• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.1001-1005
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• 2005

현재 평화의 댐 배수터널은 직경 10m 원형 x 4 련의 콘크리트 라이닝 터널로 구성되어 있다. 배수터널내의 흐름특성은 터널직경, 모양, 터널결사, 조도계수 및 입구부와 출구부의 기하학적 성질, 터널의 상류수위와 하류수위 등에 따라 개수로 혹은 관수로의 흐름특성이 나타난다. 따라서 터널내의 흐름은 각각의 경우에 따른 수리학적 해석이 달리 적용되어진다. 화천댐의 수위와 연계하여 평화의 댐 방류량을 산정하기 위해서는 상$\cdot$하류 수위에 따른 관로내의 흐름특성이 다양하게 변화하는 바 이에 따른 수리학적 검토가 필요하게 된다. 본 연구에서는 배수터널의 흐름별로 계산 방법을 도출하였으며 상$\cdot$하류의 수위와 단면형태를 고려하여 먼저 배수터널내의 흐름특성을 규명한 다음 그에 합당한 유량산정공식으로 배수터널 내에서 유하하는 흐름의 유량값을 산정할 수 있는 방법을 제시하였다. 본 검토에서 구축된 계산절차에 의해서 평화의 댐 수위가 급격하게 변화하는 시점인 2002년 1월, 6월 그리고 2004년 8월 시점의 평화의 댐, 화천댐의 수위를 검토하여 방류량을 산정하였다. 평화의 댐에서는 방류량을 결정하기 위한 계측시설이 없기 때문에 가장 가까운 하류부의 화천댐 유입량과 비교를 수행하게 된다. 강우가 지속되면서 화천댐의 유입량이 증가를 하게 되는데 화천댐 유역의 국지적인 호우에 따른 유입량으로 판단되는 부분을 제외하고는 화천댐 유입량과 계산된 평화의 댐 방류량에서 유사한 결과를 도출하고 있었다. 이와 같은 산정법을 바탕으로 하여 강우에 따른 평화의 댐 방류량을 정확히 산정함으로서 댐유역의 비상사태 발생 또는 임남댐의 방류 등을 추정하는데 크게 기여할 수 있을것으로 판단된다.2$으로 나타났다. 밸브 개폐도가 $100\%$일 때가 밸브를 $60\%$와 $80\%$ 개폐시켰을 때보다 $0.3kg/cm^2,\;0.29kg/cm^2$ 낮게 나타나 밸브를 전체 개방 했을 때 관로내의 수압이 상수설계기준에 적합한 수압을 유지함을 알 수 있다. 상수관로 설계 기준에서는 관로내 수압을 $1.5\~4.0kg/cm^2$으로 나타내고 있는데 $6kg/cm^2$보다 과수압을 나타내는 경우가 $100\%$로 밸브를 개방하였을 때보다 $60\%,\;80\%$ 개방하였을 때가 더 빈번히 발생하고 있으므로 대상지역의 밸브 개폐는 $100\%$ 개방하는 것이 선계기준에 적합한 것으로 나타났다. 밸브 개폐에 따른 수압 변화를 모의한 결과 밸브 개폐도를 적절히 유지하여 필요수량의 확보 및 누수방지대책에 활용할 수 있을 것으로 판단된다.8R(mm)(r^2=0.84)$로 지수적으로 증가하는 경향을 나타내었다. 유거수량은 토성별로 양토를 1.0으로 기준할 때 사양토가 0.86으로 가장 작았고, 식양토 1.09, 식토 1.15로 평가되어 침투수에 비해 토성별 차이가 크게 나타났다. 이는 토성이 세립질일 수록 유거수의 저항이 작기 때문으로 생각된다. 경사에 따라서는 경사도가 증가할수록 증가하였으며 $10\% 경사일 때를 기준으로 $Ro(mm)=Ro_{10}{\times}0.797{\times}e^{-0.021s(\%)}$로 나타났다.천성 승모판 폐쇄 부전등을 초래하는 심각한 선천성 심질환이다. 그러

• Journal of the Mineralogical Society of Korea
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• 제15권3호
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• pp.221-230
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• 2002

Weathering of biotite shows a biotite-vermiculite-kaolinite sequence at the early stage, but presents biotite-kaolinite sequence without a significant intermediate phase (vermiculite) at the late stage from the weathering profile of the granitic gneiss. Secondary 1:1 phyllosilicates are kaolinite and halloysite which show different weathering textures originated by a different formation mechanism. Kaolinitization began from the edges of biotite and propagated toward the interior of grain along a multilayered front. $10 \AA$ layers of biotite are interleaving with $7\AA$ layers of kaolinite and c-axis of two phases is consistent. Kaolinite pseudomorph of biotite is isovolumetric, compared to the biotite boundary and includes many band-like porosities parallel to the cleavage. Platy kaolinite formed by 1:1 layer fur layer replacement of biotite. Halloysitization proceeded outward from the grain edges which were foliated as fine flakes and bent at the right angle for cleavage Halloysites were extensively fanning out and greatly increased the volume of grain. This indicated that halloysite tubes were formed by epitaxial overgrowth on the surface of biotite with import of Si and Al from the external solution by dissolution of plagioclase. These halloysites have abnormally high Fe content ( ~11%).

