국내 점성토 지반의 피에조콘 계수

장인성,이선재,정충기,김명모 한국지반공학회 2001 한국지반공학회논문집 Vol.17 No.6

피에조콘 관입시험(Piezocone Penetration Test, CPTu)으로부터 점성토의 비배수 전단강도를 산정하기 위해서는 피에조콘 계수가 필요하다. 피에조콘 계수는 경험적 방법(기준 시험 방법에 의한 비배수 전단강도와 피에조콘 시험 결과와의 직접 비교에 의하여 결정)에 의해 결정된 값들이 일반적으로 사용된다. 그러나, 경험적인 피에조콘 계수와 관련한 기존의 연구들은 거의 대부분 특정 지역에 대한 값일 뿐 아니라 지반의 공학적 특성이나 지반의 불균질성 등과의 상관관계 분석이 아직까지 미흡하기 때문에 국내 지반에 그대로 적용하기에는 무리가 따를 수 있다. 본 연구에서는 10개 지 역 총 46회의 피에조콘 관입시험 결과를 현장베인시험 및 실내삼축시험으로부터 구한 비배수 전단강도와 비교하여 국내 점성토 지반의 경험적인 피에조콘 계수를 산정하였다. 기존 제시 값들과 비교함과 아울러 그 신뢰성을 분석하고, 소성지수와 과압밀비와의 상관성 및 기준 전단시험 방법에 따른 영향에 대하여 연구하였다. 연구 결과, 다양한 지반 조건에 대하여 얻어진 피에조콘 계수는 평균값을 그대로 적용하기에는 값의 분포 범위가 너무 넓은 것으로 나타났다. 따라서 피에조콘 계수와 밀접한 관련이 있는 것으로 나타난 과압밀비에 따라 구분하여 피에조콘 계수를 적용하는 것이 합리적이며, 이 때 필요한 피에조콘 계수를 제안하였다. In order to evaluate undrained shear strength of clayey soils using Piezocone Penetration Test (CPTu), piezoncone factor is utilized. Commonly, piezoncone factors determined by empirical basis were preferred, which were established by correlation between measurements of piezocone test and undrained strengths obtained from other shearing tests. However, previous studies on the empirical piezocone factors were site-specific and there have been no systematic investigations on the effect of both engineering characteristics of clayey soils and soil non-homogeneity on the piezocone factor. Accordingly, the direct application of the previous results to Korean clayey soils without verification may be inappropriate. In this study, empirical piezocone factors are evaluated by comparing 46 CPTu results of 10 test sites with undrained shear strength obtained from Field Vane Test (FVT) and laboratory triaxial tests. Their reliabilities are investigated by the comparison with the previous piezocone factors and the deviation of data distribution from the mean values. And the effects of referencing test methods and typical engineering characteristics of clayey soils such as overconsolidation ratio (OCR) and plastic Index (I$_{p}$) are examined. Because piezocone factors obtained for various soil conditions are widely distributed, it is not appropriate to use the mean value as a representative. Instead, it is recommended to apply the piezocone factors with OCR, which is found to be a major factor in deriving piezocone factor. The necessitated piezocone factors are presented.d.

파지 디스플레이를 이용한 피부 투과 기능성 펩타이드의 개발

이설훈,강내규,이상화 대한약학회 2013 약학회지 Vol.57 No.2

Biologically active peptides, including growth factors and cytokines, participate in various biological processes in human skin. They could provide a great advantage of maintaining healthy skin. Many peptide growth factors like epi- dermal growth factor (EGF) and human growth hormone (hGH) have been used in cosmetic formulations. The delivery of peptide growth factors across the Stratum corneum, however, seems not sufficient because of their physical properties such as high molecular weight and hydrophilicity. So increasing the penetration of growth factors of interest into skin would be a major concern for ensuring their maximum biological efficacy. In this study, we have identified several skin penetration- enhancing peptides which facilitate delivery of growth factors, when fused at N-terminus of the target protein, into skin. For efficient and rapid screening, we constructed a skin-penetrating assay system using Franz cell and porcine skin. Next, we carried out phage display screening using M-13 bacteriophage with random 12 –amino acid library on its coat protein P3 on that system. After several selection rounds, peptide sequences facilitate the penetration of phages through the porcine skin were identified from a large population of phages. We found that phages with the most potent peptide (S3-2, NGSLNTHLAPIL) could penetrate the porcine skin eight times more than those with control peptide (12 mino acids scram- bled peptide). Furthermore, growth factors conjugated with S3-2 peptide penetrate porcine skin three to five times effi- ciently than non-conjugated growth factors. In conclusion, our data shows that the skin penetration-enhancing peptide we have characterized could increase the delivery of growth factors and is useful for cosmeceutical application.

