• 터널과지하공간
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• 제19권4호
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• pp.366-372
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• 2009

최근, 암반발파에서 평활한 파단면과 굴착손상영역을 제어하기 위한 목적으로 전자지발뇌관 및 노치장약공 등을 이용한 제어발파기술들이 개발되어 오고 있다. 본 연구에서는 날개형 노치 장약공을 이용한 SB발파에서 암반 내 파괴과정을 모사하여 파단면과 암반손상제어에 미치는 영향인자에 대하여 고찰하였다. 최종적으로 장약공 노치의 파단면 제어효과에 관한 수치해석적 고찰을 날개형 노치장약공과 전자뇌관을 이용한 새로운 SB발파법으로, ED-Notch SB발파법(Elerectronic Detonator Notched Charge Hole Smooth Blasting Method)을 제안하였다.

• 한국해양공학회지
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• 제1권1호
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• pp.127-137
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• 1987

The evaluation of the elastic-plastic fracture toughness $J_{1C}$ was performed on the center of weld metal(CWM), the heat affected zone (HAZ) and the base metal (BM) of API 5LB steel pipes welded by the high frequency electric resistance welding. The $J_{1C}$ was evaluated by the JSME R-Curve and JSME SZW methods using the smooth and side-grooved specimens. The results are as follows; (1) The $J_{1C}$ values by the SZW method are overestimated as compared with those by the R-curve method, because the micro-crack is formed as SZW increase with the deformation at SZ after initiation of the ductile crack. (2) The everage of $J_{1C}$ values by the the R-curve and the SZW methods in side-grooved specimens tended to decrease in comparison with smooth specimens 9.42% at CWM, 4.2% at HAZ, 23.2% at BM, respectively. (3) The boundary of the fatigue pre-crack, stretched zone, and dimple regions appeared more clearly in side-grooved specimens, for the slight change of SZW in the direction of the plate thickness, as compared with smooth specimens.

• 대한수의학회지
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• 제34권3호
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• pp.435-439
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• 1994

The present observation was focussed mainly on the histopathological and immunohistochemical finding of the tumor developing from the outside of rat uterus wall. In gross finding, this tumor were a oval form mass and 0.75cm and 1cm in greatest demension. The sectioned surface showed uniform, solid, gray-white. In histopathological finding, the tumor showed the form of lymphoid nodule-like structure and was composed of the cells with karryorrhexis, karyolysis and necrosis in the central zone, mature cells in the paracentral zone, and concentric layers of compressed, flattened and atrophied smooth muscle fibers by the proliferating of the cells closely resembling endometrial stromal ells in the peripheral zone and a few smaller nodule-like structure in certain areas of the peripheral zone. In immunohistochemical observations, the proliferating cells presents only among the concentric layers of the smooth muscle fibers in the peripheral zone. Labeling index of proliferating cells in the peripheral zone was $4.34{\pm}1.28%$. These tumor cells did not metastasized in another orgns and labeling index was low, So it was concluded that this tumor was benign stomal sarcoma.

• 터널과지하공간
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• 제21권3호
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• pp.235-243
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• 2011

본 연구에서는 SB발파에서 평활한 최종파단면과 발파손상영역을 제어하고, 동시에 발파진동을 제어하기 위한 목적으로 무장약 균열 유도공을 이용한 제어발파기법을 제안하였다. 무장약 균열유도공의 파단면 제어 유효성을 검토하기 위하여 일반 SB발파와 무장약 균열 유도공 적용한 SB발파에서 암반 내 발생하는 파괴과정을 수치해석법으로 모사하여 파단면을 분석하였다. 제발효과를 높이기 위하여 도폭선에 의한 기폭을 고려하였으며, 무장약 균열 유도공을 중심으로 양쪽에 장약공이 설치된 일자유면 발파로 가정하여 암반의 파괴과정해석을 수행하여 SB발파에서 무장약 균열 유도공에 의한 파단면 형성 기구를 고찰하였다. 결과적으로, 공간격이 40cm 이하에서 무장약 균열 유도공을 사용한 경우가 낮은 파단면 거칠기를 보여 파단면 제어 효과가 있음을 입증 하였다.

• 대한조선학회논문집
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• 제43권4호
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• pp.494-503
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• 2006

Inherent damage zone model is presented to explain the fatigue properties near the fatigue limit and the crack growth threshold consistently Inherent damage zone model assumes that the stress at a point which is located at a small distance, $r_0$, an inherent length of the material that represents the size of effective damage zone, from the crack initiation position governs the fatigue characteristics regardless of the geometric configuration of the specimen; smooth specimen, notched specimen or cracked specimens with short and long crack length. A special feature of the paper is using the exact stress distributions of notched and cracked specimens at the strength evaluations. Analytical elastic solutions by Neuber and Westergaard are employed for this purpose Relationship between fatigue limit of smooth specimen and threshold stress of cracked specimen, occurrence condition of non-propagating crack at the root of elliptic notch and circular hole and relationship between stress concentration factor and fatigue notch factor are discussed quantitatively based on the proposed model.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.88-95
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• 2005

The head to disk spacing must be decreased to increase recording densities in hard disk drives. Recently, to decrease the head to disk spacing, smooth disk having no bumps onto the lading zone has used. In this research, we compared the number of particles generated in HDD with smooth and textured disks. We used a sampling method using a particle sampler and a CPC (condensation particle counter) to detect particles in HDD. First, we sampled and counted panicles generated with disk rotational speed and various rest times when the smooth disk and textured disks were used, then analyzed the sampled particles by SEM (scanning electron microscopy) and AES (auger electron spectroscopy). In results of measuring particles, more particles in case of LZT disk drive generated than that of the smooth disk drive in all test modes. The number of particles generated in the smooth disk was very low. The particle generation increased as the rest time increased (smooth/LZT disks) and more particles in case of LZT disk drive generated than that of the smooth disk drive. In results of analyzing particle components, Al, Ti, Si components were detected and we could not found differences between components in case of smooth/LZT disk drive.