• The Journal of Korean Society for Radiation Therapy
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• 제19권2호
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• pp.131-141
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• 2007

Purpose: Try to compare dose distribution and lung dose of radiation treatment plan of the breast cancer that used Irregular Surface Compensator (ISC) and treatment plan that used a wedge filter. Materials and Methods: Established a treatment plan to be distributed over 95% of prescription dose (5,040 cGy) of the two tangent-half fields that used a wedge filter and ISC at a breast organization as made to breast cancer patient having an irregular surfaces after surgery. Compared high dose area and DVH, and verified a treatment plan as used film with rectangular phantom. Results: Maximum dose point in breast tissue appeared to 107.5% in case of tangent-half fields Tx plan that used a wedge filter, and lung volumes exposed above 20 Gy by 7.63%. In case of ISC, maximum dose point in breast tissue appeared to 106.4%, and lung volumes exposed above 20 Gy by 6.5%. The film measurement results that used phantom, 105$\sim$110% high dose region was distributed to the upper part and both edges of phantom. However in case of ISC, appeared by 100$\sim$105% dose conformity distribution. Conclusion: In general, the Irregular Surface Compensator (ISC) can improve the dose conformity of breast tissues, as well as reduced hot spots in the lung and in the breast. Such an advantage by using ISC technique is more beneficial for patients who have more irregular surfaces after surgery.

• Tunnel and Underground Space
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• 제22권1호
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• pp.69-76
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• 2012

Theoretical backgrounds on the experimental methods of explosive welding, explosive forming and shock consolidation of powders are introduced. Explosive welding experiments of titanium (Ti) and stainless steel (SUS 304) plate were carried out. It was revealed that a series of waves of metal jet are generated in the contact surface between both materials; and that the optimal collision velocity and collision angle is about 2,100~2,800 m/s and $15{\sim}20^{\circ}$, respectively. Also, explosive forming experiments of Al plate were performed and compared to a conventional press forming method. The results confirmed that the shock-loaded Al plate has a larger curvature deformation than those made using conventional press forming. For shock consolidation of powders, the propagation behaviors of a detonation wave and underwater shock wave generated by explosion of an explosive are investigated by means of numerical calculation. The results revealed that the generation and convergence of reflected waves occur at the wall and center position of water column, and also the peak pressure of the converged reflected waves was 20 GPa which exceeds the detonation pressure. As results from the consolidation experiments of metal/ceramic powders ($Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$), shock-consolidated $Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$ bulk without cracks was successfully obtained by adapting the suggested water container and strong bonding between powder particles was confirmed through microscopic observations.

• Journal of the Korean Wood Science and Technology
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• 제34권4호
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• pp.1-8
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• 2006

Anatomy of Quercus variabilis charcoal was investigated by scanning electron microscopy. Charcoal was prepared in an electric furnace under nitrogen gas atmosphere at $400^{\circ}C$, $600^{\circ}C$, $800^{\circ}C$, and $1000^{\circ}C$ for 10 min. The structure of charcoal was significantly affected by charring temperature. In cross section, charcoal prepared at $400^{\circ}C$ exhibited a smooth clean surface. As the charring temperature increased, the surface became more rough and increasingly disrupted. The cell walls appeared homogeneous and glass-like. Ray parenchyma cells showed very little separation from each other in radial section at $400^{\circ}C$. At $600^{\circ}C$ and above there is an apparent disintegration of the middle lamella, resulting in a separation of the ray cells. The $2{\sim}4{\mu}m$ wart-like protuberances were observed on the surfaces of the parenchyma cells. These structures were seen in charcoal prepared at all temperatures. Distinctive features can be seen in multiseriate rays as large crack and split. Rhomboidal crystals in crystalliferous cells had a smooth surface at $400^{\circ}C$ and $600^{\circ}C$, but the crystals had a sponge like appearance at $800^{\circ}C$ and $1000^{\circ}C$.

• Journal of the Microelectronics and Packaging Society
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• 제18권4호
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• pp.49-53
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• 2011

High-speed Cu filling into a through-silicon-via (TSV) and simplification of bumping process by electroplating for three dimensional stacking of Si dice were investigated. The TSV was prepared on a Si wafer by deep reactive ion etching, and $SiO_2$, Ti and Au layers were coated as functional layers on the via wall. In order to increase the filling rate of Cu into the via, a periodic-pulse-reverse wave current was applied to the Si chip during electroplating. In the bumping process, Sn-3.5Ag bumping was performed on the Cu plugs without lithography process. After electroplating, the cross sections of the vias and appearance of the bumps were observed by using a field emission scanning electron microscope. As a result, voids in the Cu-plugs were produced by via blocking around via opening and at the middle of the via when the vias were plated for 60 min at -9.66 $mA/cm^2$ and -7.71 $mA/cm^2$, respectively. The Cu plug with a void or a defect led to the production of imperfect Sn-Ag bump which was formed on the Cu-plug.

