• Water for future
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• v.29 no.2
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• pp.221-233
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• 1996

To investigate the hydrodynamic characteristics of a two-dimensional buoyant surface jet, the most important factors of the numerical analysis are the evaluation of the free surface and the turbulence transportation under the stratification. In present study, a numeriacal simulation model used with the semi-implicit method for pressure-linked equations (SIMPLE), the non-hydrostatic approximation and the algebraic stress model (ASM) is applied to investigate the vertical structure of internal flow hydrodynamically. The ASM enables to take account of anisotropy of turbulence, the damping effects of the density interface, and the free surface on the turbulence structure accurately. The ASM tested produces better agreement than the $\kappa-\varepsilon$ model with measurements by Nakatsuji (1984) on the flow development and turbulence structure. Applicability of the ASM to a two-dimensional buoyant surface jet is examined through comparison with experimental data.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.03a
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• pp.475-479
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• 2004

위성에서 감지되는 조간대 원격 반사도는 함수율, 퇴적상, 지형과 생물체 등의 영향에 의해 결정된다. 따라서 다른 환경요인을 제거하지 않고 위성자료 값을 분류하여 퇴적상과 비교한다면 좋은 결과를 얻을 수 없다. 하지만 퇴적상과 다른 환경요인은 관계가 복잡하고 미묘하게 얽혀있기 때문에 위성 자료 값에서 정량적으로 분리하거나 고려하는 것은 매우 어렵다. 특히 mud flat의 조류로나 세곡 부분은 배수구배의 발달로 인해 표층이 빠르게 마르게 되어 매우 높은 광학 반사도를 보이고 이는 sand가 우세한 지역의 높은 광학반사도와의 구별을 어렵게 만든다. 따라서 본 연구에서는 위성자료의 원격반사도 값만으로 조간대의 표층 퇴적상을 분류할 경우 에러가 발생할 수 있는 이러한 문제를 해결하기 위하여 조간대 texture와 표층 퇴적상과의 관계를 파악하고자 한다. 6.6 m 해상도를 갖는 EOC 자료를 이용하여 조류로의 형태와 밀도를 알아내고, 현장에서 샘플 된 입도 자료를 분석하여 비교함으로서 상관관계를 알아보고자 한다. mud flat의 경우, 대부분 복잡한 texture 구조를 갖고 밀도가 매우 높게 나타났으며 mixed flat 지역에서는 직선 구조를 갖는 큰 조류로가 발달하며 일부지역에서는 표면수가 잔존함에 의해 조간대에서 가장 어둡게 나타났다. 반면 sand shoal 이나 chenier 등과 같이 sand의 함량이 매우 높은 곳에서는 지형이 높아 함수율이 매우 낮아 높은 광학 반사도를 보임을 알 수 있었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.425-428
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• 2019

본 연구에서는 남해 주변해역의 조석과 조류의 구조특성을 해석하기 위해 현장관측결과와 수치실험결과를 이용하였다. 남해 주변해역의 해수유동은 2003년~2008년 사이 노량수로, 대방수로, 여수수로, 창선수로, 강진만, 앵강만에서 ADCP 및 RCM 9 유속계를 사용하여 각 정점에서 1개월 정도 연속측류를 하였다. 노량수로와 대방수로에서는 ADCP를 사용하여 표층에서 저층까지 3m 간격으로 측류하였고, 여수수로, 창선수로, 강진만과 앵강만에서는 RCM-9 유속계를 사용하여 표층에서 연속 측류하였다. 노량수로 상층에서 동-서 방향의 최대 유속은 약 165~175 cm/sec, 대방수로에서는 창 낙조류 최대유속은 약 200~270 cm/sec, 여수수로에서는 약 85~96 cm/sec 정도 나타났다. 강진만의 표층에서 최대유속의 크기는 창 낙조류 비슷하게 35~46 cm/sec, 앵강만 입구 부근에서 낙 창조류 최대유속은 20~22 cm/sec으로 발생하였다. 또한, 조류수치모형실험을 수행하여 남해 주변해역의 조류분포 특성을 전반적으로 해석하였다.

