• 한국지형학회지
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• 제26권1호
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• pp.15-26
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• 2019

In this study, we investigated the grain size, lithological type, and shape of coarse bed materials in the upper and middle reaches of Gongneungcheon River. For this purpose, 11 sampling points were selected along the river. For 100 samples of the coarse bed materials at each point, three axes (long, intermediate, and short) of samples were measured, and their lithological types were also identified. By measuring grain size, the sphericity and flatness of samples were calculated. Finally, every particle was classified into four shape categories: sphere, disc, blade and rod. We found that the grain size in incised meandering reach is the largest. This is mainly due to the supply of coarse materials from steep valley sides along the meandering channel. According to the lithological analysis, all samples were identified as granite, gneiss and schist, and quartz. The proportion of granite decreased, whereas the proportion of gneiss and schist increased downstream. These patterns indicate that the bedrock distribution within the study area accounts for the downstream lithological variation of coarse bed materials. With regard to the grain shape, sphericity gradually decreased while flatness gradually increased downstream. In the case of the shape classification, unlike the general downstream pattern of grain shape, the proportion of the sphere type decreased and the proportion of the blade type increased downstream. Such a reversal change in the downstream direction turns out to be determined by the lithology (such as foliation, bedding and the pattern of weathering) of coarse bed materials.

• 대한지리학회지
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• 제33권1호
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• pp.1-16
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• 1998

본 논문에서는 조립질 하상이 잘 발달된 로키 산맥의 소하천들을 대상으로 퇴적물의 입경과 유역 면적과의 관계, 그리고 퇴적물의 입경과 하도 경사와의 관계를 중점적으로 조사하였다. 조사 결과, 퇴적물의 입경은 유역 면적의 증대에 따라 지수적으로 감소되었으며, 산지와 평지의 지형 경계부를 기점으로 그의 상류와 하류간에 입경 변화의 경향성이 서로 달랐다. 하도 경사 또한 유역 면적의 증대에 따라 지수적으로 감소되었는데, 그 분포 패턴은 퇴적물 입경의 경우와 큰 차이가 없었다. 따라서 퇴적물 입경과 하도 경사는 매우 밀접한 관련이 있는 것으로 조사되었다. 이와 같은 조사 결과들을 유역 분지의 지형 및 지질 조건과 관련지어 고찰하여 볼 때, 본 지역에서는 높은 산지로부터 낮은 평지로 급격히 전환되는 지형 조건과 비교적 동질적인 지질 조건이 퇴적물의 입경 및 하도 경사에 영향을 미치고 있는 것으로 생각된다.

• 한국토양비료학회지
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• 제47권1호
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• pp.66-70
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• 2014

Bed-soils can be used to help plants to overcome unfavorable conditions of soils, especially hydraulic properties of soils. This study was conducted to evaluate the effect of organic and inorganic raw materials on saturated hydraulic conductivity ($K_s$) of bed-soils. Perlite and bottom ash, which are inorganic materials, increased more $K_s$ of bed-soils than coco peat, an organic material. However, vermiculite, an inorganic material, increased less than coco peat. Saturated hydraulic conductivity of bed-soil mixed with fine vermiculite ($0.14{\pm}0.02mh^{-1}$) was much lower than one containing coarse vermiculite ($0.85{\pm}0.21mh^{-1}$). Such effect was more apparent when pressure was added on bed-soils containing fine vermiculite ($0.07{\pm}0.01mh^{-1}$), probably reflecting the decrease in pore size with the expansion of vermiculite wetted. Compacting decreased more $K_s$ in the bed-soils containing coco peat or vermiculite than other mixtures. Those results suggest that perlite and bottom ash in bed-soils play an important role in improving saturated hydraulic conductivity but vermiculite in bed-soils may suppress the improvement of saturated hydraulic conductivity with the decrease of its size and with the increase of compacting pressure.

