• Clean Technology
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• v.24 no.3
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• pp.157-165
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• 2018

In this study, the removal of $Si_3N_4$ particles from the surface of a silicon wafer was investigated by using supercritical carbon dioxide, the IPA co-solvent and cleaning additive chemicals. First, the solubility of several surfactants and binders in supercritical carbon dioxide solubility and particle dispersibility in the binders were evaluated in order to confirm their suitability for the supercritical cleaning process. Particle removal experiments were carried out with adjusting various process parameters and reaction conditions. The surfactants used in the experiment showed little particle removal effect, producing secondary contamination on the surface of wafers. On the other hand, 5 wt% (with respect to $scCO_2$) of the cleaning additive mixture of trimethyl phosphate, IPA, and trace HF resulted in 85% of particle removal efficiency after $scCO_2$ flowing for 4 minutes at $50^{\circ}C$, 2000 psi, and the flow rate of $15mL\;min^{-1}$.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.23-36
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• 2013

PURPOSES: The problem under this circumstance is that the erosion not only drops strength of the steel dowel bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem, alternative dowers bars are developed. METHODS: In this study, the bearing stresses between the FRP tube dowel bar and concrete slab are calculated and compared with its allowable bearing stress to check its structural stability in the concrete pavement. These comparisons are conducted with several cross-sections of FRP tube dowel bars. Comprehensive laboratory tests including the shear load-deflection test on a full-scale specimen and the full-scale accelerated joint concrete pavement test are conducted and the results were compared with those from the steel dowel bar. RESULTS: In all cross-sections of FRP tube dowel bars, computed bearing stresses between the FRP tube dowel bar and concrete slab are less than their allowable stress levels. The pultrusion FRP-tube dowel bar show better performance on direct shear tests on full-scale specimen and static compression tests at full-scale concrete pavement joints than prepreg and filament-winding FRP-tube dowel bar. CONCLUSIONS: The FRP tube dowel bars as alternative dowel bar are invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Also, the pultrusion FRP-tube dowel bar performed very well on the laboratory evaluation.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.55-55
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• 2011

기후변화는 지구 온난화와 같은 인위적인 변화와 기후 자체의 자연적인 변동성에 기인하고 있으며 기후변화의 영향으로 인해 물관리 분야에도 영향을 받고 있다. 이러한 기후변화의 영향은 가용 수자원량의 예측과 이를 관리하는 측면의 불확실성을 증가 시키고 있으며 미래 물관리가 더욱 어려울 것으로 전망되고 있다. 이에 본 연구에서는 기후변화에 대응한 수자원의 종합적인 관리 차원에서 시공간적 물수급 불균형 해소를 위한 방법론을 제시하고자 유역 물관리 모형인 KModSim을 이용하여 낙동강유역을 대상으로 수자원 네트워크를 구축하였다. 유역의 자연유량을 산정하기 위하여 SWAT 모형을 이용하였으며, 현실적으로 유역의 물관리 문제에 접근하기 위해서 낙동강 유역의 수리시설물, 생 공용수 및 농업용수, 댐용수 및 하천수 점용허가 등의 수리권 자료에 근거하여 KModSim을 구축하였다. 미래 기후변화 시나리오(온실가스 배출이 현 수준에서 지속될 것으로 가정한 균형적 발전 시나리오인 A1B 사용)를 적용하였으며 현재(1980~2009년)와 미래(2011~2100년)를 각각 30년씩 구분하여 기후변화에 대한 생활 공업 농업용수의 수요량 변화, 하천유지용수의 공급 변화, 다목적 댐 모의 운영 결과를 검토하였다. 낙동강 유역의 상류 다목적댐의 용수공급 능력은 2040년 초반부터 저류량이 감소 등 물공급에 심한 영향을 받을 것으로 전망되었다. 이와 같은 기후변화의 영향은 수요량에 대응하는 저수지의 공급능력에 영향을 주게 되어 물공급 시설의 운영에 어려움이 있을 것으로 전망되었다. 농업용수에 대한 기후변화의 영향평가 결과 또한 2041년부터 2070년의 기간에 부족이 발생하는 것으로 모의되었다. 생활과 공업용수의 물공급은 기존의 물공급 시설 투자 덕분으로 기후변화의 영향이 두드러지지 않은 것으로 나타났으나 일부 지역은 기후변화에 영향을 고려하지 않더라도 취약한 것으로 모의 되었다. 하천유지유량의 경우 지류가 본류에 비해 하천유지유량의 확보가 어려운 것으로 나타났지만 양적으로는 본류가 부족량이 더 많은 것으로 모의되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.79-79
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• 2020

