• 한국재료학회지
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• 제4권3호
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• pp.357-363
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• 1994

국산 핵연료에 사용되는 KOFA Zircaloy-4피복관의 조사성장 거동을 평가하고 제조 공정이 서로 다른 Siemens사 피복관의 조사성장거동과 비교하기 위하여 고리 2호기에 장전된 핵연료 피복관의 조사성장이 측정되었다. KOFA Zircaloy-4피복관은 최종 열처리시의 부분 재결정화로 인하여 fully annealed Zircaloy피복관고 Siemens사 피복관의 측정된 조사성장율이 차이는 제조공정의 차이에 기인한 피복관 집합도 계수의 차이로서 설명할 수 있었다. 고리 2호기 국산핵연료에서 측정된 자료를 이용하여 KOFA Zircaloy-4 피복관의 2단계 조사성장 모델이 유도되었는데 향후 측정자료가 많이 축적되면 유도된 모델의 정확성이 보다 명확하게 검증될 수 있을 것이다.

• Journal of Photoscience
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• 제9권2호
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• pp.158-161
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• 2002

UV-B radiation gives harmful effects on plants, such as production of several types of DNA lesions, and growth inhibition. On the other hand, plants have some protective mechanisms, including filtering effect due to accumulation of phenolic compounds in epidermal cells and reactivation of DNA lesions, which are enhanced by UV-B irradiation. We have investigated the mechanism of UV-B effects on plants using cucumber seedlings as plant materials. Cucumber plants were cultivated in an artificially lit growth chamber. Supplemental UV-B irradiation, of which intensity was almost equal to the level of natural sunlight, retarded the growth of first leaves. The growth retardation must result trom the inhibition of cell division and/or cell growth. Microscopical observation of leaf epidermis suggested that the growth retardation might be mainly caused by cell growth inhibition. The retardation was, however, restored within 2 or 3 days after the termination of UV-B irradiation. It is known that UV-B irradiation lowers the activity of photo system II (PS II). In the present experimental conditions, however, UV-B irradiation has little effect on PS II activity as estimated by chlorophyll fluorescence. The stomatal conductance, a major factor determining photosynthetic rate, of first leaves increased during the growth. The increase of stomatal conductance was suppressed by UV-B irradiation and restored by termination of the irradiation. It has not been clear, however, what mechanisms are involved in the suppression of increase of stomatal conductance.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제33권6호
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• pp.617-624
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• 2007

Insulin-like growth factor(IGF) is the most abundant growth factor in bone matrix. Recent studies have shown that it can sensitize apoptotic cell death of osteoblasts. Thus, this study investigated whether IGF-II aggravates irradiation-induced cell death of osteoblasts. Cultured MC3T3 osteoblasts were irradiated and IGF-II was added at the concentration of 50 ng/ml immediately after the irradiation. Cell viability was measured by MTT assay. Changes in cell death and cell cycle were analyzed by flow cytometry. The expression of proapoptotic gene bax and antiapoptotic gene bcl-2 was quantified by real time RT-PCR and Western blot. A dose of 30 Gy caused G2/M arrest and increased cell death through both necrosis and apoptosis, while irradiation from 4 to 10 Gy little affected cell cycle and death. IGF-II treatment reduced cell viability without stimulating cell proliferation and changing cell cycle. Combined treatment of IGF-II with irradiation decreased cell viability and proliferation and increased cell death along with G2/M arrest. These effects were not different from those of irradiation only. At transcriptional and protein levels, IGF-II treatment did not affect bax and bcl-2 expression, whereas irradiation increased the expression ofbax without changes in bcl-2. IGF-II in combination with irradiation showed similar findings. These results suggest that IGF-II could modulate apoptotic cell death through mechanisms other than an imbalance between bax and bcl-2 gene expression, although its effect was overridden by irradiation.

• 한국환경과학회지
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• 제7권4호
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• pp.487-492
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• 1998

The experiment was conducted to determine the effects of enhanced UV-B on growth and differential responses among cultivars in soybean. The soybean cultivars subjected to enhanced UV-B irradiation at daily dose of 11.32 kJ $m^{-2}(UV-B_{BE})$ revealed that the growth was significantly depressed. Plant height, leaf number, leaf area and dry weight were inhibited by UV-B irradiation showing differential responses among cultivars used. Danyeubkong seems to be less sensitive to the enhanced W-B irradiation, while Keunolkong more sensitive. Reduction of chlorophyll content was also found significantly greater to Keunolkong. Specific leaf weight an index of leaf thickness, and flavonoid content known as UV-absorbing compounds were significantly Increased in Danyeubkong by UV-B, but those In the other cultivars were not significantly affected. The results indicated that there are cultivar diferences in tile growth and phisiological responses to the enhanced UV-B irradiation and specific leaf weight and UV-absorbing compounds in the leaves were highly related to the sensitivity of soybean by UV-B irradiation.

