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      • 중첩 방전을 이용한 CO₂레이저의 동작 특성 : 다중펄스 중첩을 이용한 long 펄스형 CO₂레이저의 펄스 형상 제어 Pulse shape control of pulse CO₂laser using multiple-pulse superposition

        정현주,김근용,정용호,정종한,송건주,김희제 부산대학교 생산기술연구소 2001 生産技術硏究所論文集 Vol.60 No.-

        본 연구에서는 PIC 원 칩 마이크로 프로세서 기술을 접목시켜, 저전압 측에서 2단 또는 3단의 회로를 능동적으로 중첩시킴으로써, 다양한 펄스폭을 가지는 고전압의 펄스형상을 만들었다. 이렇게 만들어진 다양한 중첩펄스를 현재 산업용 및 의료용으로 많이 사용되고 있는 CO2 레이저에 적용하여 각 단의 스위치의 트리거 지연시간에 따른 레이저 빔의 출력 특성을 고찰하였다. 그 결과 다양한 펄스폭을 가지는 레이저 빔을 얻을수가 있었고 특히, 3단 중첩회로에서 스위칭 지연 시간을 변화시킴에 따라 얻어진 레이저 펄스폭은 최소 약 4ms였고 최대 약 10ms였다. In this study, a variable pulse length, high duty cycle Pulse Forming Network(PFN) is constructed by time sequence. The power supply for this experiment consists of three switching circuits. Each switching circuit uses 2 mesh PFN, a charging circuit, a HV leakage transformer, and bridge rectifier on each transformer secondary. The PFN elements operate at low voltage and drive the primary of HV leakage transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence. We investigated laser pulse width of pulsed CO2 laser as various delay time among three switching circuits. As a result, we can obtain various laser pulse width from about 4 to 10ms.

      • 쥐노래미 Hexagrammos otakii의 난소 발달단계에 따른 간세포의 활성변화

        정의영,강희웅,이근우 한국어류학회 2002 韓國魚類學會誌 Vol.14 No.2

        암컷 쥐노래미(Hexagrammos otakii)의 생식소중량지수(GSI)는 9월에 증가되기 시작하여 11월에 최대에 도달하였다. 쥐노래미의 생식주기는 연속적인 5단계로 나눌 수 있었다: 성장전기(7월), 성장후기(7~8월), 성숙기(9~10월), 완숙 및 산란기(9~12월), 회복 및 휴지기(12~6월). 간중량지수(HSI)의 월변화는 GSI변화와 유사한 경향을 보였다. 성장전기에 다량의 지방적과 글리코겐 입자들이 간세포내에 존재하였다. 특히, 이 시기에 간세포는 헤마톡실린에 약하게 염색되었다. 성장후기부터 성숙기에 간세포의 크기는 증대되었으며 간세포질내 글리코겐과 지방적들의 양은 감소된 반면, 호염기성 물질 축적이 증가하였다. 산란기부터 회복 및 휴지기에는 간세포내에 호염기성 물질 축적이 감소된 반면, 다량의 지방적과 글리코겐입자가 축적되었다. 간세포내의 총단백질, 총지질 및 글리코겐함량(%)의 최대값은 각각 9월(성숙기), 7월(성장전기), 3월(휴지기)에 나타났다. The GSI in the female greenling Hexagrammos otakii, began to increase in September and reached a maximum in November. The reproductive cycle of the greenling can be divided into five successive stage: early-growing stage(July), late- growing stage(July to August), mature stage(September to October), ripe-and-spent stages(September to December), and recovery-and-resting stages(December to June). Monthly changes in the HSI showed a similar pattern with those of the GSI. In the early- growing stage, a lot of lipid droplets, and glycogen particles were present in the cytoplasm of hepatocytes. Especially, the cytoplasm of hepatocytes were weakly stained with hematoxylin. In the late- growing to mature stage, hepatocytes became large, and the amount of glycogen and lipid droplets in hepatocytes gradually decreased, while basophilic substance increased. In the spawning to recovery-and-resting stages, basophilic substances decreased in the cytoplasm of hepatocytes. However, lots of lipid droplets and glycogen were stored in the hepatocytes. The maxium total protein, lipid and glycogen contents(%) in the hepatocytes appeared in September(mature stage), July(early-growing stage) and March(resting stage), respectively.