• Journal of the Korean Wood Science and Technology
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• v.28 no.3
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• pp.1-8
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• 2000

To develop the technology of producing structural board from low grade materials, an attempt was made to produce strand/particle composites from split wood strand(S) and particle(P) of (Cryptomeria japonica D. Don), which changed the layer construction and the ratio of S/P. The influence of layer construction on board properties was determined, focusing on the number and alignment of the S layers. The effect of weight ratio of S/P (3:7, 1:1, 7:3) on mechanical properties was also discussed on seven layered panel. Mechanical properties were determined from static bending tests to give parallel and perpendicular modulus of rupture (MOR) and modulus of elasticity (MOE), and the internal bond (IB) strength. In general, the surface strand layers contributed to the MOR and MOE. The parallel MOR and MOE values were the largest for the single layered S panel (only Slayers: S1), but the perpendicular MOR and MOE was the smallest. Perpendicular MOR and MOE were the largest for seven layered composite that had two cross oriented strand layers (SPSPSPS: SP7). Specimens retained more than half of their MOE and MOR after two hours in boiling water and one hour soaking. IB was the largest for the panel having only P layers, however, differences in IB strength were not identified among the other multi-layered composite panels thus the effect of layer construction on IB strength was small. Thickness swelling (TS) and surface roughness were smaller for the composite having P layers on the surface than for those having S layers. The addition of strands did not enhance the mechanical properties (MOR, MOE, IB). TS values for the panels, with which the S/P ratio was over than 1:1, was the similar to the value for the single layered S panels.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.121-129
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• 2010

The purpose of this study is to present the resonable guideline of asphalt concrete pavements in apartment complex. To achieve this purpose was performed review of domestic and foreign guidelines, investigation of main distresses of asphalt concrete pavement, and structural analysis for the investigated cross-sections of the pavements in apartment complex. According to results of structural analysis, this study presented the standard cross-section of the pavement with subbase of 20cm, asphalt base of 5cm, and surface of 5cm in apartment complex. In urban areas, traffic is generally opened after asphalt base course is placed because of civil complaint by dust. Surface course is placed after all of work are completed. Considering these conditions, this study also presented the standard cross-section of the pavement with subbase of 20cm, asphalt base of 7cm, and surface of 5cm for urban areas that expect civil complaints by dust.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.4
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• pp.340-345
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• 1995

Dispersion characteristics of surface discharge heat water in shallow region are investigated for coastal power plant with nearly constant depth of 20 meters by observing the seasonal depthwide temperature in several stations, which give or precise horizontal distribution and vertical structure of heat water. Surface discharged heat water in shallow coast in the Yellow Sea relies mainly on ambient tidal flow. so it behaves as free jet when the ambient now is strong and shows plumelike behavior during stagnant tide. According to observation the neat field region is estimated as 200-300 meters and shows distinct vertical profile and exponentially decreasing pattern from discharge point for this region. But there are no remarkable vertical distortion of temperature beyond 800 meters even though it is discharged from surface. Characteristic length scale model, CORMIX3, is applied and compared with the field date Overall tendency of CORMIX3 results resemble well with field data especially in near field and intermediate region.

• Korean Journal of Food Science and Technology
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• v.14 no.4
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• pp.336-341
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• 1982

The histochemical examination of Undaria pinnatifida Laver were conducted with light microscope and electron microscope. The results obtained were as follow: 1. Undaria pinnatifida frond were composed with epidermis, cortex and medulla. But the cutting section of Undaria pinnatifida Laver showed that only the epidermal cell were bound to each other. The cortex and medulla of the frond were destroyed during U.P. Laver process. 2. To identification of bind material of U.P. Laver, which were treated with sodium carbonate solution for extraction of alginic acid and reacted with Periodic Acid Schiff(PAS) reagent. And the PAS reaction result was negative by light microscope observation. On this result, we found out that the alginic acid has the binder role of U.P. Laver. 3. Also, the bind structure of U.P. Laver were observed by electron microscope and could well find out the epidermal cell wall and bind position of alginic acid, which were could not observed by light microscope.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.4
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• pp.295-304
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• 2000