Evaluation of the Wind Power Penetration Limit and Wind Energy Penetration in the Mongolian Central Power System

Ulam-Orgil, Ch.,Lee, Hye-Won,Kang, Yong-Cheol The Korean Institute of Electrical Engineers 2012 Journal of Electrical Engineering & Technology Vol.7 No.6

This paper describes evaluation results of the wind power penetration limit (WPPL) and the wind energy penetration (WEP) in the Mongolian central power system (MCPS). A wind power plant (WPP) in a power system possesses an output power limit because the power system must maintain a balance between the generation and consumption of electricity at all times in order to achieve an adequate level of quality. The instantaneous penetration limit (IPL) of wind generation at a load is determined as the minimum of the three technical constraints: the minimum output, the ramp rate capability, and the spinning reserve of the conventional generating units. In this paper, a WPPL is defined as the maximum IPL divided by the peak load. A maximal variation rate (VR) of wind power is a major factor in determining the IPL, WPPL, and WEP. This paper analyzes the effects of the maximal VR of wind power on the WPPL, WEP, and capacity factor (CF) in the MCPS. The results indicate that a small VR can facilitate a large amount of wind energy while maintaining a high CF with increased wind power penetration.

전남 광양지역 연약지반의 피에조콘계수 산정

오동춘,김기범,백승철 한국지반환경공학회 2019 한국지반환경공학회논문집 Vol.20 No.2

Using the results from laboratory soil test, field vane test and piezocone penetration test, the engineering characteristics of the soft ground at east side of Gwangyang Port, which is located at south coast of Jeollanam-do, were investigated and optimal piezocone penetration test depth was derived to calculate piezocone factor. In this paper, the results of 61 laboratory soil tests, 226 times of field vane tests and 26 piezocone penetration tests were used. The result of laboratory soil test suggested that some physical properties such as specific gravity, moisture content, liquid limit and plastic index and others are higher than other south coast regions, meanwhile uniaxial compression strength, undrained shear strength, defined as mechanical property, appeared to be relatively small, distributed widely. According to the plastic chart, the ground was classified as high compressibility clay and low compressibility clay, mostly represent to Type 3 clay by Robertson (1990)’s classification chart. Piezocone factor was calculated by empirical method, based on the undrained shear strength which was obtained by the field vane test. According to the analysis with 3 different depth range, to set the appropriate measured depth range of piezocone penetration for comparation, using average value of the range of 5 times the vane length showed the highest correlation. 전남 남해안 지역인 광양항 동측배후단지 연약지반에서 수행한 실내시험, 현장베인시험 및 피에조콘 관입시험 결과를 이용하여 연약지반의 공학적 특성을 규명하고, 피에조콘계수 산정을 위해 최적의 피에조콘 관입시험 심도를 결정하였다. 본 논문에서 이용한 자료는 61개의 실내시험과 226회의 현장베인시험, 피에조콘 관입시험 26개소이다. 실내시험 분석 결과 남해안의 다른 지역에 비해 비중, 함수비, 액성한계 및 소성지수 등의 물리적 특성이 높게 나타나며, 일축압축강도와 비배수전단강도의 역학적 특성은 넓은 범위로 분포하고 비교적 작은 값을 나타냈다. 소성도에 의한 흙 분류 결과 소성이 큰 무기점토(CH)와 소성이 작은 무기점토(CL)로 분류되었으며, Robertson(1990) 분류도표에 의한 흙 분류 결과 대부분 Type 3인 점성토에 해당하였다. 현장베인시험으로 구한 비배수전단강도를 기준으로 경험적 방법에 의해 피에조콘계수를 산정했다. 이를 위해 현장베인시험 측정심도와 비교되는 피에조콘 관입시험의 적정 측정심도 범위를 설정하기 위해 3가지 심도범위로 상관성을 분석한 결과 베인 길이의 5배 범위 측정값의 평균을 사용하는 것이 높은 상관성을 보여준다.

