• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.2
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• pp.297-305
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• 2016

This study aims to analyze characteristics of environmental load for the construction phase of PSC beam bridge based on Life Cycle Assessment. For detail computation of environmental load, the construction materials and energy consumption are derived from the BOQ, also connecting with environmental load by Korea LCI Database Information Network. The characteristic of environmental impact was analyzed by 25 cases and cut-off ratio was 80% to 94%. The result sorted by construction materials revealed that environmental load were 53.3% for ready-mixed concrete, 9.6% for wire rod, 7.8% for rebar, 6.8% for cement, 5.5% for plywood, and 5.2% for energy. Furthermore, the result of environmental impact revealed that 45.5% for global warming, 30.4% for abiotic resources depletion, 10.5% for human toxicity, and 8.9% for photochemical oxidant creation. In the future, we can make a decision considering environmental load based on LCA at design phase.

• Journal of Navigation and Port Research
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• v.28 no.1
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• pp.23-29
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• 2004

This paper deals with Reed-Solomon Coding for EUROFIX system EUROFIX is an integrated navigation and communication system, which combines Differential GNSS and Loran-C EUROFIX transmits DGNSS(Differential Global Navigation Satellite Systems) (data by pulse position modulation of Loran-C pulses. Loran-C system is regarded as a satellite backup system in recent. And now, it is important to detect and correct much errors in communication systems. Error corrections or correction algorithm is actively studied nowadays because of this. In this paper, we study and design encoder and decoder of Reed Solomon Code using Finite Galois Field Fourier Transformation for error corrections in EUROFIX data transmission. Through extensive simulation, the designed Reed Solomon code is shown to be effective for error correction in EUROFIX data transmission.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.54-54
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• 2011

홍수로 인한 인적 물적 피해는 국가 및 지방자치단체의 치수방재노력에도 불구하고 매년 끊이지 않고 발생하고 있다. 다행히 인명피해의 경우 1970, 80년대 연간 300명 규모에서 2000년대에는 150명 가량으로 줄고 있으나, 재산상의 피해는 매년 증가하고 있는 실정이다. 또한 과거 자연재난에 의한 홍수피해에 기후변화라는 외부요인이 추가적으로 발생하고 있는 실정이며, 국가 경제 발전 및 노령화 사회로 인한 홍수취약인구 증가로 좀 더 적극적인 방재대책이 필요할 것으로 판단된다. 이러한 방재대책 등의 국가정책 수립을 위해서는 장래의 홍수피해 예측이 무엇보다 필요하게 되는데, 현재까지는 홍수피해의 빈도분석 등을 통해 이러한 예측이 이루어지고 있다. 그러나 기후변화라는 외생변수는 과거 자료의 확률적 특성을 마비시켜 이러한 방법론들은 효용성을 잃게될 것으로 전망된다. 홍수피해액을 산정하는 방법은 일반적으로 2005년 이후 하천설계기준에서 채택하고 있는 다차원법을 많이 사용하고 있는데, 이 방법은 침수구역의 물리적 피해를 고려할 수 있어 비교적 정확한 홍수피해액을 산정할 수 있는 것으로 알려져 왔다. 그러나 이 방법을 적용하기 위해서는 정확한 침수심 산정이 무엇보다 필요하게 되는데, 이를 위해서는 지리정보체계(GIS)와 수리모형의 연계가 필수적이다. 따라서 이 방법은 주로 중소유역단위의 취수사업에 적용되어 왔다. 그러나 정책결정에 필요한 대규모유역 또는 지자체단위의 피해비용 산정에의 적용은 한계를 갖게 된다. 따라서 본 연구에서는 향후 기후변화 시나리오에 적용이 가능하도록 과거 홍수피해자료와 호우사상의 강우특성을 중심으로 양자간의 히스토그램 분석을 실시하였다. 또한 실제 홍수피해 조사자료는 대부분 지방자치단체별로 조사가 되고 있는 실정이므로 본 연구에서도 행정구역별로 분석을 수행하였다. 분석 결과 지자체별 전체 피해액은 발생횟수가 높은 중규모 호우사상으로 인한 비중이 가장 높게 나타나고 있으며, 국가에서 집중해야할 치수대책 수립 대상 규모도 이를 중점적으로 고려하여야 할 것으로 판단된다.

