• Journal of the Society of Disaster Information
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• v.13 no.3
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• pp.305-312
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• 2017

In our society, the advanced, advanced, and information industries have continued to grow and now live in the era of the fourth industrial revolution. As the industry develops, the load of the users has also increased so much that it is deepened by the energy shortage phenomenon and the construction of additional energy facilities is required. Therefore, energy plant construction work is being actively carried out in the coastal area. In particular, it is common to build a plant in the ground by filling the coast with soil in other regions, reflecting the fact that Korea is lacking in the country when constructing power plants, gas and petrochemical plants. Current domestic grounding designs are designed or constructed to suit only the use of grounding resistors based on the electrical equipment design technical standards. However, in the case of a plant facility constructed in the untested buried soil, when the lightning current and the abnormal current are inputted, the facility operator or the user due to the elevation of the ground potential is seriously exposed to the risk of electric shock disaster. In this paper, we analyze the ground resistivity of the landfilled soil and use a computer program (CDEGS) based on KS C IEC 61936-1, We analyze the contact voltage and stratification voltage and propose a grounding design optimized for plant installation.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.165-165
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• 2017

지난 수 십 년 동안, 전 세계적으로 자원의 소비가 급격히 증가하게 되면서 최근 자원 고갈은 물론 환경오염이 커다란 이슈로 문제가 되고 있다. 이에 따라 재료 관련 분야에 있어서는 보다 효율적이고 친환경적인 방법으로 자원을 활용해야 된다는 필요성이 대두되었고 이와 같은 관점에서 목적하는 성분이 우수하고 환경 친화적인 표면처리 재료 개발연구가 활발하게 진행되고 있는 실정이다. 그 중 플라즈마 전해 산화(Plasma Electrolytic Oxidation, PEO)는 알루미늄, 마그네슘 등의 경금속의 경도를 향상시키고 높은 내마모성, 내식성을 갖게 하는 표면처리로써 그 관심이 증가하고 있다. 이 플라즈마 전해 산화는 일반적으로 공정비용 대비 효과적이고 환경 친화적이며 코팅 성능 면에서 우수하다고 알려져 있다. 이러한 고유한 특성으로 인해 플라즈마 전해 산화 코팅은 최근 몇 년 동안 기계, 자동차, 우주항공, 의학 및 전기 산업 등의 분야에서 그 적용이 점차 증가하고 있는 상황이다. 한편, 플라즈마 전해 산화 코팅을 하는 모재들의 경우 부동태 산화피막을 용이하게 형성할 수 있는 특성의 모재에 한정되고 있어서 그 응용확대에 한계가 있는 것이 사실이다. 따라서 본 연구에서는 플라즈마 전해 산화법을 사용하여 용융알루미늄도금 강판 상에 산화피막 형성을 시도하였다. 전원공급 장치의 양극은 전해질 속에 잠겨있는 작동전극에 연결하고 음극은 대전극 역할을 하는 스테인레스강 전해질 용기에 연결되었다. 전해질은 Sodium Aluminate 및 기타 첨가제를 함유한 것을 사용하였고 온도는 열교환기를 사용하여 $30^{\circ}C$ 이하로 유지되었다. 또한 여기서 전류밀도는 $5{\sim}10A/dm^2$, 실험 주파수는 700Hz, Duty cycle은 30 및 90%의 각 조건에서 공정처리 시간을 각각 30분 및 60분 동안 진행하였다. 이와 같은 조건에서 형성한 막들에 대해서는 주사형전자현미경(SEM)을 이용하여 코팅 막의 표면 및 단면의 모폴로지를 관찰하였음은 물론 EDS 및 XRD 측정을 통하여 원소조성분포 및 결정구조를 각각 분석하였다. 또한 이 코팅 막들에 대한 내식성은 5% 염수분무 환경 중 노출시험(Salt spray test), 3% NaCl 용액에서의 침지 시험 및 전기화학적 동전위 양극분극(Potentiodynamic Polarization) 시험을 진행하여 평가하였다. 이상의 실험결과에 의하면, 제작조건별 플라즈마 전해 산화 코팅 막의 모폴로지 및 결정구조가 상이하게 나타나는 것을 알 수 있었다. 코팅 막의 모폴로지 관찰 결과, 공정 시간에 비례하여 표면에 존재하는 원형 기공의 수는 감소하였으나 그 크기가 커지고 크레이터의 직경 또한 커진 것이 확인되었다. 이 기공은 마이크로 방전에 의해 형성된다고 알려져 있는데 공정 시간이 증가함에 따라 코팅 두께가 점차 증가하여 마이크로 방전의 빈도수가 줄어들고 그 강도는 증가하게 되어 기공 크기가 증가한 것으로 사료된다. 또한 공정시간이 긴 시편에서 표면에 크랙이 다수 존재하는 것으로 확인되었다. 이것은 방전에 의해 고온이 된 소재가 차가운 전해질과 만나게 되어 생긴 큰 온도구배로 인해 강한 열응력이 발생하여 균열을 초래한 것으로 보인다. 조성원소 분석 결과 원형 기공 주변의 크레이터 영역에는 알루미늄이 풍부하였으며 그 주변에 결절상을 갖는 구조에서는 전해질 성분의 원소가 포함되어 있는 것이 확인되었다. 이러한 코팅 막의 표면 특성은 내식성에 영향을 주게 된 원인으로 사료된다. 동전위 분극측정 결과에 의하면 플라즈마 전해 산화 공정 시간이 길어질수록 부식전류밀도가 증가하였다. 이것은 공정시간이 길어짐에 따라 강한 방전이 발생하여 기공의 크기가 증가하고 크랙이 발생하게 되면서 내식성이 저하된 것으로 판단된다. 종합적으로 재료특성 분석 및 내식성 평가를 분석한 결과, 플라즈마 전해 산화의 공정 시간이 너무 길게 되면 오히려 내식성은 저하되는 것이 확인되었다. 이상의 연구를 통하여 고내식 특성을 갖는 플라즈마 전해 산화 막의 유효성을 확인하였으며 용융알루미늄강판 상에 실시한 플라즈마 전해 산화 처리에 대한 기초적인 응용 지침을 제시할 수 있을 것으로 사료된다.

