED 소자는 초기 수명감소, 저전압구동 및 신뢰성에 대한 문제점을 개발 중에 있기에 많은 가능성을 현실화 하지 못하고 있다. 따라서 본 연구에서는 OLED소자의 역방향 반송자 회복 수명을 측정함으로써 스트레스에 의한 소자 열화를 전기적으로 분석하는 방법을 제시하고자 한다. 우선 5cm5cm의 면적에 네 개의 픽셀이 들어가는 후면 발광 Blue OLED를 제작하고 $-40^{\circ}C$부터 $100^{\circ}C$까지 $10^{\circ}C$간격으로 온도 스트레스를 주어 수명을 측정하였다. 전원공급기를 사용하여 직류 전압을 2V 인가하고 함수 발생기를 사용하여 +3V, -0.5V의 구형파를 500 kHz 주파수로 인가하였다. 이러한 조건으로 측정된 소자는 오실로스코프를 이용하여 전압 회복시간을 측정하고 온도 스트레스에 따른 수명을 산출하였다. $-40^{\circ}C$일 때 는 약 1.92E-7s이고 $100^{\circ}C$일 때 는 약 1.49E-7s로 약 0.43E-7s정도 감소하였다. 양의 전압이 인가되었을 때의 소자 내부의 전압은 온도가 증가함에 따라 꾸준히 감소하였고, 이에 따라 또한 꾸준히 감소하였다. 그러나 음의 전압이 인가되는 부분에서는 무설 전류에 의하여 음의 방향으로 흐르게 되는 전압의 절대값이 꾸준히 증가하였고 대체적으로 온도가 증가함에 따라 그래프가 아래로 이동하는 현상이 관찰되었다. 이러한 경향은 이상적인 다이오드의 반송자 축적 식을 통하여 온도가 증가함에 따라 가 증가하는 것과 관련이 있음을 확인하였다. 따라서 다수 층의 레이어로 이루어진 OLED소자의 열적 스트레스에 대한 수명 변화의 물리적 조건이 이상적인 다이오드 특성에 부합한다는 것을 확인하였다.

• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.123-131
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• 1997

The alternation of light transmissivity of covering films used in most greenhouses over years become of concern. Recently, durable films over 0.1mm in thickness which having 3~5 years life time were popularly used in many greenhouses. However, the films have been replaced yearly with new ones because of lowering light transmittance. The replacement caused negative environmental impact as well as cost increasement. This study was conducted to find fundamental data for developing of a cleaning machine for covering films of greenhouses.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.40 no.4
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• pp.321-330
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• 2014

Ultraviolet B (UVB) is a primary environmental factor that induces adverse effects on skin such as photoaging, skin burn and cancer. UVB also increases the expression of $11{\beta}$-hydroxysteroid dehydrogenase type 1 ($11{\beta}-HSD1$), which converts inactive cortisone to active cortisol in response to a variety of stressors in target tissues. Thus, we have screened new herbal extracts that suppress $11{\beta}-HSD1$ expression induced by UVB in human dermal fibroblasts. We also investigated whether Trapa japonica (TJ) extract and its fractions inhibit UVB-induced photoaging in Hs68 cells and 3D skin model. Results showed that TJ extract inhibited the increase of $11{\beta}-HSD1$ expression in UVB-exposed Hs68 cells significantly. TJ extract and its fractions not only inhibited $11{\beta}-HSD1$ expression, but also suppressed the increase of matrix metalloproteinases (MMP-1, 3, 9) and proinflammatory cytokines (IL-6, 8) in UVB-irritated Hs68 cells. TJ extract also inhibited MMP-1 expression in UVB-irritated 3D skin model. In addition, TJ extract recovered UVB-induced decreases of epidermal thickness and PCNA-positive cells in 3D skin model. Taken together, these results suggest that TJ extract and its fractions inhibit UVB-induced skin photoaging by interfering with $11{\beta}-HSD1$ and MMPs.

• (The)Study of the Eastern Classic
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• no.57
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• pp.103-136
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• 2014

This is the paper on the descriptive perspective and writing method in Yeheon(旅軒)'s Piranrok(避亂錄). Piranrok was Yeheon's diary which was written during Japanese invasions of Korea. Many intellectual recorded their diaries during the war. Yeheon's Piranrok was a typical example among war journals. I tried to take view of the descriptive perspective and writing method in Yeheon's Piranrok. First, sourceful introspection was distinct characteristic in the descriptive perspective. Yeheon penetrated into a chaotic state of affairs during Japanese invasions of Korea. And Yeheon had reflective consciousness about self-existence. He contemplated his existence through diary writing. I had a task to study the writing methods in Yeheon's diary. One of the distinct characteristic in writing methods was to increase specific gravity of discussion. Yeheon advocated strongly his opinion and position about cause of war, war responsibility, morality, fortification and righteous army. Yeheon made the best use of communication method and catechetic method. He answered his own questions about the enter and retirement of public office. He expressed his worry and conflict through various techniques of expression. I have a task to study the diary in Chosun dynasty. I believe that analyzing characteristics of Yeheon's diary can contribute to understanding the literature history of diaries in Chosun dynasty.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.3
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• pp.624-634
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• 1998