Reliability analysis and evaluation of LRFD resistance factors for CPT-based design of driven piles

Lee, Junhwan,Kim, Minki,Lee, Seung-Hwan Techno-Press 2009 Geomechanics & engineering Vol.1 No.1

There has been growing agreement that geotechnical reliability-based design (RBD) is necessary for establishing more advanced and integrated design system. In this study, resistance factors for LRFD pile design using CPT results were investigated for axially loaded driven piles. In order to address variability in design methodology, different CPT-based methods and load-settlement criteria, popular in practice, were selected and used for evaluation of resistance factors. A total of 32 data sets from 13 test sites were collected from the literature. In order to maintain the statistical consistency of the data sets, the characteristic pile load capacity was introduced in reliability analysis and evaluation of resistance factors. It was found that values of resistance factors considerably differ for different design methods, load-settlement criteria, and load capacity components. For the total resistance, resistance factors for LCPC method were higher than others, while those for Aoki-Velloso's and Philipponnat's methods were in similar ranges. In respect to load-settlement criteria, 0.1B and Chin's criteria produced higher resistance factors than DeBeer's and Davisson's criteria. Resistance factors for the base and shaft resistances were also presented and analyzed.

개착식 굴착공사시 지하수위 저하로 인한 지반상태 탐사 및 해석기법 연구

한유식 한국지반공학회 2018 한국지반공학회논문집 Vol.34 No.11

Precise investigation and interpretation of the ground subsidence risk factors needed to predict and evaluate the settlement problems of the surrounding ground due to the ground excavation. There are various geophysical exploration methods to investigate the ground subsidence risk factors. However, there are factors that influence the characteristics of the underground medium in these geophysical methods, and the actual soil contains complex factors affecting geophysical exploration. Therefore, it is necessary to analyze the effects on the geophysical methods based on the understanding of the geotechnical properties of soil. In this study, a test bed was constructed to consider various complicated factors in the complex ground and the ground behavior was analyzed by numerical analysis. In addition, we analyzed the limitations on investigating the ground subsidence risk factors through ground penetration radar (GPR) survey. As a result, ground subsidence of Open-cut Type Excavation is caused by various factors. Especially, in the case of soft ground condition, it was found that it was greatly influenced by the flow change of groundwater level. At the center frequency of GPR of 250 MHz, the attenuation of the electromagnetic wave is severely attenuated in the clay with high electrical conductivity, making it difficult to penetrate deeply into the ground (4 m below the surface). As the electromagnetic waves pass through the groundwater level below the groundwater, the attenuation of the electromagnetic waves becomes severe.

고혈압성 시상부출혈 환자의 예후에 영향을 미치는 요인

이용재,배학근,이경석,윤일규,이인수 대한신경외과학회 1990 Journal of Korean neurosurgical society Vol.19 No.2

The authors reviewed 114 patients with hypertensive thalamic hemorrhage diagnosed by CT scan, and analysed the factors affecting the prognosis in acute stage of 76 patients who were selected by our criteria. The overall mortality was 26.3%. The isolated hemorrhage within thalamus represented 22.8% and showed 100% survivality of ADL(ability in daily life) 3 or above. The mortality of the other that were extended to internal capsule or midbrain, was 35.7%. The factors affecting poor prognosis were as follows : 1) poor conscious level on admission ; 2) the hematoma on left side in location ; 3) hemorrhagic groups that were extended to internal capsule with intraventricular hemorrhage, midbrain, or both ; 4) the presence of ventricular penetration' or dilatation: 5) the hematoma volume of 10cc or above ; 6) the maximum diameter of 33mm or above : 7) the maximum height of 40mm or above. The prognosis had no significant relationship with the age.

