• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.1-17
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• 1991

The purpose of this study was to analyze the in vivo amalgam corrosion products qualitatively. 30 molars with large, intact amalgam restorations were selected. All the restorations were more than 5 years old. Twenty of the removed amalgams were embedded in acrylic resin block. The exposed surfaces of fifteen embedded amalgams were polished by amalgam polishing kit, and the rest were observed without polishing. The remaining 10 amalgams were fractured centrally and perpendiculary to the occlusal surface with a wire-cutter. After all specimens were cleaned ultrasonically in distilled water, each surface was examined under S.E.M. and E.D.A.X. (Energy Dispersive Micro X-ray Analyzer) to determine the morphology and chemical nature of the corrosion products. The following results were obtained: 1. The surfaces of the unpolished amalgam restorations were covered with thin amorphous layer of Sn-Ca-P-S complex with numerous cracks. 2. In the conventional amalgams, the major corrosion products were Sn-Cl phases however, tin oxide phases were also observed. 3. Only tin oxide phase was identified in the high copper amalgam, but it was less frequently observed than in the conventional amalgam. 4. It was easier to observe the corrosion product morphology in the fractured surfaces than in the polished ones. The morphologies of the corrosion product crystals looked like a stack of slightly bended plates in the Sn-Cl phases and polyhedra or polygonal prisms in the tin oxide phases.

• 약학회지
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• 제41권1호
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• pp.74-80
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• 1997

A polygonal antibody against recombinant hirudin was raised for the development of a ELISA in biological fluids. Recombinant hirudin was conjugated to maleimide activated carrie r protein, KLH and injected to a rabbit. The third booster collection of antiserum was used as primary antibody for the ELISA. The titer for the detection antibody was determined. The direct ELISA could determine the concentration of hirudin in the range of ~10ng/ml. Affinity pulified IgG was obtained and conjugated to horseradish peroxidase. Purified IgG and IgG-HRP could be used as capture and detection antibody, respectively. Although sandwich ELISA would not give the satisfactory results. it could apply for the detection of hirudin level in the range of ~20 ${\mu}$g/ml.

• 한국어병학회지
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• 제32권2호
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• pp.123-127
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• 2019

In this study, white spots appearing in carapace of imported white leg shrimp Litopenaeus vannamei were observed by macroscopic and microscopic examination. White spots due to white spot disease showed two types, white spots with a regular circular shape ranging from 0.4 mm to 1.7 mm and white spots with an irregular shape ranging from 0.05 mm to 2 mm. White spots due to other causes showed four types that appeared as crystalized materials in range of 100 ㎛ around the tegumental gland, as polygonal inorganic deposits ranging from 58 ㎛ to 188 ㎛, as Linear inorganic deposits ranging from 0.8 mm to 9 mm, as brownish spots ranging from 0.1 mm to 0.4 mm, and brownish spots containing melanin ranging from 0.1 mm to 2 mm. As a result, white spots occurred in imported white leg shrimp Litopenaeus vannamei were divide two type, due to white spot disease or other causes, for quarantine works.

• International Journal of Precision Engineering and Manufacturing
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• 제3권4호
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• pp.15-23
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• 2002

With the development of a laser scanner of high precision and increased speed, reverse engineering becomes a key approach to reduce the time for the development of new products. But the modeling process is not so automated enough until now. Modeling in real workshops is usually performed by the experienced operators and it requires a skillful technique to get the resultant surface of high quality and precision. In this paper, a systematic solution is proposed to automate the free-form surface generation from the measured point data. Compatibility is imposed to the measured point data during input curve generation. And the compatibility of cross-sectional curve is also considered for the loft surface generation. The data in each step is produced in IGES file format to make an easy interface to other CAD/CAM software without any further data manipulation.

• 한국정밀공학회지
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• 제18권10호
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• pp.168-177
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• 2001

Reverse engineering has been widely used for the shape reconstruction of an object without CAD data and the measurement of clay or wood models fur the development of new products. To generate a surface from measured points by a laser scanner, typical steps include the scanning of a clay or wood model, the generation of compatible input curves, the generation of a surface and manufacturing data like G code or STL file. A laser scanner has a great potential to get geometrical data of a model for its frost measuring speed and higher precision. The data from a laser scanner are composed of many line stripes of points including small spikes and noise. A new approach using automated surface generating algorithm is introduced to deal with problems during reverse engineering process. And the input data and the generated surface are represented in IGES format, thus can be supplied to other CAD/CAM software without any data manipulation.

• Journal of Welding and Joining
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• 제7권3호
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• pp.44-54
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• 1989

This study was undertaken to evaluate the allowable welding heat input range for high strength steels manufactured by various processes and to compare the weldability of TMCP steel for high heat input welding with that of conventional Ti-added normalized steel. The allowable welding heat input ranges for conventional 50kg/$mm^2$ steel to guarantee D or E grade of ship structural steel were below 150 and 80kJ/cm respectively. Such a limit in welding heat input was closely related with the formation of undesirable microstructures, such as grain boundary ferrite and ferrite side plate in the coarse grain HAZ. In case of 60 and 80kg/$mm^2$ quenched and tempered steels, for securing toughness in weldments over toughness requirements for base metal, each welding heat input had to be restricted below 60 and 40kJ/cm, that was mainly due to coarsened polygonal ferrite in weld metal and lower temperature transformation products in coarse grain HAZ. The TMCP steel could be appropriate as a grade E ship hull steel up to 200kJ/cm, but the Ti-added normalized steel could be applied only below 130kJ/cm under the same rule. This difference was partly owing to whether uniform and fine intragranular ferrite microstructure was well developed in HAZ or not.