• Tunnel and Underground Space
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• v.13 no.2
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• pp.87-99
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• 2003

Geostatistics is defined as the theory of modeling of regionalized variables and is an efficient and elegant methodology for estimation and uncertainty evaluation from limited spatial sample data. In this study, we have made a theoretical comparison between kriging estimation and geostatistical simulation methods. Kriging methods do not preserve the histogram of original data nor their spatial structure, and also provide only an incomplete measure of uncertainty when compared to the simulation methods. A practical procedure of geostatistical simulation is suggested in this study and the technique is demonstrated through an application, in which it was used to identify the spatial distribution of RMR as well as to evaluate the spatial uncertainty. It is concluded that the geostatistical simulation is the appropriate method to quantify the spatial uncertainty of geotechnical variables such as RMA. Therefore, the results from the simulation can be used as useful information for designer's considerations in decision-making under various geological conditions as well as the related terms of contract.

• School Mathematics
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• v.5 no.4
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• pp.477-506
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• 2003

In this paper, we analyze nine-grade students' conceptions of parameters, their relation to unknowns and variables and the process of understanding of letters in problem solving of equations and functions. The roles of letters become different according to the letters-used contexts and the meaning of letters Is changed in the process of being used. But, students do not understand the meaning of letters correctly, especially that of parameter. As a result, students operate letters in algebraic expressions according to the syntax without understanding the distinction between the roles. Therefore, the parameter of learning should focus on the dynamic change of roles and the flexible thinking of using letters. We develop a self-regulation model based on the monitoring working question in teaching-learning situations. We expect that this model helps students understand concepts of letters that enable to construct meaning in a concrete context.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.866-869
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• 2015

With the advance in semiconductor technology, the number of elements that can be integrated in system-on-chip(SoC) increases exponentially, and thus voltage scaling is indispensable to enhance energy efficiency. Near-threshold voltage computing(NTC) improves the energy efficiency by an order of degree, hence it is able to overcome the limitation of conventional super-threshold voltage computing(STC). Although NTC-based low performance manycore system can be used to maximize energy efficiency, it demands more number of cores to sustain the performance, which results in considerable increase of area. In this paper, we analyze NTC manycore architecture considering the trade-offs between performance, power, and area. Therefore, we propose an algorithmic methodology that can optimize power consumption and area while satisfying the required performance by determining the constrained number of cores and size of caches and clusters in NTC environment. Experimental results show that proposed NTC architecture can reduce power consumption by approximately 16.5 % while maintaining the performance of STC core under area constraint.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.6
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• pp.156-168
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• 2017

Personal mobility (PM) can increase the mobility of individual, so that the elderly can be set as the target group for using PM because of relatively low walking ability to normal. In this study, we design PM device for elderly that can be used safely in the walking environment such as sidewalk. There are various obstacles in the walking environment, so the device must have mechanical performance to overcome all of them. In this study, we survey the status and level of obstacle factors in walking environment to determine the dynamic performance of the PM device for elderly. We check up several guidelines about walking facilities to define obstacle points for the device, establish field survey methodologies, and conduct field survey for some specific road sections. Based on the survey results, we confirm the possible problems that could arise when the dynamic performance of the device is selected based on the facility-related criteria. We also define the performance requirements for the device based on the requirements for electric wheelchair.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.128-137
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• 2011

The purpose of the FAPIS(Forest Aerial Photograph Interpretation System) development is to increase accuracy and efficiency of the digital forest cover type mapping for improving conventional analog-based mapping procedures by optimizing work-flow and mapping technology. The database models including digital forest cover type map, aerial photograph, and topographic map were designed for use in this system construction. The interface configured concisely to connect with functions such as search engine, display control, conversion to stereo interpretation mode, modification tools, automation of print layout and database models. It is expected that the standardization methodology based on this system can be applied and extended in making all kinds of digital thematic maps, providing decision-making and information of forest resources.