Vertical measurement of CTDT at about 30 min intervals and spatial surface temperature, salinity, and concentration of suspended particulate matters were conducted to elucidate the character of water column and the dispersal pattern in a floating ice-dominated fjord, Marian Cove, West Antarctica. Marian Cove showed two distinct water layers in terms of turbidity; 1) cold, fresh, and turbid surface plume in the upper 2 m,2) warm, saline, and relatively clean Maxwell Bay inflow between 15-45 m in water depth. Thermal melting of Maxwell Bay inflow and tidewater glacier/floating ices developed the surface mixed layer and the activity of floating ices cause Maxwell Bay inflow to be unstable. Due to the unstable water column, the development of Maxwell Bay inflow and subsequent surface plume are not influenced by tidal frequency. Coastal current generated by strong northwesterly wind may extend warm, saline, and turbid surface plume into the central part of the cove along the northern coast via the western coast of Weaver Peninsula. Terrigenous sediments of meltwaters from the glaciated ice cliffs near the corner of tidewater glacier and some coasts enter into the cove and their dispersion depends upon the hydrographic regimes (tide, wind, wave etc.). At the period of spring tide, the strong wind stress with the northwesterly wind direction reserve suspended sediment-fed surface plume and so allow the possibility of deposition of terrigenous sediments within the basin of cove.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.131-147
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• 2018

In the present study, the safety of the near surface disposal facility for low- and intermediate-level radioactive waste (LILW) is examined based on the fluid-flow simulation model. The effects of the structural design and hydrological properties of the disposal system are quantitatively evaluated by estimating the flux of infiltrated water at the boundary of the structure. Additionally, the safety margins of the disposal system, especially for the cover layer and vault, are determined by applying the various scenarios with consideration of possible facility designs and precipitation conditions. The overall results suggest that the disposal system used in this study is sufficiently suitable for the safe operation of the facility. In addition, it is confirmed that the soundness of both the cover layer and the vault have great impact on the safety of the facility. Especially, as shown in the vault degradation scenario, capability of the concrete barrier of the vault make more positive contribution on the safe operation of the facility compared to that of the cover layer.

• The Korean Journal of Petroleum Geology
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• v.10 no.1_2 s.11
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• pp.10-17
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• 2004

The Doowoo-ri tidal flat in the southwestern Korean coast is a typical open-coast tidal flat which has no barriers in the offshore such as barrier island and sand bars. The difference of induced wave energy with seasons is affected directly on the distribution of surface sediment and the formation of sedimentary structures because the sedimentation by wind wave is relatively much important element in this open-coast tidal flat. This open-coast tidal flat can be classified into tidal beach, intertidal flat and lower mudflat according to the pattern of geomorphology and sediment type. The intertidal flat can be again divided into 3 types: sand flat, mixed flat and mud flat based on the primary sedimentary structure and sand/mud ratio. Doowoori tidal flat shows a seasonal change in the surface sedimentary facies based on sediment composition and primary sedimentary structure. The change is closely related to the direction and magnitude of monsoon wind and also to storm frequency. In winter and spring, when northwesterly wind is most dominant and strong and also storms are common, sand-flat facies is largely distributed on the intertidal flat, whereas mud-flat facies is most dominant during summer when weak southeasterly wind is common. In the fall season, mixed-flat facies is dominant on the flat. The Doowoori intertidal flat is covered by mud sediment which is ca. 20 cm in thickness in summer season. In winter season, surface sediment is changed from mud to sand because the summer mud is mostly eroded by strong wave action. Can-core peels in the intertidal flat show that parallel laminated mud or sand/mud and climbing ripple cross-laminated sandy silt are dominant on the upper intertidal flat $(0-1.3 {\cal}km)$ during summer season. On the other hand, on lower intertidal flat $(1.7-2.3 {\cal}km)$, dominant sedimentary facies is homogeneous mud. In winter, it is changed into parallel laminated and ripple cross-laminated sand facies.