• Journal of Microbiology and Biotechnology
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• 제24권2호
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• pp.209-216
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• 2014

The efficiency of gamma irradiation (0, 1, 5, 10, 15, 20, and 30 kGy) as a sterilization method of corn samples (30 g) artificially contaminated with Fusarium moniliforme stored at normal condition ($25^{\circ}C$ with approximate relative humidity (RH) of 55%) and optimal condition ($25^{\circ}C$ with a controlled RH of 97%) was studied. The results showed that the fungal growth and the amount of fumonisin were decreased as the dose of gamma irradiation increased. Gamma irradiation at 1-5 kGy treatment significantly inhibited the growth of F. moniliforme by 1-2 log reduction on corn samples (P < 0.05). Sublethal effect of gamma irradiation was observed at 10-20 kGy doses after storage, and a complete inactivation required 30 kGy. Fungal growth and fumonisin production increased with higher humidity and longer storage time in all corn samples. This study also demonstrated that there was no strict correlation between fungal growth and fumonisin production. Storage at normal condition significantly resulted in lower growth and fumonisin production of F. moniliforme as compared with those stored at optimal condition (P < 0.05). Gamma irradiation with the dose of ${\geq}5$ kGy followed by storage at normal condition successfully prolonged the shelf life of irradiated corns, intended for human and animal consumptions, up to 7 weeks.

• Imaging Science in Dentistry
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• 제30권1호
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• pp.71-79
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• 2000

Purpose : This study was aimed to evaluate the cell cycle arrest and apoptosis induction after irradiation and epidermal growth factor (EGF) treatment in three human epithelial tumor cell lines (A431, Siha, KB). Materials and Methods: Single irradiation of 2, 5 and 10 Gy was done on three cell lines with 5.38 Gy/min dose rate using Cs-137 irradiator at room temperature. Also, EGF of 10 ng/ml was added immediately after 10 Gy irradiation. Cell growth was evaluated by counting the living cell number using a hemocytometer at 1 day, 2 days, 3 days, 4 days and 5 days after irradiation. Cell cycle arrest and apoptosis induction were assayed with the flow cytometry at 8 hours, 12 hours, 1 day, 2 days, 3 days, 4 days and 5 days after irradiation. Results : Growth of irradiated three cell lines were inhibited in proportion to radiation dose. EGF treatment after irradiation showed various results according to cell lines. On all cell lines, G2 arrest was detected after 8 hours and maximized after 12 hours or 1 day. Amount of G2 arrest was positively dose dependent. However, EGF showed no significant change on G2 arrest. G2 arrest was recovered with time at 2 Gy and 5 Gy irradiation. However, at 10 Gy irradiation, G2 arrest was continued. Apoptosis was detected at 10 Gy irradiation. On EGF treated group after irradiation, A431 and Siha cell lines showed slightly increased apoptosis but there was no statistically significant difference. KB cell line showed no marked change of apoptosis induction. Conclusion : Irradiation effects on cell cycle arrest and apoptosis induction in three human epithelial tumor cell lines, however epidermal growth factor doesn't effect on.

• 환경생물
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• 제21권4호
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• pp.400-404
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• 2003

This study was to evaluate the effects of gamma irradiation on the germination, nutrient concentrations and growth of spinach and radish. Both the spinach and radish seeds exhibited relatively higher germination rates in response to the low doses of gamma irradiation compared to the non -irradiated control. Leaf DW of the radish did not respond to gamma irradiation but that of the spinach increased significantly in response to a gamma radiation of 4 Gy (P< 0.05). Leaf growth parameters of the spinach including the leaf area and SLA (leaf area/leaf dry weight) also demonstrated increased responses to gamma irradiation. R/S (root dry weight/shoot dry weight), root DW and root length of the spinach exhibited a positive response to gamma irradiation while those of the radish did not. In contrast, SRL (root length/root dry weight) significantly decreased with gamma irradiation at 8 Gy for the spinach, but not for the radish. The tissue nitrogen concentrations of the spinach showed an increased response to gamma irradiation while that of the radish did not. Furthermore, higher concentrations of phosphorus, potassium, calcium and magnesium were found in the irradiated spinach, but not in the irradiated radish. It seems that the non-specific physiological and/or biochemical activities of spinach might be accelerated by gamma irradiation, possibly accounting for the stimulation of nutrient uptake from the root media and early biomass accumulation in the current study.

