• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.1-6
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• 2019

The spermatozoa of Hemiculter eigenmanni is similar to other cyprinid by spherical head containing a nucleus with highly condensed chromatin, a short midpiece with mitochondria and a flagellum located tangentially to the head. The fine structure of cyprinid spermatozoa described classical characteristics of Cyprinidae spermatozoon comprising the absent of acrosome, the shallow nucleal fossa, postnuclear distribution of mitochondria and the lateral insertion of flagellum. However there were some structural differences for their morphology, in the mitochondria and the orientation of centrioles. The proxomal and distal centrioles are oriented approximately $145^{\circ}$ to each other. The mitochondria of 8 or 10 in number are arranged in two or three layers.

• Korean Journal of Materials Research
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• v.9 no.7
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• pp.663-669
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• 1999

Ag thick film conductors were fabricated with Ag powders having different degree of dispersion and glasses having different viscosity, and then the relationship between microstructure and electrical properties of the Ag films was investigated. Under the same processing condition. the Ag thick film that was prepared with the well-dispersed Ag powder and glass having low viscosity had denser microstructure and lower resistance than those of the film which was fabricated with the agglomerated Ag powder and glass having high viscosity It is believed to be due to the fast micro rearrangement kinetics when the well dispersed Ag powder was used, and all the microstructure development kinetics were impeded when low viscosity glass used. It was found that theme fast microstructure development kinetics resulted in the dense microstructure and the lower sheet resistance of the films. Also, the saturation time, at which at a given temperature no further decrease in the sheet resistance was obtained, was found to be shortened when well-dispersed Ag powder and low viscosity glass were used.

• Journal of radiological science and technology
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• v.28 no.3
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• pp.249-254
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• 2005

This study investigated the structural changes of folliculus ovarii according to the dose of the X-rays when mice were exposed to X-rays from 6MeV LINAC. The minute structural changes of folliculus ovarii were observed through an electron microscope with high magnification. Nuclei and protoplasm of granular cells in growing folliculus ovarii abruptly underwent minute structural changes according to the increase of dose of X-rays. Cell residue, by-product of cell decease, neutrophil and macrophage around follicular antrum were observed. The minute structural changes in granular cells showed typical characteristics of apoptosis: the increase of electronic density due to nuclear condensation, fragmentation of nuclei, and atrophy of protoplasm. Necrosis of cells was identified, but it was not so remarkable. Macrophage scattered with apoptotic bodies.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.795-796
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• 2018

방사광은 기존 기계학적인 방법으로 분석했던 연구보다 더 정확한 관찰이 가능해 신뢰도가 높은 결과를 얻을 수 있다. 본 연구의 목적은 흰쥐 정강뼈의 미세구조를 3차원적으로 분석 가능한 방사광기반 경X선을 이용해 골다공증의 진단 및 평가에 필요한 정량화된 분석을 구축하고자 하였다. 흰 쥐의 정강뼈를 방사광을 통해 해부학 구조 및 미세내부구조를 얻은 뒤 3차원적 구조분석을 하였다. 그 후, 방사광으로 얻은 영상 데이터를 통해 뼈 내부 구조를 높은 해상도 이미지로 시각화하여 분석을 할 수 있었다. 따라서, 골다공증과 관련된 퇴행성 골격질환의 정량화된 분석방법을 제시하여 근거중심의 평가와 예방의 기초자료가 될 것으로 기대한다.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.740-748
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• 2001

출발원료 Si 분말의 입자크기를 다양하게 하여 질화반응 및 가스압 소결시 입자크기에 따른 산소함량의 차이에서 나타나는 상변화와 그로 인한 치밀화 거동, 미세구조 발달 및 기계적 특성에 대하여 고찰하였다. 145$0^{\circ}C$의 질화반응에서는 조대분말을 사용한 경우가 미세분말을 사용한 경우보다 높은 질화율을 나타냈으며, 각 분말크기에 따른 native oxide의 함량차에 따라 각기 다른 2차 결정상들이 검출되었다. 조대분말을 사용한 경우에는 제 2상의 석출로 인한 액상량의 부족으로 고온의 소결온도에서도 치밀화를 이루지 못해 낮은 강도값을 나타내었다. 한편, 미세분말을 사용한 경우에는 질화반응 후 석출된 제 2상이 소결온도가 증가함에 따라 용융되면서 치밀화를 이루어 높은 강도값을 나타내었다. 높은 강도값은 미세분말을 사용한 시편들에서 얻어졌으나 높은 파괴인성값은 상대적으로 큰 분말을 사용한 시편들에서 얻어졌는데, 이는 미세한 입자들로 구성된 기지상 내에 잘 발달된 주상정 입자들을 갖는 미세구조에 기인된 것으로 사료된다.