• Journal of Sericultural and Entomological Science
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• v.24 no.2
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• pp.55-72
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• 1983

These studies were done to find out any difference, ultrastructural, physical or chemical, between the shells of diapausing and non-diapausing eggs of the silkworm, Bombyx mori L. 1. From the electron-microscopic observation, the egg shells have four distinctive layers. In addition to the four layers, the shells in the diapausing eggs has another layer with low electron density on its surface. 2. The permeability of the egg shell to hydrochloride was much lower in diapausing egg than in non-diapausing egg. Also the permeability changed in the opposite directions with the egg age: the diapausing eggs decreased while non-diapausing ones increased. 3. The permeability increased when the diapausing egg shell was treated with HCl. When they were treated with ether, however, the increase in permeability was much smaller. It seems there was an ether soluble material involved in the content of the egg shell. 4. The diapausing eggs were also much more resistant to desiccation than the non-diapausing ones. The former, when treated with HCl or chilling, became less resistant to desiccation. 5. The positive histochemical response of the egg shell to PAS-Alcian blue and protein stainings suggests presence of abundant proteins and carbohydrates in the egg shell. On the other hand, the staining response to lipid was more positive in the inner layers than in the outer layer of the shell. 6. The egg shell adhesives seems to be mucopolysaccharides produced by colleterial glands, since the oviposited eggs showed a positive responses to carbohydrate and negative to lipid-staining chemicals, but not the mature oocytes in the ovarioles. 7. There were two bands on the electrophoretic pattern of the SH proteins extracted from the egg shells both in the diapausing egg and non-diapausing one: a slow moving major component and a fast moving minor one. However, the electrophoretic mobility showed a difference in the minor components between them. It is evident that the fast moving minor one of non-diapausing egg ran a little further than that of diapausing egg. 8. In amino acids analysis, no significant differences were found in their composition between diapausing and non-diapausing egg and SH proteins contain relatively more glycine and less cystine.