      • KCI등재

        구조용 데크플레이트를 사용한 연속 합성슬래브 시스템의 모멘트 재분배 및 소성회전능력

        정헌수,은희창,양근혁 대한건축학회 2005 大韓建築學會論文集 : 構造系 Vol.21 No.2

        The objective of this study is to evaluate the moment redistribution and plastic rotation of continuous one-way composite slabs reinforced with structural steel decking. A total of 8 two-span continuous slabs with fixed-ends were tested and compared with limit analysis approaches. Theoretical moment capacity and curvature for section subjected to positive or negative moment were calculated by section laminae method. Test results showed that flexural behavior and rotation were greatly influenced by the amount of top bar in negative moment region. Also, the welded wire fabric used as top bar in negative moment region could result in decreasing total load capacity of slabs due to impairing moment redistribution. The predictions, maximum load and plastic rotation capacity, obtained from proposed analysis method were in good agreement with the test results.

      • KCI등재

        골프장의 잔디 토양에서 살균제 Tolclofosmethyl의 분해

        정근욱,우선희,김흥태,사동민,김영기,홍순달,김재정,이재구 한국환경농학회 2004 한국환경농학회지 Vol.23 No.3

        Tolclofosmethyl (TCFM) is heavily and annually applied to the turf soils of most golf courses in Gyeongju to control the fungi known to cause the disease brown patch. The soil samples used for the experiment was collected three weeks after the annual application at the end of May in the year 2002. The preliminary results obtained from this study demonstrated that the repeated field annual applications of TCFM to the turf soils of a golf course located in Gyeongju city in the southern area of Korea showed the enhanced degradation of the parent compound TCFM, especially in the surface (0~15 cm) soil rather than the shallow subsurface (15~30 cm) and deep subsurface (30~45 cm) soils, compared to the corresponding surface (0~15 cm) and shallow and deep subsurface (15~30 cm and 30~45 cm) soils of the untreated plot. It appears that microorganisms in the soil may be involved in the enhanced degradation of TCFM.

      • 개구부 폭과 깊이 변화에 따른 철근콘크리트 깊은 보의 파괴모드 및 내력 평가에 관한 연구

        양근혁,이영호,은희창,정헌수 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

        The purpose of this study is to investigate the failure mode and the shear strength of reinforced concrete deep beams with rectangular openings. Fourteen deep beams which shear span-to-depth ratio(a/h) is 0.5 were tested and an equation to predict the ultimate shear strength of deep beams with rectangular openings was established by the test results.

      • KCI등재후보

        류마티스 관절염 환자에서 발생한 Mycobacterium intracellulare에 의한 관절염 1예

        박근우,권현희,정승혜,김경찬,최정윤,이영환 대한감염학회 2007 감염과 화학요법 Vol.39 No.1

        비정형 항산균에 의한 근골격계 감염은 매우 드물며, 진단이 지연되는 경우가 많다. 저자들은 류마티스 관절염환자에서 수차례 스테로이드 주사 후에 생긴 M. intracellulare에 의한 관절염을 진단하고 수술적 치료없이 약물 치료만으로 좋은 결과를 보인 예를 경험하였기에 보고하는 바이다. Nontuberculous mycobacteria are ubiquitous organisms that are frequently present in the water, soil and animal reservoirs. Nontuberculous mycobacterial infections of the musculoskeletal system are rare and usually associated with predisposing factors, such as prior joint disease, trauma, use of intraarticular or oral corticosteroids, or an immunocompromised state. A sixty five-year-old patient with rheumatoid arthritis was hospitalized due to swelling on the left wrist. M. intracellulare was cultured from the aspirated joint fluid. The patient was successfully treated with clarithromycin, ethambutol, and rifampin. We report this case with review, emphasizing high suspicion for nontuberculous mycobacterial infection in patients with predisposing risk factors.

      • 상계치 이론을 이용한 장방형 개구부를 갖는 철근콘크리트 깊은 보의 전단내력 평가

        양근혁,이영호,은희창,정헌수 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2(구조계)

        The purpose of this study is to evaluate the failure plane and the shear capacity of reinforced concrete deep beams with rectangular openings using upper bound theorem. A numerical optimization procedure programmed to obtain the minimum value of the shear capacity by adjusting the position of the instantaneous center according to various potential failure planes. The predictions obtained from the proposed method are in good agreement with experimental results.