The photoelastic model material with shape memory effect and the molding processes for the material are developed in this research. The matrix and fiber of the photoelastic model material developed in this research are epoxy resin (Araldite to hardner 10 to 3 (weight ratio)) and wire of $Ti_50-Ni_50$ shape memory alloy, respectively. It is called Ti50-Ni50 Shape Memory Alloy Fiber Epoxy Composite $(Ti_50-Ni_50SMA-FEC).$ Ti50-Ni50 SMA-FEC is satisfied with the requirements of the photoelastic model material and can be used as a photoelastic model material. The maximum recovering strain of $Ti_50-Ni_50$SMA-FEC is occurred at $80^{\circ}C$ in any prestrain of $Ti_50-Ni_50$ shape memory alloy fiber and in any fiber volume ratio. Recovering strain(force) is increased with the increment of the prestrain and the fiber volume ratio. The best prestrain of $Ti_50-Ni_50$SMA-FEC is 5% for the recovering force among 1%, 3%, 5%.

• Journal of radiological science and technology
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• v.42 no.5
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• pp.379-385
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• 2019

Radiation is used for various purposes such as cancer therapy, research of industrial and drugs. However, in case of radiation accidents such as terrorism, collapsing nuclear plant by natural disasters like Fukushima in 2011, very high radiation does expose to human and could lead to death. For this reason, many people are concerning about radiation exposures. Therefore, assessment and research of retrospective radiation dose to human by various path is an necessary task to be continuously developed. Radiation exposure for workers in radiation fields can be generally measured using a personal exposure dosimeter such as TLD, OSLD. However, general people can't be measured radiation doses when they are exposed to radiation. And even if radiation fields workers, when they do not in possession personal dosimeter, they also can't be measured exposure dose immediately. In this study, we conduct retrospective research on reconstruction of dose after exposure by using smart chip card of personal items through Optically Stimulated Luminescence (OSL). The OSL signal of smart chip card shows linear response from 0.06 Gy to 15 Gy and results of fading rate 45 %, 48% for 24 and 48 hours due to the natural emission of radiation in sample, respectively. The minimum detectable limit (MDD) was 0.38 mGy. This values are expected to use as correction values for reconstruction of exposure dose.

• Journal of Dental Rehabilitation and Applied Science
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• v.37 no.4
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• pp.217-224
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• 2021

Purpose: The purpose of this study was to evaluate the porosity of resin modified glass ionomer (RMGI) by different mixing methods. Materials and Methods: Five specimens were prepared for each groups according to capsules and mixing methods. Two RMGI capsule and two mixing machines were used for this study. One resin-modified glass ionomer cement is Fuji II LC (F2LC) and the other is Photac Fil Quick Aplicap (PFQ). For Mixing of RMGI capsule, Rotomix using rotating motion and CM-II using shaking motion were used. After measuring height, radius and mass of specimens, Density was calculated. And porosity was measured using micro-computed tomography (micro-CT). All data were statistically analyzed using T-test, two-way ANOVA to compare between groups at 95% significance level to evaluate the affect of capsule and mixing method on the porosity. Results: The porosity was observed in all specimens generally. And there is significant differece between porosities according to RMGI capsule and Mixing method. The porosity of PFQ was lower than that of F2LC and the porosity of Rotomix was lower than that of CM-II. Conclusion: There was a difference of porosity according to kind of capsules and mixing methods. When using same capsule, less porosity was observed on PFQ than F2LC. When using same mixing mehod, less porosity was observed on Rotomix than CM-II. Using mixing machine of same coporation as that of RMGI capsule did not lead to lower porosity. Therefore, Selecting optimal mixing machine is important.

• Journal of Bio-Environment Control
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• v.10 no.3
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• pp.159-164
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• 2001

This study were conducted to investigate the influence of chilling on photosynthetic rate, root activity, contents of total sugars and fatty acids of cucumber seedlings grown in a greenhouse. Even though photosynthetic activity of seedlings exposed to $0^{\circ}C$ for 5 hours was little or insignificantly influenced, it was reduced by 52.8% and 67.7% in seedlings exposed to the same temperature for an extended 10 and 24 hours, respectively. Photosynthetic rate decreased significantly when seedlings were illuminated, as compared to continuously held under darkness, during 15 hours of chilling treatment at 3$^{\circ}C$. Recovery of photosynthetic ability was also retarded by illumination during a recovery period after chilling treatment. Root activity, as measured by the oxidation power of $\alpha$-naphtylamine, was significantly reduced by chilling treatment at 0 to 6$^{\circ}C$, but amount of bleeding xylem sap collected at 40 days after chilling treatment was not significantly different among treatments. Total sugar content increased by 12 and 23% as compared to the control in seedlings chilled for 24 hours, respectively, at 3$^{\circ}C$. Contents of unsaturated linolenic and oleic acids increased, while content of saturated palmitic acid decreased with chilling treatment.