• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.77-86
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• 2013

This study investigates the fundamental properties of the water-binder (W/B) ratio and fine aggregate-binder (F/B) ratio in the alkali-activated slag cement (AASC) mortar. The W/B ratios are 0.35, 0.40, 0.45, and 0.50, respectively. And then the F/B ratios varied between 1.00 and 3.00 at a constant increment of 0.25. The alkali activator was an 2M and 4M NaOH. The measured mechanical properties were compared, flow, compressive strength, absorption, ultra sonic velocity, and dry shrinkage. The flow, compressive strength, absorption, ultra sonic velocity and dry shrinkage decreased with increases W/B ratio. The compressive strength decreases with increase F/B ratio at same W/B ratio. Also, at certain value of F/B ratio significant increase in strength is observed. And S2 (river sand 2) had lower physical properties than S1 (river sand 1) due to the fineness modulus. The results of experiments indicated that the mechanical properties of AASC depended on the W/B ratio and F/B ratio. The optimum range for W/B ratios and F/B ratios of AASC is suggested that the F/B ratios by 1.75~2.50 at each W/B ratios. Moreover, the W/(B+F) ratios between 0.13 and 0.14 had a beneficial effect on the design of AASC mortar.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.227-234
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• 2020

Under consideration of construction waste recycling, candidate secondary products applicable for the civil and construction areas can be reliably employed based on the recycling cost analysis. For the validation purpose, probability-based cost analyses were performed to estimate recycling cost profit considering uncertainties. When recycling construction wastes, the costs at each stage are fully dependent on target products to be adopted. To achieve commercialization of each product, its quality has to be improved with economic efficiency through accurate evaluation of input costs. Based on the probabilistic recycling cost analysis, the cost benefit for target products was estimated with waste classification cost, transportation cost to recycling treatment facilities and production cost. All necessary information on the cost analysis were collected from literature, disclosure, and existing recycling companies. In addition, a cost difference between recycled and non-recycled events was made. As a result, a probability-based recycling cost estimate for candidate secondary products was herein presented.

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.216-223
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• 2015

The conservation project to protect an endangered fish, Gobiobotia naktongensis was executed against declining the gene diversity of the fish after the construction of Youngju Dam in a sand-bed stream (Naeseongcheon Stream). We tried to move the populations of G. naktongensis from submerged planned sites to alternative habitats, bred artificially and augmented the juveniles to optimal habitat, and monitored the results of the restoration implementation. No entity of G. naktongensis was confirmed at the planned submerged sites despite attempting to capture more than 8 times and eventually the movement to alternative habitat could not be implemented. About 40 individuals of G. naktongensis were captured in the Naeseongcheon Stream and a total of 5,000 individuals were artificially spawned up. The population of juvenile inherited the genetic diversity from the brood stock. The bred juveniles were discharged at the selected optimal site that had a habit condition what was similar to their natural habitat. The micro-dispersion around the discharging area was found at the early stages of the augmentation. The re-capturing rate of discharged juveniles was reduced as time passed. The discharged juveniles seemed to adapt to the natural environment of Naeseongcheon Stream. The observation of their high abdominal distension and excrement demonstrated that the juveniles fed successfully in the discharging area. Therefore, securement of genetic homogeneity and enhancement of restoration population of G. naktongensis in upstream and downstream of Youngju Dam site from the artificial seed producing seemed to be primarily successful and long-term monitoring and analysis of the effect was expected to be necessary.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.3
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• pp.177-188
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• 2012

