• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1996년도 춘계학술대회 논문집
• /
• pp.97-101
• /
• 1996

In this paper, We have studied internal quality incluiding chemical compositions, microscopic structrue and nonmetalic inclusion of test materials. We have analyzed dynamic characteristics of cutting resistence including tensile strength value, hardeness value, impact value etcs. We have compared chip treatments of test materials. In analyzing internal quality, all of test materials have typical ferrite+pearlite structure. But, nonmetallic inclusion have oxide and sulfide inclusion in medium carbon steels, mainly sulfide inclusion is existed in S-free cutting steels. In Ca+S-free cutting steels, calcium aluminate and sulfide complex inclusion, had low-melting points, as deformation of sulfide and oxide inclusion is existed. machining characteristics, cutting resistence is maximum in Ca+S-free cutting steels, minimum in medium carbon steels. Chip treatements are excellent in S-free cutting steels, similar to the Ca+S free cutting steels and medium carbon steels.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 춘계학술대회 논문집
• /
• pp.1626-1630
• /
• 2007

This dissertation finds out trouble types and occurrence regions using the faulty statistics of nondestructive test items in rolling stock parts of the Seoul Metro and using mechanical test about defective and broken parts with broken surface observation, cutting examination about trouble region, hardness experiment and tensile test. Also this dissertation finds out cause of trouble and damage through observation of microscopic formation using metallurgical microscope and scanning electron microscope, residual stress measurement about welding parts and damage diagnosis about defective and broken parts. Moreover it will present the improved plan of nondestructive method about trouble and the removal method of defect and repair welding and find solutions of reliability in parts and preventive maintenance.

• 한국동물위생학회지
• /
• 제13권1호
• /
• pp.64-68
• /
• 1990

This experiment was to investigate the Leptospiral antibody in the pigs with the serological test in two areas of Kangwondo from March to April. 1989. Twelve different living antigen (L. icterohaemorrhagiae, L. pomona, L. hardjo, L. australis, L. canicola, L. autumnalis, L. grippotyphosa, L. tarassovi, L. pyrogenes, L. bataviae, L. lai and L. ballum) of Leptospira interrogans was used for the serological test in the pigs. The blood sample of 280 pigs collected from the slaughter houses were detected by microscopic-agg-lutination test. The results were as follows, 1. Among the serum sample of 280 heads of the pigs, 6 heads of the swine (2.14%) were positive. 2. Among the positive sample of 6 heads, 3 heads of the swine (1.1%) showed the antibody of L. ict-erohaemorrhagiae, 2 heads of the swine (0.7%) showed the antibody of L. canicola, and 1 head of the swine (0.4%) showed the antibody of L. pomona. 3. The positive rate of Leptospira interrogans in the swine of Kangwondo appeared to be very low.

• Journal of Welding and Joining
• /
• 제20권5호
• /
• pp.63-71
• /
• 2002

One of the shortcoming of ferritic stainless steels is their limited toughness. The most important factor governing the toughness of ferritic stainless steels is hewn to be their interstitial contents. Due to the limited solubility of carbon and nitrogen in the ferrite matrix, it is difficult to avoid carbide and nitride precipitates. In the study, the role of nitrogen on the toughness of 260r-2Mo superferritic stainless steel welds has been investigated using alloys containing various nitrogen levels between 100 and 1640 ppm. Mechanical properties of weld metals have been evaluated by microhardness, Charpy impact test and notch tensile test. The alloys are mainly embrittled by the grain boundary and intragranular nitride precipitation. Grain boundary precipitates are considered to be more deleterious than intrauanular nitrides. Fracture mechanism have been elucidated through microscopic evaluation of notch tensile test

• 한국동물위생학회지
• /
• 제15권1호
• /
• pp.46-50
• /
• 1992

This experiment was to investigate the Leptospiral antibody in the pigs with the serological test by the microscopic-agglutination-test (MAT) from November 1991. to Januaury 1992. Antigen(living antigen) was used L. icterohemorrhagiae, L. pomona, L. canicola, L. hardjo, L. ballum, L. australis, L. autumnalis, L. grippotyphosa, L. tarassovi, L. pyrogenes, L. bataviae, L. hebdomadis for the serolgical test in the pigs. The result obtained are summarized as follows of the total 202 serum samples examined, 1. Among the serum samples of 202 heads, 19 heads of the pigs(9.4%) were positive. 2. Among the positive samples of 19 heads, The detected were L. icterohemorhagiae 10 heads(5.0%), L. pomona 3 heads(1.5%), L. canicola 6 heads(3.0%). 3. Antibody titers of positive sera were ranging from 1：100 to 1 : 400. Serotiters appeared to be very low, 4. The seroprevalence of Leptospira in Chechon was higher than that other districts (5. 4% -5.8%), but the lower than Chung-nam, Kyonggi(13.7-15.9%)

