동진강 수계 농업용수 수질평가

한수곤,최정식,문영훈,엄미정,김갑철 한국환경농학회 2000 한국환경농학회지 Vol.19 No.2

동진강 수계의 수질현황을 파악하기 1994∼1998년 까지 4∼9월에 월 1회에 걸쳐 5개년간 조사한 결과를 요약하면 다음과 같다. 월별로는 빗물에 의한 희석효과로 7, 8월에 수질이 가장 양호하였으며, 4월이 다소 불량하였으나 수도생육 피해 한계농도에는 미치지 못하는 수준이었다. 지점별 수질현황은 생활하수 유입지인 정읍천과 지천의 폭이 좁은 원평천의 무기성분 함량이 높았으며 동진천 상류지역에서 가장 양호하였다. 연도별 현황은 '94년 이후 '95년까지는 수질이 악화되는 경향을 보였으나 '95년 이후로는 각 성분 함량이 낮았지는 등 점점 양호해지고 있으며 COD함량으로 볼 때 특히, 정읍천의 수질이 개선되고 있음을 알 수 있었다. 양이온과 음이온의 총당량온 4월에 가장 높았고 7, 8월에 가장 낮았으며 양이온/음이온의 당량비는 5월에 높았고 7월이 가장 낮았으며 지점에 따라서는 총당량은 정읍천, 원평천, 동진천 하류, 중류, 상류의 순위였으며 양이온/음이온 총당량 비율은 원평천이 상대적으로 작은 수치를 보였지만 지역간 큰 차이는 보이지 않았다. 수질 중 각 성분 상호간의 상관관계를 보면, 대개의 성분 상호간에 유의성이 높게 나타났으나, NO₄^--N는 대개의 성분과 유의성이 없었고, PO₄^(3-)-P도 COD, NH₄^+-N, NO₃^--N, SO₄^(2-)과는 유의성을 보이지 않았다. This study was conducted to monitor the irrigation water qualities along Dong-Jin river watershed. The water quality was surveyed at 6 sites from April to september during 1994∼1998. And the results were as follows : In July and August, water quality was better than that of any other months due to dilution with rainwater. Whereas, it became worse in April but it involved lower contents than limitted contents affected to the crop damage. Content of inorganic components was higher at Jeong-up and Won-pyeong stream. The reason for it that Jeong-up stream was deteriorated with sewage water from Jeong-up city, and Won-pyeong stream has narrow width. Water quality in upstream of Dong-Jin river, was evaluated best conditions in all sampling sites. For investigated period, water quality got worse from 1994 to 1995 but it was getting better to 1998 after 1995, especially at Jeong-up stream. The total equivalent of cation and anion was the highest at April through all months and at Jeong-up stream in sampling sites. Equivalent ratio of cation to anions(∑C/∑A) was higher at May than any other months and lower at Won-pyeong streams than any other sites. The value of most inorganic components was highly correlated with those of other components. But the value of NO₃^--N was not correlated with that of most components, and PO₄^(3-)-P was not correlated with COD, NH₄^+-N, NO₃^--N, SO₄^(2-_.

Rapid Consolidation of WC‑ZrSiO4 Hard Materials by Spark Plasma Sintering: Microstructure, Densification, and Mechanical Properties

Jeong‑Han Lee,Ik‑Hyun Oh,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

Densely consolidated WC-based hard materials with 5–20 vol% ZrSiO4was fabricated by spark plasma sintering at 1400 ℃ ata constant heating rate of 70 ℃/min−1. To achieve mechanical alloying of WC-ZrSiO4, planetary ball milling was carried outfor 12 h, during which the brittle-brittle components (WC-ZrSiO4) became fragmented and their particles became refined. Itwas observed that certain, specific, non-isothermal sintering kinetics, such as apparent activation energy, sintering exponents,and densification strain, affected the densification behavior. The evolution of phase structure from powder to compact wasfound to be related the lattice distortion and micro-strain in the basal planes of WC. By examining the mechanical propertiesof the samples, it was that the added zircon content leads to enhanced fracture toughness (12.9 MPa m1/2) owing to thepresence of WC-ZrSiO4 in the cemented carbide. In fact, the microcrack propagation of the fracture passed through zirconfrom a transgranular to a ductile component (fcc) where the crack tips could be absorbed.

Effect of Mechanical Alloying on the Microstructural Evolution of Al60Cr30Si10 Alloys Processed by Spark Plasma Sintering

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

In this study, Al, Cr and Si fine powders were alloyed by planetary ball milling to investigate their microstructural evolution,following their mechanical alloying behavior. The formation of Al(Cr) supersaturated solid solution by the Cr grainsembedded in Al-matrix, which contributed substitutional structure is discussed in relation to their structural evolution inaccordance with the distortion of a crystal lattice. The compacts of Al–Cr–Si alloys were prepared by rapid sintering withina short time by dense consolidation above the density of 99.9% as the formation of intermetallics, except in the case of thedistribution of single-phases induced by the Al-melting. The formation behavior of intermetallics was dominated by dependenceon the structures of the milled-powder and subsequent sintering temperature. To estimate the consolidated behaviorsof compacts, various approaches derived from TEM and XRD analysis were taken to obtain microstructural evidences ofthe inter-diffusion, following the presence of thermally stable intermetallics.