기존과 현행 수자원 관련 의사결정은 법, 정책 및 규정의 틀에서 이루어진다. 그러나 우리나라에서 재현되고 있는 물의 사회적 현안과 갈등들을 생각할 때 이들 의사결정을 위한 틀이 충분한 역할을 하고 있는가에 의문을 제시하고 다른 길을 모색할 필요가 있다. 본 논문은 물 의사결정과 행동을 주도하기 위한 기존 틀의 보완책 또는 새로운 대안으로 섬진강 유역의 수자원 이용 사례를 통하여 물 윤리의 도입과 제도화를 제안한다. 물 윤리(water ethics)는 물 정책, 관리 및 실무 등 실제행동의 복잡한 환경에서 우리의 가치를 적용하기 위해 채택하는 원칙이다. 대부분 물 윤리적 행동선택은 여러 개의 상충되는 가치를 포함하고 있어 원칙이 필요하며, 존중할 가치와 무시할 가치를 선택해야한다. 또한 이러한 가치 결정을 신속하고 효율적으로 수행하여 물 갈등해소를 지원할 필요가 있다. 물 윤리의 가치 영역은 환경, 사회, 경제, 문화, 거버넌스 등 5개로 분류할 수 있다. 섬진강 유역에는 1960년 이후 경제발전을 위하여 섬진강댐, 주암댐, 보성강댐, 동복댐, 동화댐 등 6개의 댐이 건설되었고, 이들 댐에서 확보한 수량의 60%는 섬진강 유역 외의 생·공용수, 농업용수 및 발전용수로 도수되고 있다. 송정지점을 기준으로 연평균 유출량은 댐건설 전·후에 40%로 감소한 것으로 추정되었다. 물 윤리 차원에서 이들 정책은 1960년 정부가 추구했던 경제 가치에 최우선하는 물 관리라고 할 수 있다. 이러한 물 관리는 하류로 흘러가는 수량의 부족을 초래하여 하구 생태계 훼손을 초래하였다. 특히 하구 기수역에서 상류 유입량 감소로 인한 염수의 유입으로 재첩의 생태환경이 악화되어 전통적인 재첩채취 어업문화를 이루어 왔던 어민들이 고충을 겪고 있다. 물 윤리 차원에서 섬진강의 물 관리는 경제와 함께 환경, 사회, 문화 및 거버넌스 가치의 비중을 높일 필요가 있다. 또한 하구의 환경생태 가치 보전에 필요한 환경유량을 확보하기 위해 공업용수와 농업용수 이용 효율성(재이용, 절약, 경제성), 생활용수의 수요관리, 공급시설의 최적 운영 전략을 물 윤리적 차원에서 평가해야한다. 최종적으로 확보된 환경유량의 효과적 활용을 위하여 그동안 물 관리에서 소외되었던 어민을 포한한 지자체, 수공·농어촌공사·한수원 물 관리기관, 중앙정부 등 이해관계기관의 거버넌스 가치를 높여야한다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.5
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• pp.717-733
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• 2019

In this study, lining thickness distribution and its behind state (particularly, its void state) were analyzed using the GPR survey data performed on three currently operating NATM tunnels. Results of GPR analysis showed that void areas were mostly detected between concrete lining and primary support, particularly, near the crown of the tunnels. The lining thickness in the left-hand side of the tunnel was different from that of the right-hand side by 8.6~253.5 mm when measured in transverse direction. It was also found that longitudinal cracks were prevailed in the area lining thickness was sharply changed. Longitudinal thickness distribution at the crown was also studied and tested by performing 3 goodness-of-fit tests in order to find the most suitable thickness distribution. Normal distribution (or similar distribution) fit most suitably to the measured data if the measured average thickness was larger than designed one; Gamma and/or Inverse Gauss distribution fit to the measured data reasonably well if the measured average thickness was less than the designed value of thickness. Since actual lining thickness can be a potential index when assessing the state and safety of the unreinforced NATM tunnel lining, measuring of the lining thickness with GPR survey might be needed rather than assuming the thickness is always constant and same with the designed value.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.36 no.6
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• pp.1101-1107
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• 2016

As an increase in the amount of RAP, there are growing interests in recycling asphalt concrete. In case of using the RAP as recycled asphalt pavement, it tends to be quality deteriorate. Therefore, the amount of RAP using is advised to be limited or has to be used with rejuvenator. In this study, asphalt mixture containing WMRA was analyzed to be used up to 50% for the sake of convenience on the process. As the results of evaluation, there was no significant difference in case of using 30% of RAP in the test of Marshall stability. However, in case of WMRA using up to 50%, it was satisfied criteria by flow value at 34.7. Further, result of toughness test was found that the crack resistance showed 55% higher than using straight asphalt when using WMRA binder up to 50%. According to the results of directly comparing crack resistance through repeated direct tensile test, it was shown that the fatigue crack resistance of WMRA pavement was increased by 263%. Therefore, it was shown that WMRA binder was effective in recycling RAP because WMRA binder could increase the percentage of RAP using up to 50%.

