• 한국어병학회지
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• 제11권1호
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• pp.69-76
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• 1998

매년 폐사가 발생해 온 서해안 연안의 고창과 태안에서 채집한 양식 바지락에서 복합포자충류인 Perkinsus sp.가 관찰되었다. 기생충에 감염된 바지락은 육안적으로 아가미와 육질의 표면에서 유백색의 결절이 나타났다. 기생충의 영양체는 편재된 핵을 가지고 있으며, 아가미와 외투막, 간 췌장, 생식소 조직에서 이분열에 의해 증식하며, 육아종의 형성과 혈구의 침윤을 유발하였다. 감염된 바지락을 FTM에 배양한 결과 영양체의 크기가 커지면서 루골용액에 의해 검게 염색된 구형의 유주자낭들 형성하였다. Perkinsus sp.의 평균 감염율은 9개월의 조사 기간 동안 고창이 73.1%, 태안이 94.8%로 나타났으며, 감염율은 각장의 크기가 클수록 증가하는 경향을 나타내었다. Hemacolor kit는 바지락의 대량폐사와 밀접한 연관이 있는 Perkinsus sp.의 영양체의 신속진단에 유용한 것으로 나타났다.

• 한국어류학회지
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• 제30권2호
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• pp.114-118
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• 2018

매가오리목, 색가오리과에 속하는 Pteroplatytrygon violacea 1개체(전장 1,058 mm)가 2017년 7월 6일 제주도 북서쪽 연안에서 처음으로 유자망에 의해 채집되었다. 이 종은 넓은 주둥이를 갖는 점, 5쌍의 아가미구멍이 있는 점, 꼬리에 1개의 가시가 있는 점, 꼬리의 배쪽에 있는 피습이 꼬리끝까지 이르지 않는 점, 꼬리의 등쪽에는 피습이 없는 점, 그리고 배의 표면은 전체적으로 어두운 자주색을 띠는 것이 특징이다. 이러한 형태적 특징에 따라서 이 종을 P. violacea로 동정하였으며, 표본의 COI 유전자 염기서열을 이용하여 종동정을 확인하였다. 이 미기록종은 배 표면의 체색으로 인해 기존에 붙여진 이름에 따라 종명과 속명을 각각 "보라색가오리"와 "보라색가오리속"으로 제안한다.

• 한국어병학회지
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• 제17권1호
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• pp.21-28
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• 2004

양식 미꾸라지 (Misgurnus mizolepis)가 수중으로 잠입하지 못하고 양어지의 물표면에 배를 위로 한 채 힘없이 회전 유영을 하는 질병이 발생하였다. 병어는 복부가 팽만되어 있었으며, 해부하여 보면 소화관에 커다란 공기방울의 축적, 장염이 현저하였다. 병어를 혈액학적으로 조사한 결과 적혈구수, Ht치 및 Hb 농도는 건강어와 차이가 없었다. 병리조직학적으로는 아가미의 호흡상피의 증생과 새변의 유착, 소화관 상피세포의 출혈, 괴사 및 박리가 관찰되었다. 뒷지느러미와 항문사이를 실로 결박하여 항문으로부터 공기의 배출을 억제한 재현 실험에서 발병어와 같은 증상이 재현되었다. 따라서 이 병은 빠른 성장을 목적으로 고단백질 사료를 투여함으로서 장호흡을 위하여 마신 공기가 소화관내에 축적되고, 축적된 공기의 부력 때문에 물속으로 하강하지 못하게 되고, 또 소화관을 압박하여 소화관에 순환장애를 일으킨 결과 폐사한 것으로 추정된다.

