• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.11a
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• pp.72-72
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• 1998

원자력발전소 1차계통내 밸브의 경면처리(hardfa따1잉에 사용되는 재료는 $90~343^{\circ}C$의 고온과 높은 접촉응력 그리고 급격한 압력변화가 일어나는 환경에서 사용되기 때문에 내마모성과 내식성 그리고 cavitation erosion 저항성이 우수한 Co계 Stellite 합금이 현재 사용되어진다. 그러나 Co가 원력발전소 1차계통의 방사선장을 형성하는 주요 원소로 알려지면서 S Stellite 합금을 대체할 수 있는 Fe계 경면처리용 합금을 개발하려는 연구가 진행되고 있다. 현재 Fe계 경면처리용 합금의 개발은 적절환 팝금원소를 첨가하여 적충결함에너지를 낮춤 으로써 전위의 교차슬립을 억제하여 표면을 경화시키고, 소성변형을 억제하여 마모저항성을 향상시키려는 방법으로 연구가 진행되고 있다. 본 연구에서는 Fe-Cr-Ni-Si-C 합금에 Fe계 합금의 적충결함에너지를 감소시키는 것으로 알려진 vanadium을 0, 1, 2wt%첨가하여 첨가량의 변화가 cavitation erosion 저항성에 미치 는 영향을 조사하였다. Cavitation erosion 실험은 초음파를 이용하여 미세한 기포를 발생시키는 vibratory type으로 A ASTM G-32 규격에 따라 제작된 실험장치를 이용하여 $25{\pm}2^{\circ}C$의 온도의 증류수 속에 잠긴 상태에서 실시하였다. 시면은 지름 16mm, 두게 7mm의 버턴형태로 vanadium 첨가량을 변화시킨 조성을 아크 용융 방법을 이용하여 제작하였으며 hom끝단부에 부착하여 cavitation e erosion 저항성 살험을 하였다. 시편의 cavitation erosion 실험시간에 따른 무게감소량을 측 정하였으며 cavitation erosion 시킨 시편의 표면을 SEM으로 관찰하였다.겨지는 열전달 매체액 과 신규 부식억제제가 적용된 시스템 등 객관적으로 확인된 부식억제제 시스랩에 대 하여 다양한 평가 방법을 동원 비교분석하고자 하였다. 실험은 KSM 2142에 의한 무게감량법, 분극곡선 측정에 의한 $E_P$(공식개시전위), $E_R$(재부동태화전위) 측정, 시간에 따른 자연전위 변화 측정 빛 이때의 부식속도(선형분극법), 인위적인 피막 파괴 전,후 의 전위 변화 및 부식속도 측정법에 의한 국부부식 발달 저지능 등을 평가하여 각 실험결과를 비교분석하여 보았다. 수록 민감하여 304 의 IGSCC 와 매우 유사한 거동을 보인다. 본 강연에서는 304 와 600 의 고온 물에서 일어나는 IGSCC 민감도에 미치는 환경, 예민화처리, 합금원소의 영향을 고찰하고 이에 대한 최근의 연구 동향과 방식 방법을 다룬다.다.의 목적과 지식)보다 미학적 경험에 주는 영향이 큰 것으로 나타났으며, 모든 사람들에게 비슷한 미학적 경험을 발생시키는 것 이 밝혀졌다. 다시 말하면 모든 사람들은 그들의 문화적인 국적과 사회적 인 직업의 차이, 목적의 차이, 또한 환경의 의미의 차이에 상관없이 아름다 운 경관(High-beauty landscape)을 주거지나 나들이 장소로서 선호했으며, 아름답다고 평가했다. 반면에, 사람들이 갖고 있는 문화의 차이, 직업의 차 이, 목적의 차이, 그리고 환경의 의미의 차이에 따라 경관의 미학적 평가가 달라진 것으로 나타났다.corner$적 의도에 의한 경관구성의 일면을 확인할수 있지만 엄밀히 생각하여 보면 이러한 예의 경우도 최락의 총체적인 외형은 마찬가지로 $\ulcorner$순응$\lrcorner$의 범위를 벗어나지 않는다. 그렇기 때문에도 $\ulcorner$

• Journal of radiological science and technology
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• v.28 no.3
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• pp.241-248
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• 2005

X-ray examinations represent the largest man-made source of radiation exposure for the population. The need for standardization of radiation exposures has been suggested and the guidance levels for various radiographic and radioisotope examinations has been proposed by the International Atomic Energy Aency(IAEA) as a safety standard. In many countries, the situation of medical radiographic exposures in each country should be researched before the appropriate guidance level is established. In this study, measurements of entrance surface dose, dose-area product(DAP), computed tomograghic dose index(CTDI) and mean glandular dose(MGD) were carried out in patients who underwent routine x-ray examinations, fluoroscopy, computed tomograghy and mamography in Korea. These measured quantities were compared with the results from the calculation method in previous study. And we suggested diagnostic reference levels in medical imaging in Korea.

