• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.193-194
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• 2014

원전은 고온기능시험 이후 2차계통 내부를 상대습도 40%이하로 관리하여 계통 재질 부식을 최소화하고 있다. 일반적으로 발전소에서는 운전 정지 후 상대습도 40%이하로 낮추는데 15일정도 소요되지만, 발전소 계통 중 일부 곡관부위는 약 60일정도 소요된다. 본 연구는 일부 계통 재료가 상대습도 제한치(<40%) 이상의 환경에서 장기간(최대 60일) 노출시 재료 건전성에 미치는 영향 평가이다. 평가를 위해 시편의 실험 전, 후 무게변화를 이용한 부식률 측정과 표면분석을 위해 광학현미경을 이용하였다. 사용 시편의 재료는 SA516 Gr.70이며 표면상태를 인위적으로 산화피막을 생성 시킨 것(2개)과 산화피막이 없는 것(6개)으로 2종류로 제작하였다. 총 시험기간은 60일이고 시험기간 중 산화피막이 없는 시편은 7일, 21일, 60일에 시편을 2개씩 꺼내어 무게를 측정하여 부식률을 계산하였다. 실험결과, 산화피막이 없는 시편은 노출되는 시간에 따라 부식률이 각각 0.35(7일), 0.21(21일), 0.67(60일) mpy이었고 산화피막이 있는 시편은 0.06(60일) mpy였다. 산화표면 분석결과, 산화피막이 없는 시편은 노출되는 시간에 관계없이 물방울이 맺힌 부분에 pitting을 확인하였다. 하지만, 산화피막이 있는 시편은 pitting의 흔적은 없었다. 산화피막이 없는 시편의 경우 시간에 따라 부식률은 높아지지만 학계에서 통용되는 뛰어난 내부식성 재료의 부식률 기준인 < 1 mpy이하기 때문에 재료 건전성에 미치는 영향은 거의 없을 것으로 판단된다. 또한, 대부분 원전의 경우 고온기능시험 또는 운전기간 동안에 2차계통 구성 재료 표면에 산화막이 생성되었기 때문에 산화피막이 있는 시편의 결과로 판단하면 상대습도 40%이상에 60일 이상 노출되어도 부식은 거의 일어나지 않았을 것으로 사료된다. 실증실험결과를 가지고 종합적으로 평가하면 상대습도 40%이상 환경에서 곡관부위가 60일이상 노출되어도 재료 건전성에 미치는 영향은 거의 없을 것으로 판단된다.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.355-362
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• 2010

This study determines a range of CT parameter values in Brain CT which are minimizing patient absorption dose without compromising the image quality and optimal exposure condition. We measured dose and image noise using conventional CT parameters in Brain CT. In additon, we evaluated dose, SNR and PSNR of head phantom images while changing kVp and rotation time. In this study, effectiveness of dose that was achieved from dose reproducible experiments in conventional head CT condition is determined by changing kVp and rotation time. Dose and PSNR is related to low dose-high resolution condition. In conclusion, we suggest that using proposed conditions is effective for imaging to compare with conditions proposed by the manufacturer.

• Journal of Marine Life Science
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• v.7 no.2
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• pp.102-112
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• 2022

Crucian carp, Carassius carassius (Weight 39.7±3.1 g, Length 14.8±0.5 cm) were exposed to waterborne nickel at 0, 10, 20, 40, 80 and 160 mg Ni²⁺/l. The lethal concentration 50 (LC₅₀) of C. carassius exposed to waterborne nickel was 117.69 mg Ni²⁺/l. In hematological parameters, RBC counts was significantly increased at 48 hours, whereas a significant decrease was observed at 96 hours. The MCV and MCH were significantly increased in the concentration of 80 mg Ni²⁺/l at 96 hours. The plasma components such as calcium, magnesium, glucose, cholesterol, total protein, AST, ALT and ALP were significantly changed by waterbonre nickel exposure. The results of this study suggest that the nickel exposure to C. carassius affects the survival rates, hematological parameters and plasma components as toxicity

• Journal of fish pathology
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• v.26 no.2
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• pp.117-121
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• 2013

Three commercial exfoliating reagents, product A (main components: citric acid and vitamin C), B (herb) and C (nicotinamide), were used to study their exfoliation effect on abalone, Haliotis discus hannai from the substrate. The exfoliating reagents A, B, C and oxytetracycline (OTC, control) of 6-31.25 g/L and 12-37.5 g/L exfoliated 81.2-84.8% and 90.3-95% of abalone, respectively. Post-treatment recovery time for the abalone was similar for all the reagents except product C. Recovery period for the abalone immersed in OTC for 5-20 second was slightly shorter than the reagents A, B and C; however, no mortality was observed in any group except with the reagents B (concentration: 20 g/L, immersion time: 5 sec) and C (12 g/L, 10 and 20 sec) that showed negligible mortality of 3.3%. Higher concentration and longer treatment with the reagents resulted in longer recovery time of the detached abalone. Although abalone exposed to the reagents needs slightly longer time to recover than that to OTC, the exfoliation effect is much similar. These results indicate that the commercial exfoliating reagents can replace OTC to detach abalone, though they need to be cautiously handled.

