• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.1051-1060
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• 2008

The use of the coal ash for surcharge material, in a view of the environmental aspect, can decrease amount of the reclamation through recycling waste materials as well as prevent a destruction of the ecosystem attributed to sand picking. In addition, it can reduce both unit cost of material and construction expenses. In this study, new construction material as alternative surcharge material using coal ash, which is by-product from thermoelectric power plant, were developed. Mixing ratios of fly ash and bottom ash derived from the coal ash in Samchunpo thermoelectric power plants were determined. Furthermore, mixing conditions depending on the ratios of the cement and gypsum used for chemical additive were determined too. Uniaxial compression strength tests were conducted at different mixing conditions and Design graph of optimum mixing ratio at each required strength for economic efficiency is indicated in this paper.

• 한국해양공학회지
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• 제23권5호
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• pp.54-60
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• 2009

Exposed to various environments, concrete confronts degradation by a lot of physical and chemical reaction. Though so many experiments and theorizations on the single condition of concrete degradation have been carried out by constant studies, the truth for now is that there are few studies on the compound phenomenon of degradation related with marine environments. Accordingly, this study measured the degree of degradation in the change of external shape, the change of unit weight and compressive strength, ultrasonic velocity test, and the change of length, etc. after exposing the specimen of cement mortar to the environment between 0 cycle and the maximum of 300 cycles under the condition of aquatic curing, freezing and thawing, and compound degradation, using mineral admixture effective for concrete degradation as a binder. The result indicated that the case of adding mineral admixture showed greater resistance than that of using OPC only, and specifically, the specimen with the additive of slag powder and three component system showed very excellent resistance to freezing and thawing, and compound degradation.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.45-51
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• 2009

A ground-loop heat exchanger in a ground source heat pump system is an important unit that determines the thermal performance of a system and its initial cost. The size and performance of this heat exchanger is highly dependent on ground thermal properties. A proper design requires certain site-specific parameters, most importantly the ground effective thermal conductivity, the borehole thermal resistance and the undisturbed ground temperature. This study was performed to investigate the effect of some parameters such as borehole lengths, various grouting materials and U-tube configurations on ground effective thermal conductivity. In this study, thermal response tests were conducted using a testing device with 9-different ground-loop heat exchangers. From the experimental results, the length of ground-loop heat exchanger affects to the effective thermal conductivity. Among the various grouting materials, the bentonite-based grout with silica sand shows the largest thermal conductivity value.

• 한국해양공학회지
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• 제19권6호통권67호
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• pp.72-77
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• 2005

The materials used in a ship screw propeller are commonly made with brass. The seawater corrosion and seawater cavitation of the screw propeller reduces the propulsive performance of the ship. In screw manufacturing, the corrosion rust of the screw propeller is removed through a hand grinding method. The grinding process produces dust of the heavy metals from the brass. The dust creates a poor working environment that is harmful to the health of the workers. An automatic corrosionrust removing apparatus, using a blasting method, was developed for the improvement of screw polishing conditions and its working environment. The performance of this apparatus was investigated by surface roughness, weight loss rate, hardness, electrochemical corrosion resistance, and cavitation erosion, after removing of the corrosion rust under various blasting conditions. Two medias of alumina and emery were used in this experiment. The surface roughness and hardness of the screw were improved by this apparatus. The electrochemical corrosion potential (Ecorr) and current density (Icorr) were measured by the dynamic polarization method, using a potentiostat,under the conditions of surface polishing with grinding, blasting, wire brushing, and fine sand papering. The test results prove that the new corrosion rust-removing apparatus improves the surface performance of a screw propeller.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2005년도 국제학술회의
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• pp.100-113
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• 2005

Leaf color and plant vigor are key indicators of crop health. These visual plant attributes are frequently used by greenhouse managers, producers, and consultants to make water, nutrient, and disease management decisions. Remote sensing techniques can quickly quantify soil and plant attributes, but it requires humans to translate such data into meaningful information. Over time, scientists have used reflectance data from individual wavebands to develop a series of indices that attempt to quantify things like soil organic matter content, leaf chlorophyll concentration, leaf area index, vegetative cover, amount of living biomass, and grain yield. The recent introduction of active sensors that function independent of natural light has greatly expanded the capabilities of scientists and managers to obtain useful information. Characteristics and limitations of active sensors need to be understood to optimize their use for making improved management decisions. Pot experiments involving sand culture were conducted in 2003 and 2004 in a green house to evaluate corn and red pepper biomass. The rNDVI, gNDVI and aNDVI by ground-based remote sensors were used for evaluation of corn and red pepper biomass. The result obtained from the case study was shown that ground remote sensing as a non-destructive real-time assessment of plant nitrogen status was thought to be a useful tool for in season crop nitrogen management providing both spatial and temporal information.