• Journal of Veterinary Clinics
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• v.30 no.2
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• pp.87-94
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• 2013

This retrospective study reviewed the clinical and diagnostic features, therapeutic outcome and compilations of interventional ductal occlusion in 37 dogs with patent ductus arteriosus (PDA). Malteses and female dogs were over-presented. Bounding pulse and left basal continuous murmur were most common findings in physical examination, while the differential cyanosis was rarely observed. Left ventricular (LV) enlargement patterns and sinus tachycardia were common in the ECG. Typical radiographic findings included LV elongation and triple bumps indicating left atrial (LA), aortic and pulmonary dilation. Echocardiographic features were typical shunt flow at the ductus arteriosus and marked LV dilation with mild to moderate mitral regurgitation (MR). The 32 of 37 dogs were interventionally treated with either thromboemolic coils (TCE) or Amplatz canine ductal occluder (ACDO). Transient hemoglobinuria caused by incomplete closure was occurred in 2 dogs treated with TCE, although the hemoglobinuria was disappeared within a week of intervention. The dislodgement of occlusion device was occurred in 2 dogs with TCE and 1 dog with ACDO. However there were no significant complications associated with this dislodgement, since those were dislodged at the lower pulmonary vasculature. We also found that no serious complications and no further medical intervention in 29 dogs having long-term follow-ups.

• Korean Journal of Food Science and Technology
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• v.10 no.3
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• pp.313-319
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• 1978

In order to investigate the effect of dietary long chain fatty acids on fatty acid biosynthesis of liver in birds, single comb White Leghron male chicks were fed a fat-free diet an diets containing margaric, stearic and linoleic acids and liver lipid components and liver and plasma fatty acid distributions were compared. Total lipids of tissues were extracted with a chloroform-methanol mixture. The lipid components were determined by thin layer chromatography and fatty acid distribution of lipid fractions were determined by gas liquid chromatography. Fatty acid feeding did not affect liver lipid components. When margaric acid(17 : 0), was fed, 17:0 and heptadecenoic acid(17:1) appeared in every lipid fractions of liver and plasma, and distribution values of these acids were not significantly different between the lipid fractions of liver. In blood plasma of the 17 : 0 fed chicks, however, significantly higher distribution values of 17 : 0 and 17.1 were observed in the triglyceride fraction and in the cholesterol ester fraction, respectively. Dietary stearic acid (18 : 0) did not show any effect on the distribution of 18 : 0 in every lipid fractions of liver but showed a significantly higher distribution value of 18 : 0 in the free fatty acid fraction of plasma. When linoleic acid (18 : 2) was fed, every lipid fractions of liver and plasma contained 18 : 2, especially a significantly higher distribution value was observed in the phospholipid fraction of liver. Dietary margaric and linoleic acids tended to decrease the distribution value of endogenously synthesized palmitoleic (16 : 1) and oleic (18 : 1) acids in liver.

• Journal of the Korean Society of Radiology
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• v.12 no.6
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• pp.719-725
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• 2018

After 9/11 attacks in the U.S, Terrorism has increased the number of unspecified casualties through multi-use facility terror attacks compared to the past. The subsequent London bombings and the self-destruction of Pakistan increased people's fear and social anxiety. As international events have been held in Korea recently, awareness and concern over radioactive terrorism and security management of radioactive materials are increasing. In this paper, we compared the results of different meteorological conditions using HotSpot Code. After creating a possible terror scenario in Korea, sources likely to be use in RDD and Dirty bomb were investigated. The meteorological condition was selected by comparing the Pasquill-Gifford stability class with the most stable condition F and the most unstable condition A. The result value of the A and F condition through simulation were shown not to cause citizens to die from acute effects due to radiological effects. The range of radioactivity is different according to the wind speed and the meteorological stability, and the degree of radioactivity dilution is different according to meteorological conditions. Analysis results are expected to be used for initial response in the event of a radioactive terrorist attack.

• Journal of Food Hygiene and Safety
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• v.33 no.6
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• pp.488-494
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• 2018

To ensure food-safety of mushrooms from radioactive contamination, edible mushroom samples distributed in Gyeonggi province in Korea were collected according to species and country of origin. A total of 284 mushrooms, belonging to 10 species (Lentinula edodes, Pleurotus ostreatus, Pleurotus eryngii, Agaricus bisporus, Flammulina velutipes, Phellinus linteus, Inonotus Obliquus (Chaga), Auricularia auricula-judae, Ganoderma lucidum and Tricholoma matsutake) were subjected to radioactivity testing. The concentration of artificial radionuclides, 131I, 134Cs, and 137Cs, was analyzed using gamma-ray spectrometry. 131I and 134Cs were not detected more than MDA value from all samples. Among 204 domestic mushrooms, however, 137Cs were detected in 0.21~2.58 Bq/kg from six cases (3 Lentinula edodes, 1 Ganoderma lucidum and 2 Tricholoma matsutake), whereas 137Cs were detected in 0.21~53.79 Bq/kg from 38 cases (22 Inonotus Obliquus(Chaga), 14 Phellinus linteus, 1 Lentinula edodes and 1 Tricholoma matsutake) among 80 imported mushrooms. In addition, average concentration of 137Cs in 10 Chaga mushroom-processed products was more than twice as much as dried Chaga mushroom, and maximum concentration was 123.79 Bq/kg. Results suggest that radioactivity monitoring system for imported mushrooms and mushroom-processed products should be continuously intensified to secure food-safety in Korea.