This study was mainly focused on the development of GIS based decision support system to easily make mitigation scenarios and to conveniently simulate water quality for TMDL. The study area was the 31km section of upper Sapgyo stream in Geum river basin, and QUAL2E model was adopted. GIS DB was built through the collection of the data which includes point/non-point source attributes and various thematic maps. The amounts of discharged loads of BOD, T-N and T-P from unit watershed were estimated respectively. Finally, the system, which can operate water quality simulation through simply modifying their values, was developed. The hypothetical three mitigation scenarios were applied, thereby the most efficient mitigation scenario could be chosen by comparison of the results based on GIS. Therefore, it is expected that the developed system can facilitate the decision makers to select the best alternative through the analysis of the available BMPs. Also, it can be used to develop new scenarios using different methods and algorithms. In the future, more study need to be made to enhance its applicability in the perspective of developing mitigation scenarios through the management of individual pollutant sources and extending study areas.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.11a
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• pp.48-48
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• 2011

국내 염색가공업에 종사하는 중소기업은 약 1,700여개 업체로써, 평균 50억/년 매출을 하고 있으며, 생산의 대부분을 임가공에만 의존하고 있는 실정이다. 이들 염색가공업체들은 섬유제품의 품질 향상 등을 위해 전처리, 염색, 가공이라는 섬유습식공정을 행하게 되는데 그 공정이 따로 분리되어 있어 임가공 업체 입장에서는 시간과 비용 차원에서 비효율적인 면이 존재하여 왔다. 따라서 공정합리화, 원가합리화를 위해 따로 분리되어 있는 위 공정을 통합하려는 시도를 많이 했지만 전처리/염색 공정의 통합에서 일부 성과가 있었을 뿐 효과면에서는 아직 미흡한 실정이다. 또한 가공이란 공정은 그사용 약제의 특수성에 따라 기존 Padding-Drying-Curing이라는 3 step process를 반드시 필요로 하고 있기 때문에 가공 공정의 통합은 시도조차 이루어지지 않고 있는 것이 현실이다. 따라서 염색공정과 가공공정의 통합을 시도하기 위해서는 관련 약제 개발이 출발이라 할 수 있으며 그 첫 대상은 염색 공정의 소핑과 가공공정의 유연처리를 동시에 행할 수 있는 소핑유연제로 선정하려 한다. 즉 셀룰로오스계 섬유의 반응성 염색 후 소핑 공정에서 일액형 소핑유연제, 한가지 제품만을 간편하게 사용해도 소핑효과와 유연효과를 동시에 얻어 후속 유연처리 공정을 생략할 수 있는 것이다. 그렇게 되면 시간적으로나 비용적으로 큰 절감 효과를 가져와 임가공 업체의 부담을 덜어 줄 수 있을 뿐만 아니라 공정 통합을 통해 배출되는 폐수의 양도 상당량 감소시킬 수 있을 것으로 기대된다. 본 연구 결과, 폴리옥시에틸렌 트리데실 에테르 타입의 계면활성제와 개질된 디메틸폴리실록산 계열의 실리콘 오일, 그리고 이들의 상용성을 확보하기 위한 특수 용제 및 첨가제를 최적의 비율로 배합하여 안정한 일액형 복합 소핑유연제를 제조할 수 있었다. 제조된 소핑유연제는 유백색 반투명 액상의 외관을 가지며 pH(10%solution)는 $7{\pm}1$, 고형분은 $13.5{\pm}0.5%$이었다. 이 소핑유연제의 성능 평가결과, 소핑력은 기존의 소핑제와 동등 수준으로 세탁견뢰도 4급이상의 성능을 보였고, 유연성 면에서도 기존의 유연제와 동등 수준으로 평가되었다. 이로써 기존의 분리된 소핑 공정과 유연공정을 개발된 제품을 이용하여 통합할 수 있어 염색현장의 비용절감, 공정단축의 효과를 기대할 수 있게 되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.378-385
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• 2017

This study investigated the design of a snap fit, which is widely used for fastening plastic parts. We analyzed the assembly mechanism of a lock snapfit, measured the assembly force and separation force based on the design of experiments, and derived a regression equation through an analysis of variance. The response surface methodology was also used. Polybutylene terephthalate was used to fabricate specimens, and the assembly force and separation force were measured using a micro-tensile tester. The length, width, thickness, and interference were considered as factors. A second-order regression model was used to derive the regression equation. The assembly force decreased with increasing length and width, but it increased with increasing thickness and interference. The finite element method was used to analyze the assembly mechanics. The width decreased the assembly force by increasing the ductility. The influences of the factors for low assembly force and high release force were shown to be opposite to each other. It was necessary to design a structure that minimized the assembly force while maintaining an appropriate level of separation force.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.3
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• pp.141-150
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• 2002

