• 지질공학
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• 제20권2호
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• pp.155-167
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• 2010

사면의 안정성 분석에 결정론적인 방법이 최근까지 많이 사용되어 왔으나, 암반의 불확실성과 가변성을 고려하는 확률론적인 방법이 더욱 효과적인 것으로 알려지면서 확률론적인 방법의 사용이 점차 증가하는 추세이다. 그러나 현재까지의 방법들은 절리의 특성이나 암반의 풍화 특성 등과 같은 암반의 특성이 사면 전체에서 균질한 것으로 가정하고 있으며, 암반 사면의 파괴에 가장 결정적인 변수인 절리의 연장성을 고려하지 않은 상태에서 안전율 혹은 파괴확률을 계산하여 사면의 안정성을 분석하고 있어서 정확한 사면 안정성 분석에 한계를 보이고 있는 실정이다. 이 연구에서는 모델 사면을 설정한 후, 사면이 균질하다고 가정한 경우와 사면을 암반 및 절리의 상태에 따라 구역으로 분할한 경우의 파괴확률을 계산하여 비교하였고, 또한 위의 각각의 경우에 절리의 연장성을 변수로 고려한 파괴확률을 계산하였다. 또한 강원도 홍천군에 위치한 사면을 구역으로 분할한 후 절리의 연장성을 고려한 파괴확률을 계산하여 모델 분석의 적용성을 검증하였다.

• 한국대기환경학회지
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• 제27권5호
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• pp.580-602
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• 2011

Volatile organic compound (VOC) emissions in the 2007 CAPSS (Clean Air Protection Supporting System) emissions inventory are chemically speciated for the SAPRC99 (Statewide Air Pollution Research Center 99) mechanism, following the Source Classification Code (SCC) matching method to borrow the U.S.EPA's chemical speciation profiles. CMAQ simulations with High-order Direct Decoupled Method (HDDM) are in turn applied to evaluate uncertainty in the method by comparing the simulated model VOC species to the observations in the Seoul Metropolitan Area (SMA) for a 2007 June episode. Simulations under-predicted ALK1 to ALK4 in SAPRC99 by a factor of 2 to 5 and over-predicted ALK5 by a factor of 7.5 while ARO1, ARO2, OLE1, and ethylene (ETH) are comparable to the observations, showing relative difference by 10 to 30%. OLE2 emissions are roughly 4 times overestimated. Emission rates for individual VOC model species are revised referring to the ratio of simulated to observed concentrations. Impact of the VOC emission changes on the overall ozone prediction was insignificant for the days of which 1-hr maximum ozone are lower than 100 ppb. However, simulations showed ozone difference by 5 to 10 ppb when high ozone above 120 ppb was observed in the vicinity of Seoul. This result suggests that evaluations on individual model VOC emissions be necessary to lead ozone control plans to the right direction. Moreover, the simulated ratios of ARO1 and ARO2 to $NO_x$ are roughly 50% lower than the observed ones, which imply that adjustment in $NO_x$ and VOC emission rates may be required to mimic the real VOC/$NO_x$ condition over the area.

• 기술혁신연구
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• 제13권2호
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• pp.97-131
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• 2005

This paper has discussed several issues regarding the barriers and opportunities for technological catch-up by the late-comer countries and firms. As one of the barriers to technological catch-up, the paper emphasizes the uncertainty involved with the third stage of learning how to design. The barriers arise because as the forerunner firms refuse to sell or give license to successful catching-up firms who thus have to design the product by themselves. The paper discusses how to overcome this barrier. It also notes that if the crisis of design technology is a push factor for leapfrogging, arrival of new techno-economic paradigm can serve as a pull factor for leapfrogging, serving as a winder of opportunity. The, it emphasized the two risks with leapfrogging, namely the risk of choosing right technology or standards and the risk of creating initial markets, and how to overcome these risks. It discusses how to overcome these risks in leapfrogging, and differentiates diverse forms of knowledge accesses. Then, the paper takes up the issue of whether there can be a single common or several models for catch-up. A common element of catching-up is to enter new markets segments quickly, to manufacture with high levels of engineering excellence, and to be first-to-market by means of the best integrative designs. This observation is supported by the fact that Korea and Taiwan has achieved higher levels of technological capabilities in such sectors as featured by short cycle time of technology. The possibility of two alternative models for catch-up is also discussed in terms of the key difference between Korean and Taiwan, especially in the position toward the source of foreign knowledge and the paths taken toward the final goal of OBM. Taiwan followed the sequential steps of OEM, ODM and OBN, in collaboration or integration with the MNCs. Korean chaebols jumped from OEM directly to OBM even without consolidating design technology.