• Journal of Radiation Protection and Research
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• v.23 no.2
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• pp.89-96
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• 1998

To assess the radioprotective effects of follicle stimulating hormone (FSH) on ovarian follicles, 3 week-old female mice were irradiated with 8.33 Gy of ${\gamma}$-ray (group R) and followed by 5 IU ip-injection of FSH (group RF). For control groups, 5 IU of saline (group C) or 5 IU of FSH (group F) was ip-injected. Ovaries were collected 0h, 6h, 12h, 14, 2d, 4d, and 8d after irradiation or saline/FSH injection, and followed by fixation in neutral buffered formalin for routine histochemistry. Immunohistochemistry was used to assess the status of follicles and DNA fragmentation was analyzed by agarose gel electrophoresis for total DNA. Staining specific for apoptotic follicles showed high intensity at 6h and 12h in group R and RF On the other hand, staining specific for proliferating follicles showed noticeably high intensity at 8d in group R and Rf. DNA fragmentation of 185bp increased with time in all experimental groups. Especially 370bp appeared at 6h in group R, then disappeared after 1d. In case of group RF, it appeared at 12h and disappeared after 1d. From the above results, the irradiated antral follicles become completely disappeared from 4d to 8d, and then new follicles started to grow again at 8d. FSH had delaying or suppressing effects on follicular atresia after irradiation. In addition, it became clear that radiation-induced follicular atresia was mediated by granulosa cell apoptosis.

• Polymer(Korea)
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• v.29 no.4
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• pp.403-407
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• 2005

In this work, the solid polymer electrolyte (SPE) composites, which are composed of poly(ethylene oxide) (PEO), mesoporous mobil crystalline material-41 (MCM-41), and lithium salt, are prepared in order to investigate the influence of MCM-41 contents on the ionic conductivity of the composites. The crystallinity of the SPE composites was evaluated using differential scanning calorimeter (DSC) and X-ray diffraction (XRD). The ionic conductivity of the SPE composites was measured by the frequency response analyzer (FRA). As a result, the addition of MCM-41 into the polymeric mixture prohibited the growth of PEO crystalline domain due to the mesoporous structures of the MCM-41. The $P(EO)_{16}LiClO_4$/MCM-41 electrolytes show an increased ion conductivity as a function of MCM-41 content up to 8 $wt\%$ and a slightly decreased conductivity over 8 $wt\%$. These ion conductivity characteristics are dependent on a change of polymer crystallinity in the presence of MCM-41 system.

• Journal of the Korean Electrochemical Society
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• v.24 no.3
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• pp.52-64
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• 2021

The effect of Fe and BO₃ doping on structure, thermal, and electrical properties of Li_1+xFe_xTi_2-x(PO₄)_3-y(BO₃)_y (x = 0.2, 0.5)-based glass and glass ceramics was investigated. In addition, their crystallization behavior during sintering and ionic conductivity were also investigated in terms of sintering temperature. FT-IR and XPS results indicated that Fe²⁺ and Fe³⁺ ions in Li_1+xFe_xTi_2-x(PO₄)_3-y(BO₃)_y glass worked as a network modifier (FeO₆ octahedra) and also as a network former (FeO₄ tetrahedra). In the case of the glass with low substitution of BO₃, boron formed (PB)O₄ network structure, while boron preferred BO₃ triangles or B₃O₃ boroxol rings with increasing the BO₃ content owing to boic oxide anomaly, which can result in an increased non-bridging oxygen. The glass transition temperature (GTT) and crystallization temperature (CT) was lowered as the BO₃ substitution was increased, while Fe²⁺ lowered the GTT and raised the CT. The ionic conductivity of Li_1+xFe_xTi_2-x(PO₄)_3-y(BO₃)_y glass ceramics were 8.85×10^-4 and 1.38×10^-4S/cm for x = 0.2 and 0.5, respectively. The oxidation state of doped Fe and boric oxide anomaly were due to the enhanced lithium ion conductivity of glass ceramics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.247-251
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• 2004