• 한국정밀공학회지
• /
• 제14권7호
• /
• pp.22-28
• /
• 1997

In this paper, We have studied internal quality incluiding chemical compositions, microscopic structure and nonmetalic inclusion of test material. We have analyzed dynamic characteristics of cutting resistence and compared chip treatment of the test material. In analyzing internal quality, all of the test material have typical ferrite+pearlite structure. But, nonmetallic inclusion has oxide and sulfide inclusion has oxide and sulfide inclusion in medium carbon steel, mainly sulfide inclusion is existed in S-free cutting steel. In Ca+S-free cutting steel, calcium aluminate and sulfide complex inclusion, had low-melting point, as deformation of sulfide and oxide inclusion is existed. Machining characteristics, cutting resistence is maximum in medium carbon steel. Chip treatement are excellent in S-free cutting steel, similar to the Ca+S free cutting steel and medium carbon steel.

• 한국기계가공학회지
• /
• 제7권3호
• /
• pp.110-114
• /
• 2008

In this study, to examine the friction coefficient and wear amount of dental prosthesis, pin-on-disk type wear test were at room temperature. Vickers hardness and fracture toughness measurement of dental materials were preformed. Microscopic observations on worn surfaces of specimens were conducted by SEM. The friction coefficient of dental material was investigated according to weight and slinging velocity. dental material have investigated composed to nature teeth.

• 대한수의학회지
• /
• 제21권2호
• /
• pp.113-116
• /
• 1981

This experiment was undertaken to determine the causative agent of dermatophytosis occured in the 3 common seals and a elephant which were derived from the Tae-gu and Busan zoological gardens. Direct microscopic examination, culture and pathogenicity test were performed for the samples obtained from the skin lesions of the affected common seals and elephant. The causative agent was identified as Trichophyton mentagrophytes exclusively in these cases, and the present report describes the first cases of the common beat and elephant ringworm.

• 한국강구조학회 논문집
• /
• 제29권1호
• /
• pp.37-48
• /
• 2017

본 연구에서는 HSA800 60mm 강재의 SAW 용접성 및 이음성능을 확인하기 위해 후열처리 1시간과 2시간에 대한 SAW 공시체를 제작하여 9종의 시험을 실시하였다. 용접부 충격시험, 굽힘시험, 경도시험, 매크로조직시험, 마이크로조직시험 결과 SAW PH1 및 PH2는 양호한 용접부로 나타났으나, 화학성분시험 결과 P성분이 KS를 만족하지 못하였다. 용접부 평판 및 봉형 인장시험결과 SAW PH1에 비하여 PH2의 기계적 특성이 양호하게 나타났기 때문에 SAW의 경우 후열처리는 2시간을 권장한다.

• 한국식물병리학회:학술대회논문집
• /
• 한국식물병리학회 2003년도 정기총회 및 추계학술발표회
• /
• pp.139.2-140
• /
• 2003

Ornithogalum showing mosaic symptoms were collected from the isolated field of National Plant Quarantine Service in Sengrimmyon of Kyungnam province. Electron microscopic examination of negatively strained preparation was filamentous particle of 740nm in lenght. Indirect-ELISA determined that the virus was serologically related to potyvirus. A single major protein band of Mr 30,000 was observed after sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Indicator plant test showed masaic, necrotic local lesion and sunken areas in leaves of Nicotiana clevelandii and Tetragonia expansa, while the others of indicator plants did not infect. An enzyme-aided purification protocal was used, which eliminated a highly viscous mucilage from extracts of the Omithogalum. Total RNA extracted from infected Omithogalum leaves were amplified of 411b.p fragment in reverse transcription (RT)-PCR when primers specilic for the coat protein gene. An isolate of Omithogalum mosaic virus (OrMV) of the genus Potyvirus was identified as the casual agent of the disease on the basis of electron microscopic, biological and serological reaction.