• 열처리공학회지
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• 제5권4호
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• pp.195-200
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• 1992

SCM 415 has been vacuum carburized in the carburizing pressure of 60-65kpa and the carburizing temperature of 1233k and 1273k after varied to 0-20 in the ratio of $N_2/C_3H_8$ and then diffusion treated for various times at 1123k. The results obtained from the experiment are as follows. 1. With increasing from 0 to 20 in ratio of $N_2/C_3H_8$ the sooting formation of surface after carburizing considerably decreased. 2. The hardness control and surface carbon content of carburizing surface has been modified by the addition of nitrogen to the propan. 3. The appoximate value of k is indirectry calculated at 1123k which results are obtained to $0.58{\times}10^{-2}(wt.%.S^{-1/2})$. 4. A great deal of propan by addition of nitrogen gas in carburizing gas was possible to saving without considerable change in case hardening depth. 5. The effective carburizing depth range is obtained to 0.8-1.1mm by diffusion temperature of 1123k after carburization at 1273k-3.6ks, and the surface hardness is increased as the increasing of $T_D/T_c$ in our experimental condition, and the maximum hardness as reachin distance from surface is decreased.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.16-27
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• 2008

The interaction between advancing ships and the waves generated by them plays important roles in wave resistances and ship motions. Wave breaking phenomena near the ship bow at different speeds are investigated both numerically and experimentally. Numerical simulations of free surface profiles near the fore bodies of ships are performed and visualized to grasp the general trend or the mechanism of wave breaking phenomena from moderate waves rather than concentrating on local chaotic irregularities as ship speeds increase. Navier-Stokes equations are differentiated based on the finite difference method. The Marker and Cell (MAC) Method and Marker-Density Method are employed, and they are compared for the description of free surface conditions associated with the governing equations. Extra effort has been directed toward the realization of extremely complex free surface conditions at wave breaking. For this purpose, the air-water interface is treated with marker density, which is used for two layer flows of fluids with different properties. Adaptation schemes and refinement of the numerical grid system are also used at local complex flows to improve the accuracy of the solutions. In addition to numerical simulations, various model tests are performed in a ship model towing tank. The results are compared with numerical calculations for verification and for realizing better, more efficient research performance. It is expected that the present research results regarding wave breaking and the geometry of the fore body of ship will facilitate better hull form design productivity at the preliminary ship design stage, especially in the case of small and fast ship design. Also, the obtained knowledge on the impact due to the interaction of breaking waves and an advancing hull surface is expected to be applicable to investigation of the ship bow slamming problem as a specific application.

• 공업화학
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• 제34권1호
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• pp.9-14
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• 2023

본 논문에서는 용액의 이온 농도 측정이 가능한 나피온 폴리머(Nafion polymer) 코팅 기반 2상 금 전극의 임피던스(Impedance) 센서를 개발하였다. 스퍼터링(Sputtering) 공정을 통해서 제작된 금 전극의 표면을 나피온 폴리머를 사용하여 표면 개질 하였다. 상기 제작된 전극은 분극 현상 제어가 가능하여 전기화학적 신호를 안정적으로 측정할 수 있도록 하였다. 분광학과 전자주사현미경 관찰을 통하여 박막의 나피온 폴리머 코팅을 확인하였다. 나피온 코팅이 된 전극은 기존 금 전극에 비해 안정적인 임피던스 신호를 보여 주었으며, 표준 염화나트륨(NaCl) 용액 사용 시 임피던스 센서의 신뢰성 높은 검정 곡선(R² = 0.983)을 나타내었다. 또한, 임피던스 센서는 상용화 전도도 장치와 인공 눈물의 이온 농도 측정 비교 실험을 진행하였으며, 유사한 결과값을 확인하였다.

• The Korean Journal of Ecology
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• 제20권1호
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• pp.51-59
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• 1997

To investigate the distribution of heavy metal concentrations in Onsan bay, concentrations of cadmium, copper, zine and lead in surface sediments and the periwinkles (Littorina brevicula) were determined in Feburary and July, 1996. The ranges of cadmium, copper, zinc and lead concentrations in the surface sediments were 0.08-3.72, 3-307, 49-1273 and 15-399 ${\mu}g/g$ dry weight, respectively, The decrease of concentration in heavy metals with distance from Daejeong stream indicated that this stream is the pollutant source of heavy metals in Onsan Bay. The concentrations of cadmium, copper, zinc and led in L. brevicula were 0.11-11.81, 21-212, 30-96 and 0.26-4.12 ${\mu}g/g$ dry weigth in February and 1.01-24.9, 66-325, 54-225 and 0.68-8.41 ${\mu}g/g$ dry weight in July, respectively. These concentrations in L. brevicula were the significantly different (p<0.001) with the season of sampling. However, overall distribution of concentrations of heavy metals in L. brevicula had very similar tendency that concentrations of heavy metal decreased with the distance from the pollutant source irrespective of the two seasons. Therefore, L. brevicula is considered as a useful indicator for heavy metals pollution, According to analysis of the organs, tissues such as the digestive gland, gill and viceral mussel accumulate high concentrations of heavy metals.