• 한국전산구조공학회논문집
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• 제16권3호
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• pp.281-290
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• 2003

Co Evolutionary Structural Design(CESD) Framework is presented, which can deal with the load design and structural topology design simultaneously. The load design here is the exploration algorithm that finds the critical load patterns of the given structure. In general, the load pattern is a crucial factor in determining the structural topology and being selected from the experts어 intuition and experience. However, if any of the critical load patterns would be excluded during the process of problem formation, the solution structure might show inadequate performance under the load pattern. Otherwise if some reinforcement method such as safety factor method would be utilized, the solution structure could result in inefficient conservativeness. On the other hand, the CESD has the ability of automatically finding the most critical load patterns and can help the structural solution evolve into the robust design. The CESD is made up of a load design discipline and a structural topology design discipline both of which have the fully coupled relation each other. This coupling is resolved iteratively until the resultant solution can resist against all the possible load patterns and both disciplines evolve into the solution structure with the mutual help or competition. To verify the usefulness of this approach, the 10 bar truss and the jacket type offshore structure are presented. SORA(Sequential Optimization & Reliability Assessment) is adopted in CESD as a probabilistic optimization methodology, and its usefulness in decreasing the computational cost is verified also.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2004년도 제5회 정기학술발표대회 논문집
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• pp.584-587
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• 2004

우리나라 건설산업의 환경은 IMF를 기준으로 급격하게 변화하였다. 정부의 제도적인 보호막과 일부 관행으로 인해 안정된 환경을 보장받아왔으나 최근 대형 공공공사의 발주물량의 감소와 더불어 시장예측의 불확실성 증대, 공공공사의 효율화 및 투명성 제고를 위한 입 $\cdot$ 낙찰 제도의 개선, 업체의 급격한 증가 등의 이유로 건설업계 경쟁은 더욱 치열 해졌다. 이러한 경쟁의 심화는 조직구조가 취약하고 기술, 자금 등 경영자원이 부족한 중 $\cdot$ 소규모 건설업체가 환경변화에 신속히 대응하고 원가 절감 및 생산성 향상을 위한 지속적인 투자와 건설시장에서 살아남기 위한 전략수립을 요구하고 있다. 이러한 전략수립을 위해서는 건설기업들의 평가할 수 있는 기준을 마련하여야 한다. 이에 본 연구에서는 중규모 건설기업의 전략수립을 위한 기초적 연구로써 건설산업의 환경변화에 대응한 건설업체 평가기준을 제안하고자 한다.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.255-259
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• 2002

To reduce the uncertainty in the calibration of radiation beams, absorbed dose to water for high energy electrons is recommended as the standards and reference absorbed dose by AAPM Report no.51 and IAEA Technical Reports no.398. In these recommendations, water is, defined as the reference medium, however, the water substitute solid phantoms are discouraged. Nevertheless, when accurate chamber positioning in water is not possible, or when no waterproof chamber is available, their use is permitted at beam qualities R$\_$50/ < 4 g/cm$^2$ (E$\_$0/ < 10 MeV). For the electron dosimetry using solid phantom, a depth-scaling factor is used for the conversion of depth in solid phantoms to depth in water, and a fluence-scaling factor is used for the conversion of ionization chamber reading in plastic phantom to reading in water. In this work, the properties, especially depth-scaling factors c$\_$p1/ and fluence-scaling factors h$\_$pl/ of several commercially available water substitute solid phantoms were determined, and the electron dosimetry using these scaling method was evaluated. As a result, it is obviously that dose-distribution in solid phantom can be converted to appropriate dose-distribution in water by means of IAEA depth-scaling.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.294-297
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• 2002

For the quality control procedure of diagnostic x ray units, a method for simultaneous measurement of air kerma, half value layer and tube potential was developed utilizing a computed radiography system for intraoral radiography and film badge case. The response of average pixel values under the windows were calibrated by x rays generated at tube potentials from 40 to 140 kV with filtration from 1.5 to 3.7 mmAl. The calibration curves for half value layer and tube potential were derived as functions of attenuation factors by the 1.4 mmAl filter and the 0.2 mmCu filter. The energy dependency of the open window response was corrected by the calibration factor as a function of the attenuation factor by the 1.4 mmAl filter. The uncertainty of the estimated half value layer, tube potential and air kerma were 0.2 mmAl, 3.6 % and 5 %, respectively. It was thus suggested that this system could be applied to quality control program to detect the variation of working condition of x ray units in clinical use.

