• 한국지반신소재학회논문집
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• 제12권2호
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• pp.67-74
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• 2013

본 연구에서는 의사결정나무모형을 적용하여 개발된 급경사지재해 예측프로그램 SHAPP ver 1.0을 이용하여 강원도 횡성군 우천면 하대리 일대 영동고속도로 주변에 대한 급경사지재해 예측을 실시하였다. 이를 위하여 먼저 대상지역의 총 10개소에서 토층시료를 채취하고, 이에 대한 토질시험을 실시하였다. 대상지역에 대한 토질시험결과를 토대로 투수계수와 간극비에 대한 주제도를 작성하고 수치지형도를 이용하여 지형의 경사분석을 실시하였다. 이를 이용하여 급경사지재해 예측을 실시한 결과 총 27,776개의 해석셀 가운데 2,120개의 셀에서 급경사지재해가 발생될 것으로 예측되었다. 이때 해석셀의 크기는 $5m{\times}5m$이므로 급경사지재해 발생예상 면적은 $53,000m^2$으로 나타났다.

• 대한토목학회논문집
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• 제30권6C호
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• pp.219-229
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• 2010

우리 나라는 산지가 국토 면적의 약 70%를 차지하고 있기 때문에 장마나 태풍 시 집중 강우에 의하여 다수의 사면 붕괴가 발생하고 있으며, 이러한 사면 붕괴로 인해 많은 인명과 재산피해가 발생되고 있다. 이러한 상황하에서 사면 붕괴로 인한 피해를 경감시키기 위해서는 광범위한 지역에 걸쳐 분포되어 있는 사면을 대상으로 붕괴가 예상되는 위험한 사면부를 추출하여 방재 대책을 강구할 필요성이 있으며, 이를 위해서는 사면의 안정성 또는 위험도의 정량적 평가가 선행되어야 한다. 그러나 국내에는 아직까지 광역의 수많은 사면을 대상으로 강우와 지형적 요인 및 토질공학적 요인을 고려한 위험도 예측모델이 구축되어 있지 않은 실정이다. 따라서, 본 연구에서는 유역 내 지하수위의 시간 변화를 구하는 집수모델과 무한사면의 안정해석모델을 조합한 해석기법을 제안하고, 이를 이용한 해석 사례를 소개하고자 한다.

• 유통과학연구
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• 제13권5호
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• pp.53-60
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• 2015

Purpose - The purpose of this paper is to shed light on the importance of the slope and curvature of the volatility curve implied in option prices in the KOSPI 200 options index. A number of studies examine the implied volatility curve, however, these usually focus on cross-sectional characteristics such as the volatility smile. Contrary to previous studies, we focus on time-series characteristics; we investigate correlation dynamics among slope, curvature, and level of the implied volatility curve to capture market information embodied therein. Our study may provide useful implications for investors to utilize current market expectations in managing portfolios dynamically and efficiently. Research design, data, and methodology - For our empirical purpose, we gathered daily KOSPI200 index option prices executed at 2:50 pm in the Korean Exchange distribution market during the period of January 2, 2004 and January 31, 2012. In order to measure slope and curvature of the volatility curve, we use approximated delta distance; the slope is defined as the difference of implied volatilities between 15 delta call options and 15 delta put options; the curvature is defined as the difference between out-of-the-money (OTM) options and at-the-money (ATM) options. We use generalized method of moments (GMM) and the seemingly unrelated regression (SUR) method to verify correlations among level, slope, and curvature of the implied volatility curve with statistical support. Results - We find that slope as well as curvature is positively correlated with volatility level, implying that put option prices increase in a downward market. Further, we find that curvature and slope are positively correlated; however, the relation is weakened at deep moneyness. The results lead us to examine whether slope decreases monotonically as the delta increases, and it is verified with statistical significance that the deeper the moneyness, the lower the slope. It enables us to infer that when volatility surges above a certain level due to any tail risk, investors would rather take long positions in OTM call options, expecting market recovery in the near future. Conclusions - Our results are the evidence of the investor's increasing hedging demand for put options when downside market risks are expected. Adding to this, the slope and curvature of the volatility curve may provide important information regarding the timing of market recovery from a nosedive. For financial product distributors, using the dynamic relation among the three key indicators of the implied volatility curve might be helpful in enhancing profit and gaining trust and loyalty. However, it should be noted that our implications are limited since we do not provide rigorous evidence for the predictability power of volatility curves. Meaning, we need to verify whether the slope and curvature of the volatility curve have statistical significance in predicting the market trough. As one of the verifications, for instance, the performance of trading strategy based on information of slope and curvature could be tested. We reserve this for the future research.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.191-195
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• 2007

