• Journal of the Korean Geotechnical Society
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• v.26 no.7
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• pp.17-24
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• 2010

Load Resistance Factor Design method is used increasingly in geotechnical design world widely and resistance factors for drilled shafts are suggested by AASHTO. However, these resistance factors are determined for intact rock conditions; by comparison, most of bedrocks in Korea have weathered condition, so that applying the AASHTO resistance factors is not reasonable. Thus, this study suggests the proper resistance factors for design of drilled shaft in Korea. The 22 cases of pile load test data from 8 sites were chosen and reliability-based approach is used to analyze the data. Reliability analysis was performed by First Order Second Moment Method (FOSM) applying 4 bearing capacity equations. As a result, when the Factor of Safety (FOS) was selected as 3.0, the target reliability indexes (${\beta}_c$) were evaluated as 2.01~2.30. Resistance factors and load factors are determined from optimization based on above results. The resistance factors ranged between 0.48 and 0.56 and load factors for dead load and live load are evaluated as approximately 1.25 and 1.75 respectively. However, when the target reliabilities are considered as 3.0, the resistance factors are evaluated as approximately 50% of the results when the target reliability index was 2.0.

• Applied Chemistry for Engineering
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• v.34 no.3
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• pp.213-220
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• 2023

Mixed-matrix membranes (MMMs), which are composed of a polymer matrix filled with high-performance fillers as a dispersed phase, have been intensively studied for gas separations for the past 30 years. It has been demonstrated that MMMs exhibit superior gas separation performance compared to polymer membranes and are more scalable than polycrystalline membranes. Despite their potential, the commercialization of MMMs has yet to be reported due to several challenging issues. One of the major challenges of MMMs is the non-ideal interface between the continuous polymer phase and dispersed phase, which can result in defect formation (i.e., interfacial voids, etc.). With respect, many MMM studies have focused on addressing the issues through scientific approaches. The engineering approaches for facile and effective large-scale fabrication of MMMs, however, have been relatively underestimated. In this review paper, a novel strategy for fabricating MMMs in a facile and scalable manner using in situ metal-organic framework (MOF) formation is introduced. This new MMM fabrication methodology can effectively address the issues facing current MMMs, likely facilitating the commercialization of MMMs.

• Journal of the Korea Society of Computer and Information
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• v.14 no.2
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• pp.157-168
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• 2009

In this paper, a photovoltaic system is designed with a step up chopper and single phase PWM(Pulse Width Modulation) voltage source inverter. Where proposed Synchronous signal and control signal was processed by one-chip microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical voltage and current dropping character. The single phase PWM voltage source the inverter using inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power for ordinary use. It can cause the effect of saving electric power. from 10 to 20[%]. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. In order to enhance the efficiency of photovoltaic cells, photovoltaic positioning system using sensor and microprocessor was design so that the fixed type of photovoltaic cells and photovoltaic positioning system were compared. In result, photovoltaic positioning system can improved 5% than fixed type of photovoltaic cells. In addition, I connected extra power to the system through operating the system voltage and inverter power in a synchronized way by extracting the system voltage so that the phase of the system and the phase of single-phase inverter of PWM voltage type can be synchronized. And, It controlled in order to provide stable pier to the load and the system through maintaining high lurer factor and low output power of harmonics.

• Environmental and Resource Economics Review
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• v.31 no.1
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• pp.113-139
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• 2022

The iron and steel industry is a manufacturing industry with the largest greenhouse gases emissions and has a great ripple effect on the national economy as a core material industry. This study internationally compared the decoupling patterns of greenhouse gases emissions in the iron and steel industry from 1990 to 2019, focusing on Korea, Japan, and Germany. In particular, unlike previous studies that considered only fuel combustion emissions, this study considered all fuel combustion emissions, industrial process emissions, and indirect emissions from the use of electricity and heat. As a result of the analysis, Korea is interpreted as expansive coupling, Japan as decoupling, and Germany as unclear. Therefore, the decoupling path that the Korean iron and steel industry should take should not be in Germany, but in the form of seeking a decoupling method similar to Japan or more effective than Japan. In addition, this study considered the characteristics of the iron and steel industry as much as possible and presented the causes of the decoupling analysis results and implications for the Korean iron and steel industry through comparison with Japan and Germany. In particular, four factors were suggested as factors which has promoted decoupling in Japan: high value-added of Japanese iron and steel products, development of energy efficiency technology in the Japanese iron and steel industry, strategic M&A of the Japanese iron and steel industry, and maintaining competitiveness according to the closed distribution structure of Japanese iron and steel products. The Korean iron and steel industry should also use the case of Japan as a benchmark to further increase added value through quality uprade and product diversification of iron and steel products, while at the same time making efforts to fundamentally reduce greenhouse gas emissions through the development of new technologies.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.41-57
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• 2022