• 한국터널지하공간학회 논문집
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• 제10권1호
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• pp.1-15
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• 2008

터널과 같은 지하구조물의 경우에는 지반의 다양한 변동성과 불확실성으로 인하여 터널 시공단계에서의 위험이 계속적으로 종가하고 있으므로, 터널 설계단계에서 터널 안정성 및 환경성에 영향을 주는 위험요소에 대한 위험도 평가 및 관리가 매우 중요하다. 본 연구에서는 터널굴착으로 인한 안정성에 대한 위험도 분석을 지반자체의 지보능력, 지반침하에 의한 인접구조물 손상, 막장내 지하수 유입량, 지진영향 등의 요소로 구분하여 평가하였다. 또한 환경성에 대한 위험도 분석을 발파로 인한 소음 진동, 운영중 열차운행으로 인한 소음 진동, 지하수위 저하로 인한 환경영향 등으로 평가하였다. 이와 같은 위험요소들에 대하여 위험도를 정량적으로 평가하고 터널 전구간에 걸친 위험도의 분포특성을 파악하였다. 또한 다양한 확률론적 기법과 통계자료를 사용하여 각각의 위험도에 대한 비용(cost)을 분석하므로서 위험도가 터널공사에 미치는 영향을 평가하였다. 그리고 본 위험도 평가기법을 터널설계단계에서 적용하므로서 기존의 방법을 보완할 수 있는 보다 합리적인 위험도 평가방법으로서의 유용성을 검토하였다.

• 한국항공우주학회지
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• 제31권5호
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• pp.63-71
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• 2003

본 논문에서는 몸체진동형 링레이저 자이로에서 몸체진동을 검출하기 위한 각속도 센서 출력을 V-F 변환하여 링레이저 출력에서 몸체진동에 의한 출력을 제거하는 dither-stripping 방법에 대하여 논의하였다. Dither-stripping에서는 V-F 출력펄스와 링레이저 출력펄스간의 환산계수를 산출하는 방법과 V-F 출력펄스의 offset를 보정해주는 방법이 중요하다. 각속도 센서의 출력을 V-F 변환하여 dither-stripping하는 경우에는 offset을 보정하는 과정에서 몸체진동의 진폭잡음에 의한 자이로 출력의 오차가 크게 발생한다. 우리는 V-F 출력펄스를 미분하여 offset을 제거하는 방법을 고안하였다. 이를 위해서는 각속도 센서의 출력을 90deg 위상 이동시켜서 각도신호를 만들고 V-F 변환해야 하며 링레이저 출력의 위상도 샘플링의 반주기만큼 이동시켜야 한다. 그리고 두 펄스간의 환산계수는 분산을 이용하여 산출하였다. 이러한 각도신호 미분방식의 dither-stripping에 의하여 개선된 결과를 얻을 수 있었다.

• 환경영향평가
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• 제9권3호
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• pp.203-214
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• 2000

Health risk assessment is applied to streamlining LCA(Life Cycle Assessment) using Monte carlo simulation for probabilistic/stochastic exposure and risk distribution analysis caused by data variability and uncertainty. A case study was carried out to find benefits of this application. BTC(Benzene, Trichloroethylene, Carbon tetrachloride mixture alias) personal exposure cases were assumed as production worker(in workplace), manager(in office) and business man(outdoor). These cases were different from occupational retention time and exposure concentration for BTC consumption pattern. The result of cancer risk in these 3 scenario cases were estimated as $1.72E-4{\pm}1.2E+0$(production worker; case A), $9.62E-5{\pm}1.44E-5$(manger; case B), $6.90E-5{\pm}1.16E+0$(business man; case C), respectively. Portions of over acceptable risk 1.00E-4(assumed standard) were 99.85%, 38.89% and 0.61%, respectively. Estimated BTC risk was log-normal pattern, but some of distributions did not have any formal patterns. Except first impact factor(BTC emission quantity), sensitivity analysis showed that main effective factor was retention time in their occupational exposure sites. This case study is a good example to cover that LCA with probabilistic risk analysis tool can supply various significant information such as statistical distribution including personal/environmental exposure level, daily time activity pattern and individual susceptibility. Further research is needed for investigating real data of these input variables and personal exposure concentration and application of this study methodology.