• Geotechnical Engineering
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• v.2 no.3
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• pp.37-50
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• 1986

The uncertainties encountered in the stability analysis for the foundation of offshore structures on clay are formulated in probabilistic terms and used to evaluate the reliability of the foundation design. The major sources of uncertainty are: soil properties, f.ave loads, and methods of analysis. The major part of the uncertainty in safety factor is contributed by the uncertainty in the undrained shear strength. All sources of uncertainties that affect the shear strength of clay are modeled and systematically analyzed. The in situ undrained shear strengths are evaluated by laboratory tests and cone penetration tests. The undrained shear strengths from the laboratory test and CPT, respectively at Statfjord B site in the North Sea, are used as an example in risk analysis. Using the CPT alone, the failure probability on sliding of gravity platform at Statfjord B is much larger than the failure probability using the laboratory undrained shear strengths. The major uncertainty of using the CPT as the estimate of th2 undrained shear strength of clay results from the correlation between the cone resistance and the undrained shear strength.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.91-91
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• 2017

전 세계적으로 인공습지는 도시화, 기후변화 및 생활수준 향상으로 인한 홍수와 가뭄, 하천생태계 변화, 수질오염과 같은 환경문제의 해결방안으로 제시되고 있다. 이에 따라 국내에서도 여러 목적과 형태의 인공습지가 조성되고 있다. 인공습지의 경우 특정 기능을 목적으로 하여 조성하더라도 인공적 생태계가 조성되므로 복합적 기능을 갖게 된다. 하지만 현재까지의 인공습지 조성 효과에 관한 연구는 한가지 기능에만 초점을 맞추어서 실제 인공습지 조성의 가치가 저평가되고 있다. 본 연구에서는 하천변 인공습지 조성에 따른 여러 효과 중 가장 주가 되는 홍수저감 및 수질개선 기능에 대한 효과를 분석하고 이에 따른 편익을 산정하였다. 먼저 인공습지의 적용 대상 유역을 선정하고 유역 내에 입지를 결정하여 이에 맞는 인공습지를 설계 및 적용하였다. 인공습지 조성에 따른 홍수저감 효과 및 수질개선효과를 각각 분석하였다. 분석 결과에 대해 MD-FDA를 통해 홍수피해액을 산정하였고 대체비용법을 통하여 동일한 수질개선 효과를 갖는 하수처리시설의 하수처리비 및 운영관리비에 해당하는 수질개선 편익을 산정하였다. 본 연구를 통해 인공습지의 홍수저감 효과뿐만 아니라 수질개선 효과를 확인하였으며 정량적인 분석방법을 통해 두 가지 기능에 대한 효과를 분석하여 보았다. 또한 산정된 홍수저감 및 수질개선 효과를 경제적 가치로 환산하여 보다 객관적인 지표로 나타내었다. 본 인공습지 조성에 따른 종합적 편익 산정 연구 결과는 다목적의 인공습지를 적재적소에 적용하는데 기여할 것이다. 추후 생태적 기능, 레크레이션 기능 등에 따른 기타 편익 산정 방법론 조사를 통해 각 기능의 편익을 추가한다면 인공습지 조성에 따른 편익을 종합적으로 고려할 수 있을 것으로 판단된다. 또한 인공습지 조성의 소요사업비 및 유지관리비를 산정하여 인공습지 조성에 대한 경제성분석을 한다면, 실제 인공습지 조성 사업 시 사업의 타당성을 평가하는 기초자료로 활용할 수 있을 것으로 기대된다.