      • 할로겐화은 막전극에 관한 연구

        金禎姬,李根植 淑明女子大學校 1980 論文集 Vol.20 No.-

        AgCl/PVC·THF, AgBr/PVC·THF 막전극의 은이온농도에 대한 감응은 10^-1M∼10^-6M농도범위에서 거의 직선적이고 기울기가 Nernstian Slope에 잘 일치하였다. 막전극은 견고하고 장시간 안전하게 사용할 수 있는 특성을 가졌다. 이 전극은 Hg^2+을 제외한 다른 양이온에 대해서는 거의 감응하지 않았고 할로겐화이온 즉 I^-Cl^-, Br^-에 대한 감응도는 10^-1M∼10^-6M까지 직선관계를 유지하였다. 이 전극을 지시전극으로 이용하여 단일할로겐화이온뿐만 아니라 할로겐화이온의 혼합시료용액의 전위차법적정에 응용할 수 있었다. The ion selective membrane electrode which were prepared with silver halides with PVC-tetrahydrofuran by using the IR pellet press had not only shown the linear potential responses to silver ion in the range of 10^-1 to 10^-6M, but also the slope of responsed potentials had the value of Nernstian slopes. The mechanical and chemical durability of the electrodes were found much better quality than the others. Those electrodes did not be shown any interfering responses except Hg^2+ to cations, and also shown the good responses to halide ions of iodide, chloride and bromide in the range of 10^-1 to 10^-6M. The errors in the titrations of the mixed halide solutions were reduced considerably by adding 0.1M NaNO_3 Soln. and the pulp of filter paper as flocculating agent.

      • 大學卒業定員制의 實施에 따른 學生生活 指導方案에 關한 硏究

        崔根爀,張忠根,李相祐,張鎭吉,張大熙 충남대학교 1982 學生生活硏究 Vol.10 No.1

        Higher education in Korea is faced with a new situation since 1981 when the government implemented a college graduation quota system designed to broaden the opportunities for higher education, alleviate the problem of the students who fail the entrance examination, and improve the quality of college graduates. The change of the system has brought about several serious problems including how to supply enough faculty members, how to provide enough educational facilities, and how to cope with the huge increase in the number of students, 30% more than graduation quota. The greatest single problem resulting from the implementation of college graduation quota system is the psychological and emotional unease aroused among the students, because 30% of those students with unsatisfying results must be banished from college before their graduation. This study aims to find effective measures for student guidance that each of the colleges can implement to help students adjust to the changed circumstances. After objectively investigating the problems from the various educational environments, from the recent students' views of college, and from the psychological and emotional unease arising in them by the fear of failing to graduate from their college because of implementation of the graduation quota system, a survey was conducted by means of a questionnaire composed of 40 questions and by means of personal interviews, 5,903 students, who are influenced by the graduation quota system, attending 19 public and private universities and colleges selected throughout the country. The data obtained from this survey were statistically processed with the help of the C. N. U. Computer Center, and the ratios of the responses to each of the questions were analyzed and calculated according to the distinctions of the total, sex, region, and major. The conclusions that the interrelations among the variant factors from each of the questions which were surveyed, analyzed and arranged have suggested are as follows : 1. The original purpose of graduation quota system should continually be clarified and communicated to all students and a concrete, specialized guidance system should be established to guide the minority of the students (13%) who don't fully understand the basic properties of higher educational institutions. 2. The institutions should provide enough educational facilities and supply enough faculty memebers to solve the problem of accomodating the large numbers of students. At the same time, they should suggest how students should learn positively and effectively to gain an expert knowledge, and how professors should gain public confidence in grade evaluation. Accompanying those measures, the government should develop a good policy to expand and distribute job opportunities to college graduates. 3. The admission quota should be controlled depending on the rate of naturally failed students, and then the students' unease and suppression caused by excessive competition can be relieved. In addition, it is advisable that the banished students should be allowed to transfer to University of the Air without regard to their grades. 4. An education devised to let students have a sound sense and way of thinking should be accompanied by a guidance system which their seniors, parents and society take part in. 5. An atmosphere conducive to sweet and well-rounded friendship among classmates should be created, sound extra-curricular activities should be encouraged and the number of students and adviser professor is in charge of should be lessened to a reasonable number.

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