Influence of Phase Composition in TiAlSiN Hard Coatings on the Evolution of Structure and Mechanical Properties

Jeong‑Han Lee,Ik‑Hyun Oh,Jun‑Ho Jang,Ju‑Hun Kim,Sung‑Kil Hong,Hyun‑Kuk Park 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.3

The aim of this study is to investigate the structural evolution and mechanical properties of TiAlSiN coatings when processedby the arc ion plating method. To form a hard coating, Ti, Al, and Si powders were mechanically alloyed by planetary ballmilling; the powders were then densely compacted during a rapid sintering process into a ternary system coating, i.e. TiAlSi. The evolution of the structural phase from a powder to a compact material is dominated considerably by phase states suchas a supersaturated solid solution or intermetallic compounds. In the case of coating layers, the factors that determine thestructural evolution are associated with the phase stability of the nano-crystalline structure that in turn is associated withthe Ti/Al composition ratio. Motivated by this, we performed experiments to investigate the distribution of microstructures;the material’s binding energy, quantitative properties, transformation of crystal structure, and distribution of amorphous/crystalline were all recorded. In particular, the relationship between the physical and chemical properties during the coatingprocess is considered to be the dominant factor controlling the orientation and morphology of that zone (1, T, and 2). TheTiAlSiN coating layer was found to have hardness above 45 GPa and an adhesion above 100 N. In other words, understandingthe evolution and structure of TiAlSin helped us to produce a material with excellent properties that can be used as a hardcoating. Specifically, these properties were induced by a grain refinement of the nano-crystalline structure that correspondsto an increase in the silicon nitride contents.

강원도 사북-고한 지역의 석탄광 폐석에 대한 물리적, 역학적 특성 연구

임한욱,정윤영,목진호,김종훈,김재동,신동오 강원대학교 석재복합신소재제품연구센터 1996 석재연 논문집 Vol.1 No.-

석탄광 폐석의 건설용 골재로서 활용 가능성을 검토하기 위하여 폐석의 주요 구성암석인 사암, 사질혈암, 혈암, 탄질혈암을 대상으로 기초물성실험, 역학적 실험 및 골재원 특성 실험을 실시하였다. 시험결과치의 평균값을 기준으로 할 때 사암, 사질혈암, 혈암은 골재로서 활용이 가능하나, 실험치의 분산도가 심하여 활용가능 폐석과 불가능한 폐석이 혼재되 있음을 확인하였다. 반면에 탄질혈암은 골재원 특성이 가능하나 강도등 물성에서는 사용이 곤란한 것으로 판단되었다. 따라서 앞으로 폐석중 활용가능한 사암, 사질혈암 및 혈암을 효율적으로 분급하는 방안과 금번에 실시하지 못한 골재의 알카리 반응시험 등이 추가로 보완되었으면 한다. An experimental program was undertaken to test rock wastes from coal mines, for use as a new source of aggregate. Physical and mechanical properties, required for aggregate materials, of major constituents of rock wastes including sandstones, sandy shales, shales, and coal shales, were measured in the laboratory. Test results showed that the sandstones, sandy shales and shales tested in this study might possibly be used for construction aggregates, the highly scattered test data indicated considerable proportion of unusable rocks. In case of coal shales, the aggregate characteristics were generally adoptable but some physical properties such as rock strength were lower than required. In conclusion, it is suggested that an effective procedure for sorting the rock wastes, and additional tests such as alkali-aggregate reaction should be supplemented.

과도 절삭에서의 절삭 공정 시뮬레이션

고정훈,조동우,윤원수,김주한 한국공작기계학회 2001 한국공작기계학회 춘계학술대회논문집 Vol.2001 No.-

In most of the existing mechanistic models, the cutting process simulation is often restricted to a single path machining operation under a fixed cutting condition. Complex cutting processes such as die or mold manufacturing, however, are performed under two- or three-dimensional multiple tool paths. Since the tool paths in CNC machining are composed of line and arc segments, transient cuts are frequently occured due to the multiple paths. Even in steady cuts, the width of cut is varied with each segment. In this regard, this paper deals with the development of process simulation system for transient cuts, where continuously changing cutting configuration is computed, and then the cutting forces are predicted.