• Geophysics and Geophysical Exploration
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• v.21 no.4
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• pp.255-261
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• 2018

The purpose of this study was to obtain a large amount of saline groundwater around coastal aquaculture farms. Thus, we have proposed a method for evaluating the potential amount of saline groundwater resources through the combined analysis of geophysical methods. Refraction seismic survey and electrical resistivity survey were conducted in the vicinity of fish farm at Hadong, Gyeongnam Province. As the result, the velocity of layer in the range of 900 ~ 2,400 m/s was found to be saltwater aquifer with high water content. Geological drilling investigation and analysis of soil samples also showed that the soil at study area was the same as the texture of sandy loam layer in agricultural radial collector wells installed by KRC (Korea Rural Community Corporation). Futhermore, the study area turned out to be quite possible to develop saline groundwater from the coastal shallow aquifer. Therefore, parallel analysis of refraction seismic surveys and electrical resistivity surveys at coastal area are expected to be very useful for the detection of the aquifer composed of sand and gravel layers with high porosity in sandy sedimentary layers along the coastal area.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.224-232
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• 2019

The movement of fish to the upper and the lower parts of a mountain stream was investigated based on the installation of specific types of structures within the stream. The results indicated that as the flow rate increases after a rain, the height of the drop in an open-type structure, such as a concrete box, is decreased so that the floating fishes, such as the Chinese minnow fish, move relatively easily from the upper to the lower parts and from the lower to the upper parts of the stream. In contrast, the fishes released from an upper point of a wall-type structure with <1 m, such as rocks drop works and stone masonry for stream-grade stabilization, were trapped in the lower part of the stream and, even after the rainy season, it was difficult for the fish to move from the lower to the upper parts of the stream. In particular, the barrier-type structures ${\geq}3m$ limit the movement of fish, even when there are few drainage holes at the lower end of the dam, and there is no space for the fishes to communicate with each other, even when the flow rate is high; therefore, although the fish are active, they are restricted to move according to the type and characteristics of the structures. When installing structures in a mountain stream, the height of the structure must be low enough to allow the fish to communicate with each other or an open-type structure must be installed. The fish habitat and water conditions within the stream must be considered when designing the type and height of the in-stream structures.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.278-280
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• 2019

Flow cytometer is one of the instrument that can measure various optical properties of a single cell or microparticle. These parameters including size, granularity, and fluorescence intensity are determined by the physical and optical interaction of the cells with excitation light source. However, users have some difficulties such as high cost, size of instrument, and limited fluorescence selectivity. In addition, abundant data is also unintentionally acquired even though user wants to have a single optical parameter. For these reasons, the use of flow cytometer is more challenging for researchers to apply their study. Therefore, the proposed study aims to develop a low-cost portable fluorescence acquisition system using a commercially available light-emitting diode and photodiode. It is designed by a 3D printer, and fluorescence selectivities are increased by changing of the light source / optical filter / detection sensor. Various number sets of fluorescently labeled cells were measured, and its feasibility was evaluated through the proposed system. As a result, acquried fluorescence intensities were proportional to the concentration of the cells and showed high linearity.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.37-43
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• 2021

Republic of Korea has many nuclear facilities in the country, and Democratic People's Republic of Korea(North Korea) locates in the surrounding country. Therefore, it is necessary to construct the target facility's nuclear forensic data in a preemptive response to the changing international situation. For this reason, this study suggests "signature" materials used to understand the origins and sources of nuclear and other radioactive materials, taking into account domestic nuclear facilities and the nuclear fuel cycle. In domestic, pressurized light water reactors and pressurized heavy water reactors are in operation, and enriched and natural uranium are used as fuels. In the front-end fuel cycle, the signature materials can be nature uranium and UF6 in the uranium enrichment process. The domestic back-end fuel cycle adopts a non-circulating cycle excluding the reprocessing process, and the primary signature material is spent nuclear fuel. According to IAEA recommendation, the importance of these materials as the signature and characteristic contents are suggested in this study. To prove the integrity of nuclear material and build a national nuclear forensics library, it is necessary to grasp the signature material and acquire the characteristic data considering the domestic nuclear facilities and the nuclear fuel cycle.