• 한국어병학회지
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• 제1권2호
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• pp.95-101
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• 1988

During the period from August through October, 1988, 50 isolates of Edwardsiella tarda were isolated from 6 diseased cultured Channa argus in Dunchi island and Myung-ghi, near Pusan in Korea were examined by studying their biochemical and antibiotical reactions. The ill animals moved slowly and irregular-formed swimming at the surface of the corner. The symthoms were necrosis with hemorrhage on the body surface, head, gill region, and mouth. Some fish were observed dropsy of the belly. The bacteria grew slowly on Double Salmonella-Shigella agar, 24h, at $37^{\circ}C$ to form relatively small size (2mm diameter), smoothed and convexed form with transient or black in center of the colonis. They gave negative reactions to Voges-Proskauer, Simmon's citrate, urea, KCN (in growth), gelatin, arginine dehydrolase, phenylalanine deaminase and many sugars. The isolates showed positive reactions to $H_2S$ (in KIA agar), indol, Methyl-Red, motility, lysine and ornithine decarboxylase, and gas from glucose. 8 drugs tested as chloramphenicol, colistin, gentamicin, kanamycin, lincomycin, nalidixic acid spectinomycin, and tetracycline. All cultures were resistant to colistin, lincomycin and spectinomycin respectibly, but sensitive to kanamycin and nalidixic acid. Three strains showed resistance to chloramphenicol and 2 isolates among them were resistant to two drugs(gentamicin and tetracycline), coincidentally.

• Bulletin of the Korean Chemical Society
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• 제31권12호
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• pp.3723-3729
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• 2010

We investigated the high-excitation voltage cathodoluminescence (CL) performance of blue light-emitting (ZnS:Ag,Al,Cl) and green light-emitting (ZnS:Cu,Al) phosphors coated with metal oxides ($SiO_2$, $Al_2O_3$, and MgO). Hydrolysis of the metal oxide precursors tetraethoxysilane, aluminum isopropoxide, and magnesium nitrate, with subsequent heat annealing at $400^{\circ}C$, produced $SiO_2$ nanoparticles, an $Al_2O_3$ thin film, and MgO scale-type film, respectively, on the surface of the phosphors. Effects of the phosphor surface coatings on CL intensities and aging behavior of the phosphors were assessed using an accelerating voltage of 12 kV. The MgO thick film coverage exhibited less reduction in initial CL intensity and was most effective in improving aging degradation. Phosphors treated with a low concentration of magnesium nitrate maintained their initial CL intensities without aging degradation for 2000 s. In contrast, the $SiO_2$ and the $Al_2O_3$ coverages were ineffective in improving aging degradation.

• 대한조선학회논문집
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• 제48권6호
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• pp.560-568
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• 2011

In SPH(Smoothed Particle Hydrodynamics) method, the fluid has been assumed that it is weakly compressible to solve the basic equations composed of Navier-Stokes equations and continuity equation. That leads to some drawbacks such as non-physical pressure fluctuations and a restriction as like small time steps in computation. In this study, to improve these problems we assume that the fluid is incompressible and the velocity-pressure coupling problem is solved by a projection method(that is, by ISPH method). The two-dimensional computation results of dam breaking and gravitational wave generation are respectively compared with the results of finite volume method and analytical method to confirm the accuracy of the present numerical computation technique. And, the agreements are comparatively acceptable. Subsequently, the green water simulations of a two-dimensional fixed barge are carried out to inspect the possibility of practical application to ship hydrodynamics, those correspond to one of the violent free surface motions with impact loads. The agreement between the experimental data and the present computational results is also comparatively good.