• Journal of Animal Science and Technology
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• v.50 no.5
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• pp.581-590
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• 2008

Growth curves for ultrasonic carcass traits such as longissimus muscle area, backfat thickness and marbling score as well as chest girth which was simultaneously measured when carcass traits were investigated using ultrasound measuring technique were estimated to identify growth patterns and to adjust maturing effects in order to evaluating genetic merits on cows in farming basis. 27,410 records from 22,451 cows on which of 15~90 month of age were investigated from the national wide of Korea using by ultrasonic scanning techniques by the skilled persons from 2002 to 2007. Van Bertalanffy growth function was applied for estimating growth curves on these traits. Carcass traits and chest girth would be linearly increased by body condition score. It might be used for multiplicative correction factors for pre- adjustment on the body condition scores. Growth pattern on chest girth would be quickly reached to mature size and stable on after reached to asymptotic mature size. Longissimus muscle area would also be reached to mature size but little smoother than chest girth. Otherwise, growth curve on backfat thickness would be steadily increasing up to 7 years of age. It also showed large individual difference by way of mean square error. Marbling score would be steadily increased but sharper than those on backfat thickness. It would be reached to mature size up at 5 years of age. Those growth curves would be used for correcting function on age at investigating on genetic evaluation system.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.74-79
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• 2020

Safety inspection of cable-supported bridge has increasingly attention as many cable-supported bridges are currently constructed/operated. Whilst cables as a main component in cable-supported bridge should be inspected regularly, traditional method (visual inspection) has limitation to check the condition of cables properly due to restricted factors. It is evidently necessary to develop cable-inspection robot to overcome this concern. In this respect, the main aim in this study is to manufacture the improved robot compared with the existing robot. The improved functions of the robot in this study were that the robot can be operated in large cable diameter (greater than 200 mm) and climbing ability of the robot increases. In addition, electro-magnetic sensor as a non-destructive method in the robot was added to detect damaged cables and performance of the sensor was evaluated in indoor and field experiments. Consequently, the robot was able to move on the cable with ~0.2m/s and to detect damaged cables using the sensor. It was also confirmed that performance of the robot in field test is similar to that in indoor test.

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.135-143
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• 2006

This study evaluated the fatigue resistance characteristics of hot-mix recycled asphalt mixtures which were prepared by a new blending method. Since the binder of RAP shows higher viscosity without being rejuvenated in the ordinary recycled mixture, this new(modified) blending method was developed for obtaining more uniform level of binder viscosity in the recycled mixture. Cold-planned RAP was collected and mix design was performed using 15% RAP content for two virgin aggregate, gneiss and granite. Penetration grade of 60-80 asphalt was used in mixing recycled mixture together with a polymer modifier, LDPE. Indirect tensile fatigue tests were carried out to evaluate characteristics of fatigue resistance of performance of recycled asphalt mixtures. The recycled mixtures with LDPE 6% showed higher repeated loading fatigue life. Fatigue life ratio of new(N) mixing method mixtures was approximately 0.6-0.7 before aging and 0.8-1.0 after aging treatment of ordinary(O) mixing method mixture. This means the N mixture becomes stronger with aging process increase. If further aging is treated, N mixture may be showing stronger resistance than O mixture.

• Journal of the Economic Geographical Society of Korea
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• v.23 no.1
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• pp.71-81
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• 2020

Family companies are the unique industry-academic cooperation-related systems of Korean universities created by universities to promote various forms of industry-academic cooperation with companies. It is important to figure out the current status of family companies in order to understand the achievements of industrial-academic cooperation projects that have been actively pursued since the early 2000s. A lot of studies on industry-academic cooperation have focused mainly on the university's position. On the contrary, this study focuses on understanding the current status of the family company system and the status of industry-academic cooperation. Introduced in 2004, the Family Company System expanded rapidly as it was used as a performance indicator for college financial support projects related to industry-academic cooperation, with 174,425 companies registered as family companies as of 2017. A survey of family companies registered in universities carrying out the LINC+ project shows that companies registered in multiple universities are increasing, with relatively high demand and satisfaction for industry-academic cooperation among companies. Family companies were found to be relatively satisfied in terms of the use of R&D equipment or joint research, while they were relatively less satisfied in terms of workforce training and retraining. While companies have assessed product quality improvements through industry-academic cooperation, they have underestimated the effect of increasing sales and reducing production costs. Further, it was found that it was urgent to expand incentive systems and improve online information services to boost corporate participation in order to enhance the effectiveness of industry-academic cooperation.