• 상하수도학회지
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• 제31권5호
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• pp.441-445
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• 2017

This study aimed to investigate growth rate and nutrient consumption of Chlorella vulgaris according to different light irradiation interval. Applied light irradiation intervals were 12 hr, 4 hr, 1 hr, and 1 min. The light source was flexible LED(Blue:Red=1:1), light intensity was 200 PPFD and Light/Dark cycle was 1:1. As a result, growth rate and nutrient removal efficiencies showed no significant differences depending on the light irradiation interval. Considering the reproduction characteristics of applied microalgae cultures of this study, this is thought to be one of the possible reasons of above results. Because Chlorella vulgaris performs an asexual reproduction and it is known that there is no significant relationship between light irradiation interval and growth rate, including nutrient consumption in case of asexual reproduction.

• Ecology and Resilient Infrastructure
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• 제9권3호
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• pp.183-193
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• 2022

초음파 (ultrasonic) 조사시간 (irradiation time)에 따른 Microcystis aeruginosa (M. aeruginosa)의 성장억제 (growth inhibition) 효과를 대용량 (10 L) 조류 시료를 활용해 다양한 초음파 조사시간 동안 (0.5, 1, 1.5, 2, 2.5, 3 hr) 실험실 규모 (lab-scale) 실험을 진행하였다. Chl-a와 M. aeruginosa 개체수 (cell number) 분석 결과, 초음파 조사 종료 이후 모든 실험군에서 Chl-a와 개체수가 감소되어 조류 성장억제가 관찰되었으며, 초음파 조사시간이 2시간 미만인 실험군 (T_B, T_C, T_D)은 저감 이후 조류의 급격한 재성장 (regrowth)이 관측되었으나, 조사시간이 2시간 이상인 실험군 (T_E, T_F, T_G)은 2시간 미만 조사한 실험군 대비 조류성장억제가 1 - 2일 더 지속되는 것을 확인하였다. 또한, 조류의 개체수가 초기 개체수까지 회복 시간 (recovery time)을 검토한 결과 조사시간 2시간을 기준으로 실험군 T_B (0.5 hr)는 7일, T_C (1 hr)와 T_D (1.5 hr)는 약 20일, T_E, T_F, T_G (≥ 2 hr)는 약 30일이 소요되어 초음파 조사 종료 후 초기 개체수까지의 회복 시간의 차이를 확인하였다. 비성장속도 (𝜇)와 일차분해속도(𝜅)를 도출한 결과, 실험군은 성장억제 기간 동안 초음파 조사시간과 비례하여 높은 일차분해율이 도출되었으며, 조사시간이 2시간 이상인 실험군의 재성장 시 비성장속도 (𝜇)는 2시간 미만인 실험군 대비 비성장속도 (𝜇)가 상대적으로 낮은 것으로 확인되었다. 따라서 정체수역 내 장기적인 (30일) 조류 성장억제를 위해서는 최소한 2시간 이상의 초음파 조사가 필요한 것으로 판단되나, 조류 성장억제를 위한 적정 초음파 조사시간은 정체수역의 규모, 수심, 흐름속도, 조류 농도 등의 다양한 현장조건에 따라 결정돼야 하며, 실제 적용 가능성을 높이기 위한 추가 연구가 필요한 것으로 판단된다. 초음파의 영향으로 인한 M. aeruginosa의 세포 표면 및 내부형질 변화를 관찰한 결과, 조류 세포 표면 및 세포막의 손상이 명확히 관측되었으며, 대조군 대비 실험군의 M. aeruginosa의 기낭 파괴 및 교란이 확인되었다.

• Archives of Plastic Surgery
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• 제32권2호
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• pp.149-154
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• 2005

Low-power laser(LPL) delivers a small amount of energy without elevation of tissue temperature. LPL has been reported to have biostimulation effects including anti-inflammatory, analgesic, regenerative, immunocorrective, and vasodilative effects. However, the effect of LPL on hair growth has rarely been studied. We investigated the effect of LPL on hair growth in the mouse. After depilation of back skin of mice, we classified the mice into 4 groups: control, laser irradiated group, $MoandMore^{(R)}$ applied group, and Spella $707^{(R)}$ applied group. Laser irradiation or application of these drugs were performed on the back skin of the mice for 30 days. The results are summarized as follows. Hair growth of control was first observed at 13 days after depilation, and complete hair regrowth was observed at 25 days. Hair growth of both laser irradiation group and $MoandMore^{(R)}$ applied group was first observed at 9 days after depilation, and complete hair regrowth was observed at 20 days. Hair growth of Spella $707^{(R)}$ applied group was firstly observed at the 9 days after depilation, and complete hair regrowth was observed at the 15 days. Hair growth started at the irradiation site in the laser irradiation group, but it started at the random sites in other groups. In conclusion LPL irradiation have a stimulating effect on the hair growth in the mouse.