A workflow is presented to estimate the size of a representative elementary volume and 3-D hydraulic conductivity tensor based on fluid flow analysis for a discrete fracture network (DFN). A case study is considered for a Cretaceous granitic rock mass at Gijang in Busan, Korea. The intensity and size of joints were calibrated using the first invariant of the fracture tensor for the 2-D DFN of the study area. Effective hydraulic apertures were obtained by analyzing the results of field packer tests. The representative elementary volume of the 2-D DFN was determined to be 20 m square by investigating the variations in the directional hydraulic conductivity for blocks of different sizes. The directional hydraulic conductivities calculated from the 2-D DFN exhibited strong anisotropy related to the hydraulic behavior of the study area. The 3-D hydraulic conductivity tensor for the fractured rock mass of the study area was estimated from the directional block conductivities of the 2-D DFN blocks generated for various directions in 3-D. The orientations of the principal components of the 3-D hydraulic conductivity tensor were found to be identical to those of delineated joint sets in the study area.

• Journal of Appropriate Technology
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• v.5 no.2
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• pp.106-113
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• 2019

In order to respond to the global environmental issues, developed countries have been helped the developing countries as the Official Development Assistance (ODA). It is important to understand technology needs of the developing countries to provide the optimum solutions. In this study, the information of the environmental R&D dealing with appropriate technology were comprehensively collected based on the conducted R&D projects from the ministry of environment in Korea. The technology needs by UNFCCC (United Nations Framework Convention on Climate Change) and Korean government were analyzed named as TNA and CPS according to the target developing countries. In South-East Asia and Africa region, there were technology needs on water, biota, air, solid wastes, infrastructures and resources. And they were related to the issues such as environmental pollution, construction, climate change, biodiversity, energy and water management. The technology needs by UNFCCC and Korean government were also compared. Furthermore, the environmental R&D on appropriate technology should be focused on localization and maintenance to provide sustainable solutions to the developing countries.

• Journal of agriculture & life science
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• v.50 no.5
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• pp.205-216
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• 2016

The purpose of this study was to analyze the water quality improvement effect by providing the environmental flows from agricultural reservoir using QUAL2K model. The Bonghyun reservoir, located in Hai-myun, which is in the city of Gosung in the Gyeongnam province, was selected for study area. The stream monitoring was conducted 24 times from 2011 to 2013 and the water quality was monitored in 6 stations including reservoir. Reservoir operation was simulated to determine the environmental flow supply amount from March to October with the constraint that environmental flow supply was restrained when the storage of reservoir was below the one-third of effective storage. The QUAL2K model was selected for water quality simulation. Simulated water quality were compared with the observed for BOD, SS, TN, and TP. R2 were ranged 0.8508~0.9913, RMSE were 0.005~0.52 mg/L, and NSE were 0.949~0.998 for water quality items, respectively. The QUAL2K model simulation results indicated that the water quality improvement effect by providing the environmental flows(3,000 ton/day) were 9.2% for BOD, 21.0% for SS, -9.0% for TN, -2.4% for TP, respectively.

• 한국체육학회지인문사회과학편
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• v.54 no.1
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• pp.535-544
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• 2015

This study was performed to determine the effect of low-intensity resistance training with blood flow restriction (BFR) on muscle volume and strength in elderly women. Sixteen elderly women (70.9±4.6 years) were divided into low (30% 1RM) and high (75% 1RM) intense resistance training groups. Tourniquet cuff (Zimmer, Germany) for BFR was applied only to the right leg during the training period. All subjects performed unilateral leg press, leg extension and leg curl (3 sets×12 repetitions) for 10 weeks (2d/wk). Blood pressure was increased from 110 to 240 mmHg during the training period at the most proximal region of exercised leg. Muscle volume and cross-sectional area (CSA) were measured by MRI and body composition was monitored by dual-energy X-ray absorptiometry (DEXA) and isokinetic muscular strength were analyzed in both legs. The quadriceps CSA (15.2%, p<.001) and muscle volume (13.8%, p<.001) were increased in high-intense trained leg with BFR and the increased rate was highest among groups. The quadriceps CSA (9.8%, p<.001) and muscle volume (6.9%, p<.001) were increased in low-intensity training group with BFR and their increased rates were higher than control groups. The strength by exercise training was significantly improved in all groups and tended to be higher in BFR groups. These results demonstrate low-intensity resistance training with blood flow restriction could be an effective way to improve muscle volume and strength in elderly women.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.638-643
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• 2004