This study was conducted to reveal the effects of local climatic conditions on the yearly cone production in progeny test stand of Korean white pine. For this, yearly cone production by locality of progeny test stands was first measured and analyzed. The effects of climatic conditions on the cone production was analyzed by the estimation of yearly local climates based on both a topoclimatological method and a spatial statistical technique. From yearly climatic estimates, 19 climatic indices affecting cone production were computed for each of the progeny test stand. The yearly cone productions were then correlated with and regressed to the climatic indices to examine effects of local climatic conditions on the reproductive growth. According to correlation analysis, it was found that some typical climatic indices by locality were significantly correlated with the cone production. Also, the optimal regression equations which can estimate cone production by local climatic conditions were provided for applying to each of the progeny test stand of Korean white pine.

• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.539-544
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• 2015

There is drift toward moving offshore structures operating sites to deep water that brings subsea systems and types of apparatus to meet more severe environment than onshore. At this moment, climatic condition and seabed state affect trenching efficiency so trenching process is need to make steady progress in a short time. This paper is research on estimation about construction performance of waterjet trenching machine mounted on ROV trencher. Optimal number of nozzles that can maximize trenching efficiency is selected by considering clearance and angle of nozzles through CFD. Then verified effectiveness of waterjet apparatus on the result of trenching depth and velocity by model test analogized performance for construction work of waterjet trenching machine.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6360-6367
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• 2015

The location selection of the element that should guarantee easy visual perception, like the landmark, is the a topic that appears much in the design process. Recently, a graph analysis technique using computers has been applied in order to evaluate the visibility of the visual element, but the analytic frame is flat and the setting of the visual pont and the matrix are fixed so there were great limitations in obtaining the results of the practical analysis. Thus, this study presented Nondirectional Multi-Dimensional Calculation (MDVC-N), an analytic methodology available for the analysis of the dynamic visual point in the 3D environment. It thus attempted to establish the analytic application using the 3D computer graphics technology and designed a script structure to set the visual point and the matrix. In addition to that, this study tried to verify the analytic methodology by applying the complex land as an example model, where buildings in various heights of terrains with a high-differences are located, verifying the same analytic methodology. It thus tried to identify the visual characteristics of each alternative location. The following results were gained from the study. 1) The visibility can be measured quantitatively trough the application of the 6-alternatives. 2) Using the 3dimensional graph, intuitive analysis was possible. 3) It attempted to improve the analytic applicability by calculating the results corrected as a variable behavior from the local integration variable of the space syntax.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.2
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• pp.133-144
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• 2006

In order to catch out such Bond Strength, the preceding researchers had ever examined the Bond Strength of FRP Plate through their experimentations by setting up of various fluent. However, since the experiment for research on such Bond Strength takes much of expenditure for equipment structure and time-consuming, also difficult to carry out, it is conducting limitedly. This Study purposes to develop the most suitable Artificial Neural Network Model by application of various Neural Network Model and Algorithm to the adhering experiment data of the preceding researchers. Output Layer of Artificial Neural Network Model, and Input Layer of Bond Strength were performed the learning by selection as the variable of the thickness, width, adhered length, the modulus of elasticity, tensile strength, and the compressive strength of concrete, tensile strength, width, respectively. The developed Artificial Neural Network Model has applied Back-Propagation, and its error was learnt to be converged within the range of 0.001. Besides, the process for generalization has dissolved the problem of Over-Fitting in the way of more generalized method by introduction of Bayesian Technique. The verification on the developed Model was executed by comparison with the resulted value of Bond Strength made by the other preceding researchers which was never been utilized to the learning as yet.