• Pediatric Infection and Vaccine
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• v.22 no.2
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• pp.55-62
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• 2015

Purpose: Varicella Zoster Immune Globulin (VZIG) is available in Korea for post-exposure prophylaxis of the Varicella-zoster virus (VZV) in high-risk patients. In July 2013, the United States Centers for Disease Control and Prevention (US CDC) recommended extending the time for administration of VariZIG$^{(R)}$ from within 96 hours up to 10 days after VZV exposure. This study was performed to analyze the effectiveness of VZIG prophylaxis between the two groups of patients who received VZIG within 96 hours and more than 96 hours of exposure to varicella. Methods: A retrospective chart review was performed in pediatric patients who received VZIG at Samsung Medical Center, Seoul, Korea from January 2001 to December 2012. Results: A total of 91 patients were identified. Fifty-seven patients were male (62.6%) and the median age was 5.91 years. Thirty-nine patients (42.9%) were exposed to VZV in the hospital. Underlying diseases were solid tumors (41.8%), hematologic malignancies (40.7%), and others (17.5%). Forty-five patients (49.5%) were hematopoietic cell transplant recipients. Seventy-four patients (81.3%) received VZIG within 96 hours after VZV exposure. There was no significant difference in the development of chickenpox between the two groups (2.7% vs. 5.9%, P=0.4664). In 22 seronegative patients, we also observed no significant difference between the groups in terms of the development of chickenpox (6.6% vs. 0%, P=0.667). Conclusions: This study showed that the effectiveness of VZIG for the prevention of chickenpox was comparable between patients who received VZIG within 96 hours and those who received VZIG more than 96 hours after exposure to VZV.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.249-256
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• 1986

The carp (Cyprinus carpio) used in the experiment were hatched in the spring this year and reared to 5.96g($4.84{\sim}6.55g$) in mean weight in a nursery pond at Daeyon fish farm, Pusan, Korea. The sample fish were exposed to different conditions of total ammonia (TA-N) concentrations 10, 20 and 30ppm and pH 6.5, 7.0, 7.5 and 8.0 at water temperatures 20, 25 and $30^{\circ}C$ for 24, 48 and 72 hours. After the procedure, the gill, liver and kidney of the fish were examined histopathologically. In this experiment, with the rise of water temperature, increase of pH and ammonia concentration, and the extension of exposure time the three organs showed the tendency of apparent abnormal changes such as hypertrophy and necrosis in their tissues. At $20^{\circ}C$ of water temperature gill tissue did not show any abnormality regardless of the change of pH at 10 ppm of ammonia concentration for 24 hours of exposure, but beyond the conditions given above, there occurred hypertrophy and the epithelium of gill lamellae was detached. The detach of gill lamellae epithelium initiated from the proximal part of the gill lamellae then gradually spread toward the uppermost tip. The heavier vacuolation of the liver was observed with the rise of water temperature and pH, and such morbid state in the liver was considered to be the result of edema in the liver tissue. The kidney showed no damage to the renal tubule epithelium at pH 6.5, but it was damaged at pH 8.0 when exposed to 30 ppm ammonia at $20^{\circ}C$ for 24 hours.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.46-146
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• 2003

해양환경의 대표적 오염물질인 PAHs가 양식굴의 생리대사에 미치는 영향을 파악하고자, 서로 다른 PAHs 농도에 노출된 굴의 여수율, 호흡율, 배설율 및 동화율의 변화를 조사하였다. 부착생물을 깨끗하게 제거한 굴을 실험실로 옮겨 3일정도 순치시키고, 이후 각각의 0, 50, 100, 200ppb의 농도별로 약 10일간 미리 노출시켰다. 이후 각 개체별로 2L 들이 2$0^{\circ}C$항온수조에서 0.2$\mu\textrm{m}$ 여과해수를 사용하여 실험하였다. 여수율은 Chaetoceros simplex를 지표생물로 하여 수조내 시간당 감소율을 구하여 Kim(1995)의 식에 의해 구하였다. 호흡율은 유동파라핀으로 외부와의 공기접촉을 단절시키고, 수조내 단위시간당 DO meter로 산소변화를 측정하여 Widdows and Johnson(1988)의 식을 변형하여 계산하였다. 배설율은 단위시간동안 수조내 NH$_4$-N 농도 증가량으로 조사하였고, NH$_4$-N은 HACH Inc.에서 제공하는 측정법을 따랐다. 여수율은 500ppb에서 다소 영향을 받아 증가하였다. 호흡율과 배설율은 노출농도가 증가함에 따라 증가하였지만, 50ppb와 100ppb에서는 다소 차이가 없었다. 따라서 양식굴이 PAHs와 같은 오염물질에 노출되었을 경우, 초기에는 여수율의 변화는 없고 배설율과 호흡율이 상승하여 체내 에너지 요구량이 증가하는 것으로 생각된다.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.47-51
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• 1992