Recently, landslides frequently happen at a natural slope during period of intensive rainfall. With rapidly increasing population of steep terrain in Korea, landslides have become one of the most significant natural hazards. Thus, it is necessary to protect people from landslides and to minimize the damage of houses, roads and other facilities. To accomplish this goal, many landslide prediction methods have been developed in the world. In this study, a simple landslide prediction system that enables people to escape the endangered area is developed. The system is focused to debris flows which happen frequently during periods of intensive rainfall at steep slopes in Kangwondo. This system is based on the wireless sensor network that is composed of sensor nodes, gateway, and server system. Sensor nodes that are composed of sensing part and communication part are newly developed to detect sensitive ground movement. Sensing part is designed to measure tilt angle and acceleration accurately, and communication part is deployed with Bluetooth (IEEE 802.15. I) module to transmit the data to the gateway. To verify the feasibility of this landslide prediction system, a series of laboratory tests is performed at a small-scale earth slope supplying rainfall by artificial rainfall dropping device. It is found that sensing nodes installed at slope can detect the ground motion when the slope failure starts. It is expected that the landslide prediction system by wireless senor network can provide early warnings when landslides such as debris flow occurs, and can be applied to ubiquitous computing city (U-City) that is characterized by disaster free.

• 화약ㆍ발파
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• 제26권2호
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• pp.38-44
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• 2008

최근에 국내의 도로건설계획은 기존도로의 선형을 개량하거나 변경하는 데에 중점을 두므로, 건설하고자 하는 도로는 보다 현재 직선화되고 있는 추세이다. 국내의 지형은 대부분 산악지로 구성되어 있어 도로선형의 직선화에 따라 많은 교량과 터널의 계획이 불가피하며, 일부 산악터널의 갱구부는 터널굴착시 작업공간이 협소한 가파른 지형을 갖는 산안 계곡에 위치하는 경우가 있다. 이와 같이 가파른 지형에 터널 갱구부 굴착시 대안으로 역방향 굴착을 들 수 있는데, 3가지의 중요한 고려사항이 있다. 첫째, 적정한 폭, 높이, 그리고 길이로 Pilot 터널을 계획하는 것이며, 둘째, 터널 갱구부의 편토압에 대한 영향을 평가하는 것이고, 셋째, 갱구부의 얕은 심도의 지반조건에 대한 터널 안전성을 확보하는 것이라고 할 수 있다. 따라서 본 연구는 3차원 수치해석에 의해 얻어진 결과를 토대로 역방향 굴착의 적정성 및 Pilot 터널의 적용 범위를 제안코자 한다. 해석결과 Pilot 터널은 터널 안쪽 $20{\sim}25m$ 지점 전부터 갱구부 쪽으로 굴착하는 것이 적정함을 보이고 있다.

• Journal of Welding and Joining
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• 제34권6호
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• pp.62-68
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• 2016

Laser welding has superior characteristic such as low distortion, high welding speed, easy automation and real time control. But it is easy to occur weld defects such as porosity, crater, humping bead in the area of welding start and end. These weld defects can be suppressed by applying the wave shape control. In this study CW fiber laser was used for welding of $0.5mm^t$ pure titanium. Penetration properties were evaluated with the time of slope up and down. After then the bead shape was observed, and the maximum depth and the area of crater were measured. The bead shape of welding start area changed to be sharp with increase of slope up time and non-weld area of welding start increased. The crater and humping bead were suppressed with slope down time. The cooling rate of crater area was understood through measure of the hardness. Also, The distribution tendency of alloying elements was observed by EPMA and EDS. When wave shape control didn't applied to weld, the hardness of end weld increased due to rapid cooling rate and the hardness of rear part in the crater was higher than that of fore part. On the other hand, when the wave shape control was used for end weld, the increase of hardness in the end weld couldn't be found due to gradual cooling rate.