• Journal of the Korean Geotechnical Society
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• 제29권6호
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• pp.53-62
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• 2013

A 5-20 cm thick shocrete has been routinely constructed for NATM tunneling method to stabilize and confine the excavated rock of tunnel construction site. A $40kg/m^3$ of steel fibers are usually mixed into such shotcrete but these steel fibers may not be evenly distributed depending on shotcrete machines, mixing ratios and excavated rock conditions. In this study, square column shotcrete-mimicked concrete specimens of $15cm{\times}15cm{\times}55cm$ were prepared with 5 equal layers and 5 or 20% cement ratio. The specimens were prepared with different reinforced-patterns: non-reinforced, middle layer-reinforced, 1, 3, and 5 layers-reinforced, or all layers reinforced. The specimens were air-cured for 7 days and tested for flexural strength. The influence of steel-fiber distribution on flexural strength and toughness of shotcrete-mimicked concrete specimens was investigated. In the case of a specimen with cement ratio of 20%, a flexural strength increased as a number of fiber-reinforced layer increased. The flexural strength of one-layer reinforced specimen showed 20% less than that of evenly fiber-distributed specimen. On the other hand, a specimen with cement ratio of 5% decreased as the number of fiber-reinforced layers increased. A toughness index increased as the number of fiber-reinforced layers increased, regardless of cement ratios. The toughness index of evenly fiber-distributed specimen showed 2-3 times as large as that of one-layer reinforced specimen.

• Journal of Navigation and Port Research
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• 제44권4호
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• pp.305-311
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• 2020

Rising sea levels along the coast from global warming causes the increase of wave energy along the coast. This rise in sea levels results in relatively deep water levels, which would incur the loss of sand that had not occurred in the past from erosion in coastal areas. Generally, it has been challenging to protect against coastal erosion, and the slope, cross-sectional shape, and materials are selected for the site conditions depending on the change in external forces. However, the application of counter measures based on insufficient understanding of the phenomenon is causing various damage, indicating the need for technological development and converging technologies to improve credibility. In this study, we developed eco-friendly permeable biopolymer concrete blocks to control the coastal erosion by using the Bio-Coast, an effective porous structure that mitigates the destructive erosion caused by the rising sea levels. The hexagonal design of Bio-Coast was derived from the honeycomb, columnar joints, and clover, which are durable and stable structures in nature, and the design was changed to apply bumps on the Bio-Coast filling in the form of a clover to reduce wave overtopping and run-up. Applying the field condition of beaches on the east coast of Korea, the block weight and size were decided and the prototype blocks were manufactured and are ready for field placement. In particular, it is intended to protect coastal areas from destructive erosion by natural and artificial external forces, and to extend the design to river,s lakes, and natural walking trails, to improve the efficiency of quality control and process control through the use of blocks.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제21권9호
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• pp.979-986
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• 2010

This paper presents an algorithm for retrieving precise radar cross sections(RCS) of various trihedral corner reflectors (TCR) which are external calibrators of synthetic aperture radar(SAR) systems. The theoretical RCSs of the TCRs are computed based on the physical optics(PO), geometrical optics(GO), and physical theory of diffraction(PTD) techniques; that is, the RCS computation includes the single reflections(PO), double reflections(GO-PO), triple reflections(GO-GO-PO), and edge diffractions(PTD) from the TCR. At first, we acquire an SAR image of the area that five TCRs installed in, and then extract the RCS of the TCRs. The RCSs of the TCRs are extracted accurately from the SAR image by adding up the power spill, which is generated due to the radar IRF(Impulse Response Function), using a square window. We compare the extracted RCSs with the theoretical RCSs and analyze the difference between the theoretical and experimental RCSs of the TCR for various window sizes and various backscattering coefficient levels of the adjacent area. Finally, we propose the minimum size of the integration area and the maximum level of the backscattering coefficients for the adjacent area.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제19권6호
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• pp.126-136
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• 2018

A steel-plate concrete composite beam is composed of a steel plate, concrete and shear connector to combine inhomogeneous two materials. The steel plate is assembled by welding an existing composite beam. In this study, new steel-plate concrete composite beam, called a SPC Beam, was developed to reduce the shear connector and improve the workability. The SPC Beam was composed of folding steel plates and concrete, without a shear connector. The folding steel plate was assembled using high strength bolt instead of welding. To improve the workability in field construction, a hat-shaped Cap was attached to the junction with a slab. Monotonic load testing under two points was conducted under displacement control mode. The flexural strength of the specimen for positive moment and negative moment was calculated using the plastic stress distribution method. The test results showed that the flexural strength of the new SPC Beam had 80% of the strength of a complete composite beam. In addition, increasing the composite ratio was possible through clearance controls of the cap. In this study, the performance of the SPC Beam was verified through additional experiments and analyses with the cross-sectional shape and cap as variables, because the representative shape in the positive negative moment region is targeted.