반도체 소자의 제조에 있어 실리콘 표면에 성장한 자연산화막을 제거하기 위해 일반적으로 습식 세정 기술이 이용되어 왔다. 하지만 소자의 최소 선폭(design rule)이 nano급으로 고집적화 됨에 따라 contact hole 바닥의 자연산화막을 깨끗이 제거하는데 있어서 그 한계를 나타나고 있다. 이에 대한 효과적인 대안 공정으로 가스 건식 세정 기술이 연구되고 있다. 본 논문에서는 한 번에 50매 이상의 웨이퍼를 처리함으로써 생산성 측면에서 월등한 배치식 설비에서 원거리 플라즈마(remote plasma) 장치에서 2.450Hz의 마이크로웨이브(${\mu}$-wave)에 의해 형성시킨 수소라디칼과 $NF_3$ 가스를 이용하여 실리콘에 결함을 주지 않고 자연산화막을 선택적으로 제거하는 공정에 대해 고찰하였다. AFM을 이용한 표면분석, TEM을 이용한 물성분석, 그리고 ToF-SIMS 및 XPS를 이용한 화학 분석을 습식 및 건식 세정을 비교 평가한 결과, 건식 세정 공정이 실리콘 표면에 결함을 주지 않고 자연산화막을 제거 할 수 있음을 확인하였다. 산화막$(SiO_2)$, 질화막$(Si_3N_4)$, 그리고 다결정 실리콘(Poly-Si) 등의 각 막질별 식각 특성을 고찰하였으며, $NH_3$의 캐리어 가스인 $N_2$의 주입량을 조절함으로써 수소라디칼 형성 효율의 개선이 가능하였으며, 이로부터 게이트와 소스/드레인 사이를 절연하기 위해 이용되는 질화막의 식각 선택비를 2배 정도 개선할 수 있었다. nano급 소자에 실장하여 평가한 결과에서 불산(HF)에 의한 습식 세정 방식에 비하여 약 $20{\sim}50%$ 정도의 contact 저항 감소 효과가 있음이 확인되었다.두 소자 모두 $40mA/cm^2$ 에서 이상적인 화이트 발란스와 같은(0.33,0.33)의 색좌표를 보였다.epsilon}_0=1345$의 빼어난 압전 및 유전특성과 $330^{\circ}C$의 높은 $T_c$를 보였고 그 조성의 vibration velocity는 약4.5 m/s로 나타났다.한 관심이 높아지고 있다. 그러나 고 자장 영상에서의 rf field 에 의한 SAR 증가는 중요한 제한 요소로 부각되고 있다. 나선주사영상은 SAR 문제가 근원적으로 발생하지 않고, EPI에 비하여 하드웨어 요구 조건이 낮아 고 자장에서의 고속영상방법으로 적합하다. 본 논문에서는 고차 shimming 을 통하여 불균일도를 개선하고, single shot 과 interleaving 을 적용한 multi-shot 나선주사영상 기법으로 $100{\times}100$에서 $256{\times}256$의 고해상도 영상을 얻어 고 자장에서 초고속영상기법으로 다양한 적용 가능성을 보였다. 연구에서 연구된 $[^{18}F]F_2$가스는 친핵성 치환반응으로 방사성동위원소를 도입하기 어려운 다양한 방사성의 약품개발에 유용하게 이용될 수 있을 것이다.었으나 움직임 보정 후 영상을 이용하여 비교한 경우, 결합능 변화가 선조체 영역에서 국한되어 나타나며 그 유의성이 움직임 보정 전에 비하여 낮음을 알 수 있었다. 결론: 뇌활성화 과제 수행시에 동반되는 피험자의 머리 움직임에 의하여 도파민 유리가 과대평가되었으며 이는 이 연구에서 제안한 영상정합을 이용한 움직임 보정기법에 의해서 개선되었다. 답이 없는 문제, 문제 만들기, 일반화가 가능한 문제 등으로 보고, 수학적 창의성 중 특히 확산적 사고에 초점을 맞추어 개방형 문제가 확

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.14-30
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• 2007