• Journal of the Korean Magnetics Society
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• v.5 no.3
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• pp.197-202
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• 1995

고주파용 전원의 필요성이 대두되면서 고주파에서 낮은 자기손실을 가진 재료의 개발이 요구되고 있다. Mn-Zn 페라이트의 자기손실은 전기비저항의 증거나 소결시 미세구조의 제어로 줄일 수 있다. 본 연구에서는 연쇄고온합성법(Self-propagation High- temperature Synthesis)에 의해 제조된 $_Mn_{0.72}$Z $n_{0.22}$)$_{0.94}$ (F $e_{2}$ $O_{3}$)$_{1.06}$ 조성의 Mn-Zn페라이트에서 첨가물이 미세구조와 자기적 성질에 미치는 영향에 대해 조사하였다. $SiO_{2}$와 Ca $Co_{3}$의 복합첨가에 의해 미세구조의 미세화와 아울러 낮은 자기손실 특성을 얻을 수 있었다. 그러나 첨가 물의 과다 첨가시에는 비정상입자성장 조직이 나타났으며 자기적 성질이 현저히 저하 하였다. 전기비저항, 자기손실의 주파수 의존 결과에 근거하여 주된 자기손실기구 및 이에 미치는 첨가물 효과에 대해 논하였다.

• Korean Journal of Ichthyology
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• v.23 no.2
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• pp.106-110
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• 2011

Fine structure of spermatozoa of the bastard halibut (Paralichthys olivaceus) is described. Its structure is characterized by acrosomeless, having a spherical head region and a small mid piece containing five mitochondria disposed one row. The flagellum inserts centrally on the nucleus and has lateral ribbons. The present study supports the suggestion that spermatozoal ultrastructure is of taxonomic importance and may be a phylogenetic criterion in teleostei.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1977.10a
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• pp.196.3-196
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• 1977

Nocardia sp는 공업폐액의 활성요인로 부터 형태학적으로는 일반세균과 방선균과의 중위위치에 속하는 분류학상 특이한 미생물로서 이의 유녹균으로서는 Corynebacterium, Mycobacterium을 들수있으나 이들과 형태적인 구별은 매우 어렵다. 그러므로 이들 유연균들과 비교하기 위하여 전자현미경에 의한 미세구조를 관찰하였던 바 세포내 unit membrane을 가진 막양구조가 복잡한 형태로 질내에 분포되에 있음을 알았다.(중략)

• Journal of the Korean Ceramic Society
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• v.36 no.1
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• pp.97-105
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• 1999

In the binary system of SiC and carbon, porosity and pore size distribution of green body was controlled by varying pH, by the addition of polyelectrolyte dispersants, and by using different particle size of starting powders. The preforms having different green microstructure were fabricated by slip casting from suspensions having different dispersion condition. The reaction bonding process was carried out for these preforms. The condition of reaction bonding was 1600$^{\circ}C$ and 20 min. under vacuum atmosphere. The analyses of optical and SEM were studied to investigate the effect of green microstructure on that of reaction bonded silicon carbide and subsequently the mechanical properties of sintered body was investigated. Different green microstructures were obtained from suspensions having different dispersion condition. It was found that the pore size could be remarkably reduced for a fine SiC(0.5$\mu\textrm{m}$). The bimodal microstructure was not found in the present study, which is frequently observed in the typical reaction bonded silicon carbide. It is considered that the ratio between SiC and C was responsible for the formation of bimodal microstructure. For the preform fabricated from the well dispersed suspension, the 3-point bending strength of reaction-bonded silicon carbide was 310${\pm}$40 MPa compared to the specimen fabricated from relatively agglomerated particles having lower value 260${\pm}$MPa.

• Korean Journal of Materials Research
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• v.8 no.9
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• pp.871-875
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• 1998

High aspect ratio microstructures were fabricated by photolithography. The material for the microstructure was photosensitive glass which has good mechanical and electrical insulation properties. The photosensitive glass was exposed to ultraviolet light at 312nm through a chromium mask in which the structures are drawn. After heat treatment process over $500^{\circ}C$, the photosensitive glass was etched in a 10% hydrofluoric acid solution with ultrasonic conditions. Final dimension of the micro-framework was greatly dependent on the thickness of photosensitive glass, mask pattern, ultraviolet light exposure and etching conditions. The maximum aspect ratio of the micro-framework obtained from this work was over 30.