Volatile organic rompounds(VOCs) present in the VOCs-contaminated water are released to air while showering and their air concentrations depend on the shower parameters, resulting in the variation of the VOCs breath concentration. The present study evaluated the key shower parameters(water temperature and inhalation duration) that affect the inhalation exposure to air chloroform while showering, by determining chloroform breath concentration. The chloroform breath concentrations increased with water temperature and inhalation duration increase. The two inhalation exposure conditions which resulted in the greatest chloroform breath contentration difference were a 5 min-inhalation exposure with warm water and a 15 min-inhalation exposure with hot water. The chloroform breath concentration was almost three times higher after later exposure. The mathematical model analyzing the relationship between two key shower parameters and breath concentration normalized to water concentration fits quite Ivell with the experimental data at a probability of p : 0.0001.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.39-39
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• 2007

원자층 증착(Atomic Layer Deposition: ALD) 방법은 반응물질들을 펄스형태로 챔버에 공급하여 기판표면에 반응물질의 표면 포화반응에 의한 화학적 흡착과 탈착을 이용한 박막증착기술이다. ALD법은 기존의 화학적 기상증착(Chemical Vapor Deposition: CVD)과 달리 자기 제한적 반응(self-limiting reaction) 에 의하여 반응가스가 기판 표면에서만 반응하고 가스와 가스 간에는 반응하지 않는다. 따라서 박막의 조성 정밀제어가 쉽고, 파티클 발생이 없으며, 대면적의 박막 증착시 균일성이 우수하고, 박막 두께의 정밀 조절이 용이한 장점이 있다. 이러한 ALD 방식으로 3차원의 반도체 장치 구조물에 산화막 등을 형성하는 공정에서 중요한 요소 중의 하나는 전구체의 충분한 공급이다. 따라서 증기압이 높은 전구체를 선호하는 경향이 있다. 그러나 증기압이 낮은 전구체를 사용할 경우, 공급량이 부족하여 단차 도포성(step coverage)이 떨어지는 문제가 있다. 원자층 증착 공정에서 전구체를 충분히 공급하기 위해전구체 온도를 증가시키거나 전구체의 공급시간을 늘리는 방법을 사용한다. 그러나 전구체 온도를 상승시키는 경우, 전구체의 변질이나 수명을 단축시키는 문제점을 발생시킬 수 있으며. 전구체를 충분히 공급하기 위하여 전구체의 공급시간을 늘이는 방법을 사용하면, 원하는 박막을 형성하기 위하여 소요되는 공정시간과 전구체 사용량이 증가된다. 본 논문에서는 이러한 문제점을 해결하기 위해 반응기 안에서 전구체 노출 시간을 조절하는 새로운 ALD 공정을 소개한다. 특히 이러한 기술을 적용하면 나노튜브를 성장시키는데 매우 유리하다. 본 연구에서 전구체 노출 시간을 조절하기 위하여 사용된 ALD 장비는 Lucida-D200-PL (NCD Technology사)이며 (TEMA)Zr와 H2O를 사용하여 ZrO2 나노튜브를 폴리카보네이트 위에 성장시켰다. 전구체의 노출 시간은 반응기의 Stop 밸브를 이용하여 조절하였으며, SEM, TEM 등을 이용하여 나노튜브의 균일성과 단차피복성 등의 특성을 관찰하였다. 그 결과 전구체 노출시간을 조절함으로써 높은 종횡비를 갖는 나노튜브를 성장 시킬 수 있음을 확인하였다. 또한 낮은 증기압을 가지는 전구체를 이용하여도 우수한 특성의 나노튜브를 균일하게 성장시킬 수 있었다.

• Korean Journal of Environmental Agriculture
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• v.7 no.2
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• pp.124-129
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• 1988

Prolonged aquatic toxicity tests (7-days) of six pesticides to the freshwater fish Oryzias latipes were performed to confirm the adequacy of the exposure times, 48-hr or 96-hr, which has been required by the protocols for the aquatic acute toxicity test. The toxicity curves were plotted for each chemical, and the significance of the difference between lethal threshold concentrations and 48-hr or 96-hr LC50's was analysed statistically. The lethal threshold concentrations of butachlor, fenobucarb, and chlorothalonil were clearly defined on the 5th day, 2nd day, and 2nd day at 0.53mg/1, 10.3mg/l, and 0.085mg/1, respectively. But the toxicity curves of alachlor, diazinon, and iprobenfos continued with no threshold for 7 days. Four out of six test pesticides failed to show the threshold concentration during the 96-hr exposure time. Therefore, the results of the acute toxicity test using 48-hr or 96-hr exposure time would not describe the ideal toxicity of pesticides. It is recommended that the prolonged exposure should be continued long enough to define the threshold adequately.