생쥐모델에서의 망막모세포종 안구 자기공명분광법과 병리소견 : 초기경험

김동훈,김일중,양재한,김정훈,유영석,이봉재 朝鮮大學校 附設 醫學硏究所 2007 The Medical Journal of Chosun University Vol.32 No.1

Purpose: To show various MR spectroscopy and correlated pathologic images of retinoblastoma in nude mouse with a new human retinoblastom cell line (SNUOT-Rbl) which innoculated into intravitreous cavity. Materials and Methods: The established cell line was innoculated into mtravitreous cavity of 14 eyeballs of 7 mice and a transplanted retinoblastoma was examed for 1 month. Tl-weighted image (T1WI), T2-weihgted image (T2WI), and MR spectroscopy were obtained with 1.5 Tesla MRI (Magnetom Vision, Siemens, Erlangen, Germany) and 4.7 Tesla MRI (Bruker, Medizintechnik GmbH, Karlsruhe-Ettlingen, Germany). After scanning, eyeballs were extracted and hematoxylin & eosin stained specimens were examined with the microscope. We compared MR spectroscopy with pathologic findings and evaluated characters of tumors. Results: Innoculated cells into eyeball of mice grew retinoblastoma (8/14, 57%). Eyeball with retinoblastoma protruded externally and showed focal hemorrhage. Tumors showed low (n=3), iso (n=4), high (n=1) signal intensity on TIWI, low (n=5), iso (n=1), high (n=2) signal intensity on T2WI, and well enhancement (n=8) with contrast, Involvement of optic nerve was suspected by MRI and confirmed by pathology (n=1). Conclusion: We could demonstrate MR spectroscopy of transplanted retinoblastoma by new tumor cell line in vivo. This imaging technique facilitate molecular imaging investigation of retinoblastoma.

태양 추적 장치를 갖는 집광 시스템의 집열 특성

이용훈,최석천,지명국,이상철,정효민,정한식 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-

The purpose of this research is to obtain the heat transfer characteristics of the absorber type solar collector. This new system moving by time and degree. The second system had the solar tracking system. The x-y axis were designed at intervals of 0.33˚/min and 0.16˚/min respectively. In this system the absorber specification was 1OOLX80Φ1.4t. This experiment was conducted from July to August. 2002. The temperature of solar collector was reached about mean temperature 250℃.

특수학급의 이러닝 활용 실태와 요구 조사

우정한,김영걸,신재훈 국립특수교육원 2006 특수교육연구 Vol.13 No.2

특수교육 분야에서는 이러닝을 통하여 장애학생 교육 서비스의 양적·질적 발전을 위한 다각적인 노력을 모색하고 있다. 그러나 특수교육 현장의 실제 활용 실태와 이와 관련된 구체적인 요구에 대한 기초연구가 부족하여 효과적인 이러닝 실행을 위한 지원 방향을 수립하지 못하고 있다. 따라서 본 연구는 특수학급 교사들을 대상으로 설문조사를 실시하여 특수학급의 이러닝 관련 환경과 활용 실태를 탐색하였고, 특수학급구성원들이 가지고 있는 이러닝 실행과 관련된 요구를 밝혔으며, 이를 바탕으로 특수학급에서 이러닝을 효과적으로 운영하고 실행하기 위한 시사점을 제시하였다. E-learning is learning that utilizes contents crafted based on multimedia and hyper media via diverse information technologies. It enables teaching and learning to allow disabled students to utilize contents crafted with diverse latest techniques, thereby expanding the forum of learning. Thus, the special education area is making diverse efforts to achieve quantitative and qualitative development of educational services for disabled students through e-learning. However, since basic research is lacking with regard to the actual utilization status of e-learning and corresponding needs in special education, an appropriate support direction for performing e-learning cannot be determined. Against such a backdrop, this research surveyed the e-learning status and needs in special classes. Likewise, it surveyed the environment and utilization status of computers, software, and assistive technology that special classes in 'B' and 'D' city owned for e-learning. It also surveyed hardware and software requirements for effectively performing e-learning in special classes.

개에서 이중 결찰법을 통한 동맥관 개존증의 완치 예

윤헌영,정순욱,박희명,박철,정만복,김준영,한현정,황민,노병국,박상혁,장하영,박정윤 한국임상수의학회 2004 한국임상수의학회지 Vol.21 No.1

A ten months old, female Yorkshire terrier weighing 2.88 kg referred to veterinary teaching hospital of college of veterinary medicine, Konkuk University because of syncope, cough and dyspnea. First hematological and serum chemical test revealed thrombocytopenia, mild anemia, and increase of concentration of ALP (195 U/L). On 57 days later, second hematological and serum chemical test revealed polycythemia, increase of concentration of ALP (211 U/L), and Tchol (387 mg/dl). Right atrium enlargement, main pulmonary artery bulge and cardiomegaly (VHS = 11.5) were observed in radiographic findings. Ultrasonographic images showed both right and left ventricular dilation and turbulent flow between the descending aorta and the main pulmonary artery in color Doppler imaging. ECG showed left ventricular enlargement, SA block, and electrical alternant. Thoracotomy was performed through left fourth intercostal incision under isoflurane anesthesia. Patent ductus arteriosus was double ligated with 1-0 silk. Cough and dyspnea disappeared on 5 days after operation. Turbulent flow was not found in color doppler imaging of ultrasonography on 10 days after operation. Ten months later after the operation, syncope could not exist any more.