• 한국환경복원기술학회지
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• 제13권2호
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• pp.95-104
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• 2010

The purpose of this study is to analyze the correlation between physical stream characteristics and bed materials in natural rivers. Accordingly, four natural rivers were selected reference streams, they were Nam river, Sumjin River, Naesung River and Han River. Grain size distributions of bed materials were gravels, cobbles and boulders in Han river and Nam river, were sand, gravels, cobbles and boulders in Sumjin river and were sand in Naesung river. Four reference streams were divided into each two reference reaches (straight and bend) by plan and profile characteristics of naturally meandering stream. Therefore various reference reaches were chosen in the aspect of physical stream characteristics and grain size distributions. The results investigated and analyzed are as follows. The streams that grain sizes distributions of river bed materials were coarse were stable because they had variety of bed slope without sediment deposition, and then the riffles frequency and the physical characteristics were various. Also, velocitydepth regime were various in four kinds, and the response parts for water level change were small, so that channel flow status were stable and excellent condition. On the other hand, sand river that grain sizes distributions of river bed materials were fine had not the variety of parameters as velocity-depth regimes, sediment deposition, channel flow status and riffles frequency, so that the physical stream characteristics were not various.

• 물과 미래
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• 제26권1호
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• pp.103-114
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• 1993

수로의 형상과 하상조건에 따른 이행특성을 일정반경곡선(CRC), 정현곡선(SGC) 및 미소지폭파 이론(SWT)의 방법에 의해 연구하였다. 수로의 형상이 사행이고, 하상조건이 거친 하상입자인 사행하천의 경우에는 CRC 및 SGC의 방법을 적용하여 횡방향 하상경사, 수심 및 유속분포의 예측치를 구하고, 이를 실측치와 비교하였다. 또한 가는 입자의 준사행하천(Sinuous Channels)에 대해서는 SWT의 방법을 이용하여 횡방향과 흐름방향의 사행이행량을 각각 구하였다. 그 결과 횡방향 질량이송계수는 사행이행의 크기 및 방향을 결정하는데 중요한 계수임이 확인되었다.

• 한국안전학회지
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• 제14권3호
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• pp.101-109
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• 1999

This study attempts to analyse the solid mixing in the feeder and the packing effect for pressure fluctuations in the fluidized bed. To study the mixing characteristics of solid in vibrating feeder for the stable operations of fluidized combustion, the system consisted of two groups of particles such that fine particles were located on the top of the coarse particles before vibratory mixing had started. The effects of packing materials on the pressure fluctuations in a fluidized bed were analysed by using a statistical method to interpret the behavior of fluidized bed. The experiments were carried out in a fluidized bed of 6.7cm-ID, and the experimental variables were particle sizes, of 115 to 1,015$\mu\textrm{m}$ in diameter and the multi-sized particles haying Rosin-Rammler and Gaussian distributions. The settled bed heights of particles to diameter ratios (L/D) were ranged from 0.5 to 2.0. And fluidizing of particles was carried out by air. The packing materials used were screen packing, and the properties of the pressure fluctuations in the fluidized bed were measured by a differential pressure transducer. The properties of the pressure fluctuations calculated were the mean, the standard deviation, and the major frequency of the power spectral density functions. From the characteristics of fluidizing, it was found that the standard deviation of pressure fluctuations could be effectively used to explain the fluidized phenomena, and the packing materials affected severely the properties of the pressure fluctuations. As a result, from the interpretation by spectral analysis, the effects of measuring radius of pressure fluctuations on standard deviation were constant in the case of the fluidized bed with and without packing materials. However, the effects of measuring the height of pressure fluctuations on standard deviations were linear increasing for the fluidized bed with packing materials, but were constant for the fluidized bed without packing materials at 4.5cm above the gas distributor. The major frequency of pressure fluctuations was found to be nearly independent of fluidized system. Also, the major frequency of pressure fluctuations decreased with increasing packing size, and it had maximum value at 10% of the packing amount.