• 정보저장시스템학회논문집
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• 제2권2호
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• pp.123-129
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• 2006

The head to disk spacing must be decreased to increase recording densities in hard disk drives. Recently, to decrease the head to disk spacing, smooth disk having no bumps onto the lading zone has used. In this research, we compared the number of particles generated ill HDD with smooth and textured disks. We used a sampling method using a particle sampler and a CPC (condensation particle counter) to detect particles in HDD. First, we sampled and counted particles generated with disk rotational speed and various rest times when the smooth disk and textured disks were used, then analyzed the sampled particles by SEM (scanning electron microscopy) and AES (auger electron spectroscopy). In results of measuring particles, more particles in case of LZT disk drive generated than that of the smooth disk drive in all test modes. The number of particles generated in the smooth disk was very low. The particle generation increased as the rest time increased (smooth/LZT disks) and more particles in case of LZT disk drive generated than that of the smooth disk drive. In results of analyzing particle components, Al, Ti, Si components were detected and we could not found differences between components in case of smooth/LZT disk drive.

• 접착 및 계면
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• 제5권2호
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• pp.31-42
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• 2004

Many animals possess on their legs adhesive pads, which have undergone evolutionary optimization to be able to attach to variable substrates and to control adhesive forces during locomotion. Insect adhesive pads are either relatively smooth or densely covered with specialized adhesive hairs. Theoretical models predict that adhesion can be increased by splitting the contact zone into many microscopic, elastic subunits, which provides a functional explanation for the widespread 'hairy' design. In many hairy and all smooth attachment systems, the adhesive contact is mediated by a thin film of liquid secretion between the cuticle and the substrate. By using interference reflection microscopy (IRM), the thickness and viscosity of the secretion film was estimated in Weaver ants (Oecophylla smaragdina). 'Footprint' droplets deposited on glass are hydrophobic and form low contact angles. IRM of insect pads in contact showed that the adhesive liquid is an emulsion consisting of hydrophilic, volatile droplets dispersed in a persistent, hydrophobic phase. I tested predictions derived from film thickness and viscosity by measuring friction forces of Weaver ants on a smooth substrate. The measured friction forces were much greater than expected assuming a homogenous film between the pad and the surface. The findings indicate that the rubbery pad cuticle directly interacts with the substrate. To achieve intimate contact between the cuticle and the surface, secretion must drain away, which may be facilitated by microfolds on the surface of smooth insect pads. I propose a combined wet adhesion/rubber friction model of insect surface attachment that explains both the presence of a significant static friction component and the velocity-dependence of sliding friction.

• 대한기계학회논문집
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• 제19권4호
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• pp.918-928
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• 1995

This paper deals with the various mechanical properties and fatigue strength in the FRW1 (friction welded interface) of high speed steel (HSS-Co) to SM55C through the tensile test, hardness test and fatigue test. The data of FRW specimens are also compared with those of the base materials (HSS-Co and SM55C steel). Three kinds of specimens used in this study are the friction welded joints, HSS-Co and SM55C carbon steel with circumferential notch, saw notch and smooth, respectively. It is confirmed that the applied welding conditions are optimum methods in order to minimize the heat affected zone (HAZ) and hardness distribution at the HAZ. The fatigue strengths at N = 10$^{6}$ cycles of smooth, circumferential notch and saw notch specimens in the FRW joints are about 299.2 MPa, 123.8 MPa and 247.5 MPA, respectively. The fatigue strength of the friction welded joints is almost equal to that of the SM55C carbon steel in the optimum welding conditions. The fatigue cracks initiated at the welded zone are propagated along the side of SM55C steel.

• Spatial Information Research
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• 제10권3호
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• pp.439-453
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• 2002

수자원분야에서 DEM을 활용한 연구들이 활발히 진행되고 있으며, 특히 지형 및 수문분석의 기초가 되는 유역과 하천 추출은 GIS 분석에서 일반화되어 있다. 그러나 경사가 완만한 지형에서는 가늘고 긴 슬리버 폴리곤 형태의 유역이나 직선형태의 하천이 추출되므로, 활용측면에서 비 효율적이다 본 연구에서는 완경사지역에서 발생하는 비정상적인 유역과 하천을 효과적으로 추출하기 위해, 하천을 중심으로 완충구간을 설정한 후 점진적인 표고변화를 적용하였다. 특히 점진적인 표고변화를 부여하기 위해 보로노이 다이어그램(Voronoi Diagram)을 활용한 등거리 할당모형을 적용하였다. 또한 추출한 하천인식 DEM과 원시 DEM을 이용하여 유역 및 하천을 추출한 후, 완경사 지역에서의 유역 및 하천의 형태를 상호 비교함으로서 본 연구의 효용성을 평가하였다.