• 디지털콘텐츠학회 논문지
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• 제18권4호
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• pp.787-793
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• 2017

본 논문은 기존의 단순한 수위측정 방식과는 달리 저수지 및 사방댐 등의 담수량 및 토사의 퇴적량을 단위체적블록 객체모델링을 통하여 실시간 측정하고, 해당 정보를 영상 정보와 같이 제공하는 IoT기반 소규모 저수지/사방댐 담수량 및 토사량 모니터링 시스템을 제안한다. 제안 시스템은 점차 강화되고 있는 사방댐 관리규정과 함께 보다 정확한 준설계획의 수립과 효율적인 물 관리가 가능하고, 산사태 등의 재해사고 방지에 매우 효과적이다.

• 청정기술
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• 제12권4호
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• pp.238-243
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• 2006

본 연구에서는 용융 전로슬래그를 고속의 공기를 이용하여 급랭한 전로슬래그의 골제 특성을 조사하고 이를 잔골재로 재활용한 모르타르의 특성을 분석하였다. 급랭전로슬래그의 입자형태는 구형이었으며 냉각 속도의 차이로 인해 표면층과 내부층 그리고 외부와 연결된 공동을 가지고 있었다. 표준사를 구형 급랭전로슬래그로 대체한 혼합 잔골재의 특성을 분석한 결과 대체 비율이 증가하면서 비중, 단위용적중량 그리고 조립율이 증가하였으며 실적률은 대체 비율 75%에서 최대를 나타내었다. 흡수율은 대체 비율 50%에서 최소값을 보였다. 혼합 잔골재의 구형 급랭전로슬래그 대체 비율이 증가할수록 굳지 않은 모르타르의 유동성이 증가하여 동일한 플로우값을 얻기 위한 물/시멘트 비는 감소하였다. 구형 급랭전로슬래그 대체 비율이 증가할수록 양생한 모르타르 시편의 조직은 치밀하였으며 비중은 증가하였다. 압축강도의 경우는 대체율 75%에서 최대값을 보였다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.260-265
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• 2004

The materials of ship screw propeller are commonly the manganese bronze. The seawater corrosion and cavitation of the screw propeller reduce tire propulsive performance of ship. In screw manufactory, tire corrosion rust of tire screw propeller is removed by a hand grinding. The grinding work makes the dust of the heavy metals from the manganese bronze. The dust makes indoor working environment poor. A friendly-environmental and automatic corrosion removing apparatus was developed for the improvement of screw processing and working environment. The corrosion rust of a screw propeller was remarkably removed by using apparatus. And the screw surface roughness was improved by a blasting effect of the apparatus performance test. Anode polarization curves on jour processing conditions, that is to say, grinding, blasting, wire-brushing, fine sand papering, were confirmed by a potentiostat. Especially, two kinds of medias, alumina and emery, were used in the blasting processing. Then, investigated tire cavitation erosion of specimen. This result proved that tire blasting work has considerably improved the corrosion resistance of a screw propeller.

• 콘크리트학회논문집
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• 제11권3호
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• pp.123-130
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• 1999

In a preceding study(1), the using method of garnet powder has been studies through the various investigation of basic material properties on garnet powder, industrial by-products generated in Yungju, Kyungpook. In this study, the various properties of concrete mixed with garnet powder are examined as following condition : Unit weight of water (170kg/㎥), water-binder ratio W/B (53, 55 and 58%), sand-aggregate ratio (S/A) (43, 45 and 48%), substitutional ratio of garnet powder of 0, 5, 10, 15 and 20%. Slump increased a little as the substitutional ratio of garnet increased. Air content decreased a little at the substitutional ratio of 10%. or more. Though there is a little difference in compressive strength according to the W/B and the substitutional ratio, compressive strength of concrete using garnet exceeded that of plain concrete a little in the range of the substitutional ration of 5 to 15%. Also, There is a similar tendency in the tensile and flexural strength. Therefore, the use of garnet powder with industrial by-products is expected to improve the workability and the strength of concrete.

• 콘크리트학회지
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• 제8권2호
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• pp.109-117
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• 1996

최근 일본에서는 콘크리트의 성능을 향상시킨 고유동콘크리트에 대한 연구가 활발히 진해되어 일부 실용화단계에 와 있다. 그러나 국내에서는 이러한 고품질의 고유동콘크리트에 대한 연구가 극히 미진한 실정이다. 따라서 본 연구에서는 콘크리트의 유동성에 영향을 미치는 배합인자들의 특성을 파악하여 경제적이고 합리적인 배합방법으로 기존의 재료와 생산설비로서 고유동콘크리트 제조를 목포로 하였으며 아울러 실기시험 및 현장적용실험을 통해 고유동콘크리트의 현장적용 가능성을 평가하고자 한다. 연구결과 배합설계를 통해 기존의 재료와 생산설비로서 우수한 품질을 확보하면서 시공성면에서도 양호한 고유동콘크리트를 제조할 수 있음을 확인하였다.