• 멤브레인
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• 제21권4호
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• pp.329-335
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• 2011

당뇨병 환자의 혈당치 측정을 위하여 메톡시에톡시기와 트라이플루오르에톡시기가 함께 치환된 포스파젠 고분자를 기초로 한 새로운 형태의 진단막을 제조하였다. 플라즈마와 혈액속의 글루코우즈의 농도를 변화시켜가며 활성화 된 폴리포스파젠 진단막을 가지고 680 nm에서의 최종흡광도를 측정하였다. 시간에 따른 흡광도 변화량(K/S)의 최종 결과치가 글루코우즈의 농도가 증가함에 따라 직선적으로 증가하였다. 친수성기와 소수성기의 치환율이 글루코우즈의 농도 측정에 미치는 영향을 조사하였다. 친수성기의 치환율이 증가함에 따라 글루코우즈의 농도와 K/S와의 기울기 값(Dose-Response Slope : DRS)이 점차 증가하였다. 그러나 친수성기의 치환율이 30% 이상일 경우에는 DRS가 급격히 증가하여 정확한 글루코우즈의 농도 측정이 어려웠다.

• 산업기술연구
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• 제22권A호
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• pp.153-159
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• 2002

This paper is an experimental work of estimating friction angle of very coarse grained soil such as rubble mound by performing laboratory experiments. Two crushed rocks of rubble mound were used for tests. Triaxial compression tests with drained conditions were performed to measure friction angles of soils prepared by mixing the crushed soil having an identical coefficient of uniformity with different maximum grain size distribution. Centrifuge model experiments with those soils were also performed to measure angle of repose and to estimate friction angle of soil from measuring the slope of slip line in the active stress state. Model tests were carried out by changing the G-levels of 1G and 50G. From triaxial compression tests, the measured value of friction angle of soil is in the range of $41{\sim}57^{\circ}$. The measured value of repose angle is in the range of $32{\sim}35^{\circ}$. The values of friction angle are found not so sensitive to the maximum grain size of soil as long as the coefficient of uniformity is identical. Estimated value of friction angle from measuring the slope of slip line in the active stress state is in the range of $30{\sim}46^{\circ}$. Thus, the estimated angle of friction are found to be greater in the order of the measured angle of repose, the estimated value from the slope of active state, and triaxial compression test results. On the other hand, the measured values of friction angle from triaxial tests were compared with empirical equations, based on the relation between friction angle and void ratio. Equations proposed by Helenelund(l966) and Hansen(1967) found to be relatively reliable to estimate friction angles of soil.

• 한국방재학회 논문집
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• 제10권6호
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• pp.45-52
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• 2010

사면붕괴로 인한 피해를 최소화하기 위한 방법 중 하나는 사면의 변위발생을 계측하고 붕괴를 예측하여 사전에 방재대책을 수립하는 것이다. 이를 위해 다양한 계측장비들을 활용하여 붕괴를 예측할 수 있는 기술들이 개발되고 있다. 특히 최근에는 사면의 변위발생을 계측하기 위해 첨단 촬영 장비인 지상라이다를 활용하려는 노력이 시도되고 있다. 지상 LiDAR는 수백 미터의 거리에서도 수 mm의 정확도로 대상물의 3차원 정보를 획득 할 수 있기 때문에 문화재 복원, 3차원 모델링, 지형도 작성 등 다양한 분야에서 활용되고 있으며 최근에는 구조물의 변위계측에도 활용되고 있다. 본 연구에서는 이러한 지상라이다를 이용하여 붕괴위험이 높은 위험관리사면을 대상으로 변위 모니터링 수행하였다. 그 결과 지상라이다의 현장적용 가능성을 확인할 수 있었으며 모니터링 방법에 대해 제시할 수 있었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1543-1546
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• 2005

This paper presents a method to measure a large surface shape using atomic force microscopy, which has been used mostly for measuring over very tiny surfaces. Experiments are performed to measure a step height and a slope of a test sample. The proposed method is rigorously compared with the coordinate measuring machine. The repetition accuracy and the effects of the set point are also studied. The experimental results show that the proposed method is reliable and should be effective to measure both the nano-accuracy surface profile as well as the micro-accuracy global shape of a macro/micro parts using atomic force microscope.