• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 반도체재료
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• pp.57-60
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• 2001

This study describes the effect of $\tau$ -ray irradiation on the properties of insulation materials for low voltage cables in a nuclear power plant. The radiation effects were characterized by measuring OIT, FTIR, electrical properties of the irradiated specimens. As a result, they showed the decrease of OIT and the increase of chemical structural defects with the increase of $\tau$ -ray amount

• Mycobiology
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• 제38권4호
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• pp.321-322
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• 2010

The lichenicolous fungi flora of South Korea is poorly known. During recent field trips to various parts of South Korea and after an extensive examination of herbarium lichen specimens, we encountered a lichenicolous fungi growing over a thallus of the lichen Ochrolechia yasudae Vain., characterized by small black apothecia with mostly three-septate brown ascospores. It was identified as Dactylospora glaucomarioides. This is the first report of this lichenicolous fungus from South Korea. A taxonomic description and comments are presented.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.42-45
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• 2006

This study investigated headed bar anchorage of exterior beam column joints in nuclear power plants. In nuclear power plant structures, anchorage of headed bar is recommended to satisfy ACI 349-01 App. B that are based on the Concrete Capacity Design (CCD) method. However, CCD method may lead to very conservative results for beam column joints where head is anchored within the diagonal strut and concrete is confined by transverse rebar. Compared with results of 5 joint specimens, the anchorage capacities calculated by ACI 349-01 are underestimated by 70-90%. Therefore, it is necessary to amend ACI 349-01 for the mechanical anchorage in beam column joints.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.61-66
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• 2001

Fracture behaviors of pipes with local wall thinning is very important for the integrity of nuclear power plant. In pipes of energy plants, sometimes, the local wall thinning may result from severe drosion-corrosion damage. However, effect of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. From the tests, fracture behaviors and fracture strength of locally thinned pipe were manifested systematically. The observed failure modes were divided into four types; ovalization, ovalization+cracking, local buckling and local buckling+cracking. Also, maximum load was successfully evaluated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.90-95
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• 2003

Fracture behaviors of pipes with local wall thinning are very important for the integrity of nuclear power plant. In pipes of energy plants, sometimes, the local wall thinning may result from severe erosion-corrosion (E/C) damage. However, the effects of local wall thinning on strength and fracture behaviors of piping system were not well studied. In this paper, the monotonic bending tests were performed of full-scale welded and unwelded carbon steel pipes with local wall thinning. A monotonic bending load was applied to straight pipe specimens by four-point loading at ambient temperature without internal pressure. The observed failure modes were divided into four types; ovalization, crack initiation/growth after ovalization, local buckling and crack initiation/growth after local buckling. Also, the strengths of welded and unwelded piping system with local wall thinning were evaluated.

• Asian-Australasian Journal of Animal Sciences
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• 제15권7호
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• pp.1018-1021
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• 2002

The objective of this study was to investigate the villus distribution in the caeca of domestic geese based on the fine structure. The caeca of White Roman geese, 14-week old, were sampled and specimens were detected under photomicroscope and scanning electron microscope (SEM). The results indicated that the villi existed at the proximal caecum. The morphologies of these villi showed finger-like, peak-like or tongue-like shapes. The heights of the villi decreased far from the proximal caecum. No villi were found in the middle and distal caecum. It was obvious that the proximal segment was the main portion for absorbing food nutrients in the caeca. The caecal content particles were small and possessed a viscid character. The large particles filtered out at the proximal caecum just like a mesh. The surface of the middle caecum exhibited parallel ridges with no villi. There were band plicae circular shapes found in the middle caecum under scanning electron microsopy.

• 비파괴검사학회지
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• 제9권2호
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• pp.42-49
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• 1989

It has not been performed to inspect the underclad cracking in Korea nuclear plant since there is no Code Requirements for inspection. However, underclad cracks in nuclear pressure vessels were reported firstly in 1970. The objection of this study is to be established the ultrasonic inspection techniques for underclad cracking. The ultrasonic inspection of bimetalic stainless steel weld is very difficult by high attenuation and multiple scattering at weld surface and weld/base metal interface. The various inspection methods using $70^{\circ}$ refracted longitudinal wave, 50/70 tandem transducer, $45^{\circ}\;and\;60^{\circ}$ single shear wave are compared. Experiments on limited specimens applied same condition to nuclear pressure vessels shows that $70^{\circ}$ refracted longitudinal wave method is the best one for the detection of underclad cracks. 50/70 tandem transducer using SPOT(Satellite Pulse Observation Technique) is more effective for underclad crack sizing than other sizing methods.

• 한국압력기기공학회 논문집
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• 제11권2호
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• pp.40-44
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• 2015

The fatigue behavior of thermal butt fusion in safety class III high-density polyethylene (HDPE) buried piping for nuclear power plants was investigated using load-controlled bending fatigue on four-point bend test specimens. Based on the results, the presence of thermal butt fusion beads was confirmed to reduce the fatigue lifetime in the low- and medium-cycle fatigue regions while having a negligible effect in the high-cycle fatigue regions.

• 동력기계공학회지
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• 제9권4호
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• pp.148-154
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• 2005

Thermostable property is one of most important characteristics of graphite. Commercial graphites sheet from expanded graphite is using for high-temperature elements. Nowadays the new plant with high performance is developed in field of chemical industries, so the need of graphites is increasing rapidly. In this paper, the thermostable properties of newly developed graphite products with high density is investigated. I introduced the graphite material which developed for these heat tests by NGF method in order to test thermostable properties by comparing to the results of the commercial graphite sheet from expanded graphite in same condition. Through measuring the weight reducing ratio with various specimens in some conditions, I investigated the thermostable characteristics of these materials. It is verified that the graphite products by NGF method has almost same or superior thermostable properties comparing with that of commercial graphite sheet. Also the graphite products by NGF method have possibility of being better in thermostable properties.

• Journal of Welding and Joining
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• 제16권4호
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• pp.83-91
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• 1998

Cracking problems which high temperature plant components suffer during long-term service, occur very often at welded locations. The crack occurs due to accumulated creep damage near fusion line or at heat affected zone (HAZ). However, most of the studies on creep crack growth behavior have been performed with matrix metal not wit welded metal due to the difficulty of interpreting the test results. In this study, creep crack growth rates were measured with C(T) specimens whose cracks were formed along the fusion line or HAZ. The measured crack growth rates were characterized by {TEX}$C_{t}${/TEX}-parameter derived for elastic-primary-secondary creeping material. Since contribution of primary creep was significant for the tested 1Cr-0.5Mo steel, its effect was carefully studied. Effects of crack tip plasticity and material aging were also discussed.