• Journal of Welding and Joining
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• 제29권1호
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• pp.65-73
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• 2011

Microstructural characteristics of two high strength (600 MPa & 800 MPa) weld metals produced by flux-cored arc welding process (FCAW) were evaluated. The 600 MPa grade weld metal was consisted of 75% acicular ferrite and 25% ferrite which was formed at relatively high temperature (grain boundary ferrite, widmanstatten ferrite, polygonal ferrite). However, the 800 MPa grade weld metal was composed of about 85% acicular ferrite and 15% low temperature forming phases (bainite, martensite). The prior austenite grain size of 800 MPa grade weld metal was decreased by solute drag force. The compositions and sizes of inclusions which are the dominant factors for the formation of acicular ferrite were analyzed by a transmission electron microscopy (TEM). In both 600 MPa and 800MPa grade weld metals, the inclusions were mainly consisted of Ti-oxide and Mn-oxide, and the average size of inclusions was $0.7{\mu}m$. The 800 MPa grade weld metal exhibited higher tensile strength and similar toughness compared with the 600 MPa grade weld metal. This result is mainly due to a higher fraction of low temperature products and a lower fraction of grain boundary ferrite in the 800 MPa grade weld metal.

• Computers and Concrete
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• 제19권4호
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• pp.413-417
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• 2017

Concrete is a material popularly used in construction. Due to the load-bearing and external environmental factors during utilization or manufacturing, its surface is prone to flaws, such as crack and leak. To repair these superficial defects and ultimately and avoid the deterioration of the concrete's durability, numerous concrete surface protective coatings and crack repair products have been developed. Currently, studies are endeavoring to exploit the mineralization property of microbial strains for repairing concrete cracks be the repairing material for crack rehabilitation. This research aims to use bacteria, specifically B. pasteurii, in crack rehabilitation to enhance the flexural and compression strength of the repaired concrete. Serial tests at various bacterial concentrations and the same $Urea-CaCl_2$ medium concentration of 70% for crack rehabilitation were executed. The results prove that the higher the concentration of the bacterial broth, the greater the amount of calcium carbonate precipitate was induced, while using B. pasteurii broth was for crack rehabilitation. The flexural and compression strengths of the repaired concrete test samples were the greatest at 100% bacterial concentration. Compared to the control group (bacterial concentration of 0%), the flexural strength had increased by 32.58% for 1-mm crack samples and 51.01% for 2-mm crack samples, and the compression strength had increased by 28.58% and 23.85%, respectively. From the SEM and XRD test results, a greater quantity of rectangular and polygonal crystals was also found in samples with high bacterial concentrations. These tests all confirm that using bacteria in crack rehabilitation can increase the flexural and compression strength of the repaired concrete.

• Applied Microscopy
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• 제29권3호
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• pp.383-403
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• 1999

흰쥐 성체 전뇌 기저부의 수직 및 수평 대각 Broca대에서 각 형별 ChAT 면역반응 신경세포의 조직학적 및 미세구조적 특징을 면역조직화학 및 전자현미경을 이용한 면역세포화학적 방법으로 조사하였다. ChAT 면역반응 신경세포에서 광학현미경적 면역반응은 세포체의 세포질과 신경돌기에서 확인되었다. 아울러 미세구조적 관찰로 ChAT 면역반응은 핵외막, 조면소포체의 막, 자유리보좀 그리고 polysomes에서 나타났다. 수직 및 수평 대각 Broca대에서 ChAT 면역반응 신경세포는 세포의 모양과 세포체의 장 단축의 비에 따라 원형, 난형, 세장형, 방추형, 삼각형 그리고 다각형으로 분류되었다. 이 각각의 세포형들을 전자현미경을 이용하여 미세구조적으로 관찰한 결과, 세포체의 크기, 세포질에 대한 핵의 상대적 크기, 세포소기관의 종류 및 분포양상, 신경연접의 수 및 종류 등의 기준에 따라 면역반응 신경세포들은 아유형 I, II로 분류되었다. 그러나, 방추형 및 삼각형 면역반응 신경세포에서는 아유형 I만이 관찰되었다. 아유형 I 면역반응 신경세포는 핵막함입을 보이는 작은 핵과 풍부한 세포질을 포함하였다. 이들 면역반응 세포질은 평행한 긴 수조들로 규칙적인 층판을 이룬 잘 발달된 rER를 함유하였다. 1, 2개의 층판체와 nematosome들이 세포질에서 관찰되었다. 축삭-세포체 신경연접은 주로 대칭형이었으며, 축삭-수상돌기 신경연접은 대다수 비대칭형이었다. 아유형 II 면역반응 신경세포는 비교적 깊은 핵막함입을 보이는 큰 핵과 빈약한 세포질을 포함하였다. rER는 발달이 미약하였다. 축삭-세포체 신경연접은 대칭형과 비대칭형이 같은 비율로 나타났고, 축삭-수상 돌기 신경 연접은 주로 비대칭형이었다. 이상과 같은 미세구조적 관찰에서 ChAT 면역반응 신경세포가 방추형과 삼각형을 제외한 모든 세포형에서 아유형 I, II로 분류되는 것은 투사영역의 원근에 의한 세포 대사활성의 차이에 기인한 것으로 생각된다.