• 한국수자원학회논문집
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• 제37권5호
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• pp.387-395
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• 2004

본 논문에서는 하상변동 및 유사입자의 시간적 공간적 분포를 동시에 모의할 수 있는 2차원 수치모형을 제시하였다. 사행수로의 하상변동은 만곡부의 외측에서는 하상이 세굴되고 훨씬 더 거친 입경의 재료로 구성되며, 만곡부의 내측에서는 하상이 상승하고, 세립토로 구성되었다. 또한 사행하천에서 흐름의 방향에 대한 입자분포 과정은 상류의 변곡점에서 시작하여, 하류 변곡점에서 마치게 되는 것을 보여주었다. 하천의 경계가 불규칙하고 복잡한 하천에서는 혼합사호 형성된 하천에서보다 균일사로 이루어진 하천에서 하상이 깊게 세굴되는 현상을 보여준다. 혼합사로 이루어진 하천에서의 공간적 입도 분포는 사행하천에서와 마찬가지로 하상이 퇴적되는 사행의 내측에서는 세립토로 구성되고 하상이 세굴되는 외측에서는 굵은 입자로 구성되는 것을 보여주었으며, 하천 폭이 좁은 부분에서는 하상의 세출 및 하상재료가 굵게 변화되는 것을 보여주었다.

• 한국의류학회지
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• 제28권11호
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• pp.1353-1360
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• 2004

The purpose of this study is to develop a cultural products design of korean image using fabrics. The study is carry out in literature research methods and make sample product. We examine existing researches about cultural product design development to understand developed items, materials, and design directions. The brainstorming method and the established literature researches were used to obtain the design components of Korean image. A cultural products design was developed into the decorative structural details. The results can be summarized as follows: Korean image is pure, passive, gentle, small, and lasting life-force at weeds and wild flowers. Korean form is rounded curve and soft silhouette as streamy, not exaggerate. Korean color is not a finishing treatment, non-dyed natural color, or pastel, light greyish, and dull tone. Korean textile is a natural materials as linen, ramie, and coarse silk. Final sample products are table supplies, home goods and bed goods applying the sewing method of tuck, quilting, top-stitching, patch work, applique and embroidery.

• Korean Chemical Engineering Research
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• 제52권1호
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• pp.81-87
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• 2014

고체가 연속적으로 주입되고 배출되는 상온 상압 2단 기포 유동층(내경 0.1 m, 높이1.2 m)의 흐름특성을 조사하고, 운전유속범위를 고찰하였다. 고체는 상부 기포 유동층으로 주입되고, 넘쳐서 기계적 혹은 비기계적 밸브가 없이 단순히 농후상 고체 층으로 이루어진 고체 수송관(standpipe, 내경 0.025 m)를 통하여 하부 기포 유동층의 층으로 주입되며, 하부 유동층을 넘쳐서 고체가 배출되었다. 기체는 하부 유동층을 유동화하고 배출된 후 다시 상부 유동층을 유동화하였다. 기체로는 공기를 사용하였고, 고체로는 입도가 큰 입자(< $1000{\mu}m$, 겉보기 밀도 $3090kg/m^3$)와 입도가 작은 입자(< $100{\mu}m$, 겉보기 밀도 $4400kg/m^3$)를 혼합한 입자를 사용하였으며, 혼합비를 변수로 하였다. 하부 유동층 기체가 고체수송관의 고체흐름을 비우고, 우회하는 조건일 때 하부 유동층 유동화 속도를 붕괴속도로 정의하였다. 본 공정의 운전이 가능한 최대기체유속으로 붕괴속도가 사용될 수 있었다. 붕괴속도는 작은 입자 혼합비가 증가함에 따라 증가하여, 30%에서 가장 큰 값을 나타낸 후, 감소하였다. 붕괴속도의 경향은 고체수송관 상단과 하단 사이의 압력차 경향과 유사하였다. 붕괴속도는 벌크밀도(bulk density)와 정체층 공극률의 함수로 나타내졌으며, 벌크밀도가 증가하면 증가하고, 정체층 공극률이 증가하면 감소하였다.

• 산업기술연구
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• 제4권
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• pp.37-41
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• 1984

Deposits of SiC has been formed by a chemical vapor deposition technique involving the application of gaseous mixture of $CH_3SiCl_3$ (MTS) and $H_2$ onto graphite substrate. These are non-fluid bed deposits prepared in an induction-heated reactor. From the experimental results, the deposition reaction of SiC is controlled by surface reaction mechanism at the temperature range between $1,100^{\circ}C$ and $1,400^{\circ}C$. The morphology of the SiC deposits changes from amorphous type to coarse, faceted structure as temperature increase.