소형화된 기계가공시스템은 사용재료의 다양화와 에너지 및 공간의 감소와 같은 장점을 가지고 작고 정밀한 부품을 가공할 수 있는 시스템으로 주목받고 있다. 이러한 시스템이 비록 그 크기가 일반적인 가공시스템에 비해 작지만 정렬 및 조립공정, 기계요소의 불완정성에 의한 기하학적 오차는 여전히 존재한다. 기하학적 오차 평가는 기계시스템의 정밀도를 효과적으로 적은 비용으로 향상시킬 수 있는 오차보정기술을 적용할 수 있는 토대가 된다. 일반적으로, 3 축의 직선축으로 이루어진 공작기계는 21 개의 오차요소를 가진다. 레이져간섭계는 이러한 오차요소를 평가하는데 널리 사용되고 있지만 광학계를 정렬하고 설치하는 데 많은 어려움이 있으며 한번의 설치로 한 개의 오차요소만이 측정 가능하다. 또한, 소형공작기계의 경우, 그 크기로 인해 기존의 레이져 간섭계를 직접적으로 적용할 수 없다. 따라서, 본 연구에서는 소형공작기계를 포함한 소형가공시스템의 기하학적 오차 평가를 위한 새로운 다자유도 측정시스템을 제안하였다. 5 개의 정전용량변위센서를 사용하는 이 시스템을 통해 한 축의 움직임에 따른 5 개의 오차요소를 동시에 측정 가능하다. 균질 변환행렬을 이용한 측정알고리듬을 구성하고 이를 모의시험을 통해 평가하였다. 수학적 모델링을 통해 각 센서의 출력값을 유도하고 이를 이용하여 각 오차요소를 계산하기 위한 식을 유도하였다. 여기서, 단순화된 식을 적용한 경우, 임의의 오차에 대한 측정 알고리듬의 정확도를 평가하였다. 또한, 측정 시스템의 설치시 발생하는 셋업오차에 대한 측정 알고리듬의 민감도 분석을 행하였다. 제안하는 측정 시스템은 구조가 간단하고 고가의 부가장비가 필요치 않다. 또한, 적은 비용으로 구성할 수 있으며 높은 측정 정밀도를 가지고 소형가공시스템에 필요한 오차 평가를 행할 수 있다.가 함유된 계란을 생산하고 섭취하였을 때 특정항체들의 결합을 통해 병원성 미생물의 성장이나 군체를 형성하는 것을 무력화시켜 결과적으로 병원균을 감소시키거나 억제시킨다는 점이다. 오늘날 약물에 내성을 지닌 박테리아의 출현으로 질병감염을 막는데 항생제의 사용효과가 점차 감소하고 있기 때문에 이러한 항생제를 대체할 수 있는 방안으로 계란항체를 이용할 수 있다.한 중공 플랜지 형상의 단조 방법 중 보다 적절한 단조방법인 압조 단조에 있어서 일반적으로 사용되고 있는 SM10C에 대한 유한요소 해석을 수행하였으며, 제품의 형상비에 따라 폴딩 결함의 발생 유무를 검토하고, 폴딩 결함 없이 단조하기 위한 중공 플랜지의 형상한계 비를 제시하였다.도 경미하게 나타났으나, 경련이 나타난 쥐에서는 KA만을 투여한 흰쥐와 구별되지 않았다. 이상의 APT의 항산화 효과는 KA로 인한 뇌세포 변성 개선에 중요한 인자로 작용할 것으로 사료되나, 보다 명확한 APT의 기전을 검색하고 직접 임상에 응응하기 위하여는 보다 다양한 실험 조건이 보완되어야 찰 것으로 생각된다. 항우울약들의 항혈소판작용은 PKC-기질인 41-43 kD와 20 kD의 인산화를 억제함에 기인되는 것으로 사료된다.다. 것으로 사료된다.다.바와 같이 MCl에서 작은 Dv 값을 갖는데, 이것은 CdCl$_{4}$$^{2-}$ 착이온을 형성하거나 ZnCl$_{4}$$^{2-}$ , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.95-109
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• 2008

We numerically analyzed the nonlinear shoaling, a plunging breaker and its accompanying energetic suspension of sediment at a bed, and a redistribution of suspended sediments by a down rush of preceding waves and the following plunger using SPH with a Gaussian kernel function, Lagrangian Dynamic Smagorinsky model (LDS), Van Rijn's pick up function. In that process, we came to the conclusion that the conventional model for the tractive force at a bottom like a quadratic law can not accurately describe the rapidly accelerating flow over a swash zone, and propose new methodology to accurately estimate the bottom tractive force. Using newly proposed wave model in this study, we can successfully duplicate severely deformed water surface profile, free falling water particles, a queuing splash after the landing of water particles on the free surface and a wave finger due to the structured vortex on a rear side of wave crest (Narayanaswamy and Dalrymple, 2002), a circulation of suspended sediments over a swash zone, net transfer of sediments clouds suspended over a swash zone toward the offshore, which so far have been regarded very difficult features to mimic in the computational fluid mechanics.