The purpose of this study was to evaluate trophic conditions of various Korean reservoirs using Trophic State Index (TSI) and predict the reservoir conditions by empirical models. The water quality dataset (2000, 2001) used here were obtained from the Ministry of Environment, Korea. The water quality, based on multi-parameters of dissolved oxygen (DO), biological oxygen demand (BOD), chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN), suspended solid (SS), Secchi depth (SD), chlorophyll-${\alpha}$ (CHL), and conductivity largely varied depending on the sampling watersheds and seasons. In general, trophic conditions declined along the longitudinal axis of headwater-to-the dam and the largest seasonal variations occurred during the summer monsoon of July-August. Major inputs of TP occurred during the monsoon (r=0.656, p=0.002) and this pattern was similar to solid dynamics of SS (r=0.678, p<0.001). Trophic parameters including CHL, TP, SD, and TN were employed to evaluate how the water systems varies with season. Trophic State Index (TSI, Carlson, 1977), based on TSI (CHL), TSI (TP), and TSI (SD), ranged from mesotrophic to eutrophic. However, the trophic state, based on TSI (TN), indicated eutrophic-hypereutrophic conditions in the entire reservoirs, regardless of the seasons, indicating a N-rich system. Overall, nutrient data showed that phosphorus was a primary factor regulating the trophic state. The relationships between CHL (eutrophication index) vs. trophic parameters (TN, TP, and SD) were analysed to develop empirical models which can predict the trophic status. Regression analyses of log-transformed seasonal CHL against TP showed that the value of $R^2$ was 0.31 (p=0.017) in the premonsoon but was 0.69 (p<0.001) during the postmonsoon, indicating a greater algal response to the phosphorus during the postmonsoon. In contrast, SD had reverse relation with TP, CHL during all season. TN had weak relations with CHL during all seasons. Overall, data suggest that TP seems to be a good predictor for algal biomass, estimated by CHL, as shown in the empirical models.

• Korean Journal of Poultry Science
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• v.34 no.4
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• pp.237-243
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• 2007

The objective of this experiment was to investigate the feeding influence of Prunus memu by-products (PMB) on productivity, blood composition, meat quality and intestinal microflora in semi-broiler chicks. Four hundred one day old chicks(Hanhyup 3) were raised in the floor pen with five treatments(0, 0.5, 1.0 2.0 3.0%) of four replicate for ten weeks. Basal diets contained 3,000, 3,100, 3,100, 3,200 kcal/kg ME and 22, 21, 19, 17% CP, respectively. There were no different performance for the first two weeks, but showed significantly different weight gain, feed intake in PMB 2.0, 3.0% addition treatments compared with control from three to five weeks of age. Weight gain of birds fed 2.0% PMB was significantly higher from nine to 10 weeks of age than control(P<0.05). Total weight gain tended to increase in PMB 1.0, 2.0, 3.0% addition treatments. Feed intake also showed increase in PMB 2.0, 3.0% addition treatments, but there were no different feed conversion. Total protein, albumin, cholesterol, neutral fat, glucose was significantly decreased in PMB 0.5% addition treatments compared with control. There were no different physico-chemical characteristics in breast meat. The number of yeast was significantly improved in PMB 3.0% compared with control(P<0.05), but found no difference in number of E. coli between control and PMB treatments. ND titer of birds fed PMB was not statistically different, but tended to decrease as dietary PMB increased. As the result of this experiment, PMB would be available as a feed additives in semi-broiler chicks.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.15 no.1
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• pp.91-100
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• 2004

Objectives：The effects of repeated maternal separation on the expression of glucocorticoid receptor (GR) and cyclooxygenase-2(COX-2) in the hippocampus of rat pups at preweanling stage were evaluated. Methods：The experimental, Repeated Maternal Separation group(N=4) was separated from the mother for four hours a day over a period of ten days beginning with postnatal day 4. The Control group(N=4), on the other hand, did not separated from the mother at all. GR and COX-2 expression in the hippocampus was examined by immunohistochemistry on postnatal day 14. Results：It was determined that the number of GR-immunopositive cells in the dentate gyrus of the hippocampus was significantly increased in the Repeated Maternal Separation group. The numbers of COX-2-immunopositive cells in the CA1 and CA3 were also significantly higher in the Repeated Maternal Separation group. Conclusion：These results suggest that maternal separation may be a significant developmental stress that induces GR and COX-2 expression in the hippocampus of developing pups.