표면균열재의 피로균열 관통거동에 따른 어코스틱에미션

남기우(Ki-Woo Nam),김선진(Seon-Jin Kim),이건찬(Kun-Chan Lee),오정환(Jung-Hwan Oh),오세규(Sae-Kyoo Oh),이주석(Joo-Suk Lee) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.3

Crack penetration behavior by fatigue crack propagation and measurements of AE before-and-after crack penetration were examined using SS41 steel plate. Experimental crack shape of SU type was in good agreement with calculated shape rather than S type. Crack propagation behavior on the front surface appears not to change markedly after penetration. However, crack growth on the back surface appears to accelerate as reported by author. As a crack propagates, AE occurred heavily just before penetration. Then, it decreases and crack is penetrating. A transition from plane strain to plane stress was observed by fractographic study. At this time, separation of fracture surface was shown which affects AE occurrence.

A highly sensitive ultrathin-film iron corrosion sensor encapsulated by an anion exchange membrane embedded in mortar

Im, Healin,Lee, Yunsu,Kim, Do Hyeong,Inturu, Omkaram,Liu, Na,Lee, Sungho,Kwon, Seung-Jun,Lee, Han-Seung,Kim, Sunkook Elsevier BV 2017 Construction and Building Materials Vol.156 No.-

<P><B>Abstract</B></P> <P>In this paper, an embedded ultrathin-film iron (Fe) corrosion sensor passivated with an anion-exchange membrane is developed to reveal the extent of corrosion tendency in reinforced concrete. Rebar in reinforced concrete is mainly corroded due to penetration of chloride ions which are one of the most dominant degradation factor for reinforced concrete. An effective method to monitor the extent of corrosion is to determine the positions where the chloride ions are present beyond the chloride threshold level (CTL). The sensors consist of ultrathin-film iron (Fe) layers deposited on the PET substrate, Au lines as electrode connection lines, and anion exchange membrane encasing the sensor. As the chloride ions exist near Fe layer of sensors, as if rebar has been corroded in reinforced concrete, the macro cells which occur relatively low anode and high cathode with somehow distance between them are made up and pitting corrosion accelerates. The pitting corrosion on the Fe layer of sensor induces the variation of electrical properties, which indicates the corrosion level using variations of resistance (<I>R</I>) and electrical response (<I>R</I>/<I>R<SUB>0</SUB> </I>). To protect the sensor from mechanical and chemical stimuli in a concrete, sensors are encapsulated with an anion exchange membrane that functions not only as a protector, but also as a selector of anions including chloride ions among degradation factors. Therefore, by embedding sensors at every 10 mm depth from the surface of reinforced concrete, we can monitor the corrosion tendency causing penetration of chloride ions with respect to depth. Through the variation of electrical properties in sensors, the velocity of corrosion ( Δ R · R 0 - 1 · <SUP> t - 1 </SUP> ) is suggested as a new parameter, which shows the tendency for corrosion under the surrounding conditions. To confirm the relationship between corrosion velocity as determined by the sensor and the concentration of diffused chloride ions, the chloride concentration in mortar is measured. The developed sensors in this paper are effective to sensitively and accurately monitor the corrosion level of concrete.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Embedding sensors in a fresh mortar. </LI> <LI> Chlorides permeating toward anion exchange membrane of sensors. </LI> <LI> Corroding iron channel by diffused chlorides. </LI> <LI> Occurring rapid variation in electrical changes of sensors by diffused chlorides. </LI> <LI> Indicating corrosion velocities at the spot based on the surrounding condition. </LI> </UL> </P>

자연환기용 공장창호의 빗물유입 저감대책에 관한 실험적 연구

박승욱 ( Cheng Xu Piao ),김태형 ( Tae Hyeung Kim ),하현철 ( Hyun Chul Ha ),허영빈 ( Rong Bin Xu ) 한국산업위생학회 2010 한국산업보건학회지 Vol.20 No.3

Windows are widely used for natural ventilation of the various buildings. Especially high level windows as a part of industrial ventilation systems, play a crucial role in natural ventilation. Compared to mechanical ventilation system, natural ventilation has the advantage of lower installation and operating costs. In general, high level windows for industrial buildings have three types; louver type, 45° open type and 90° open type. Based on previous studies, it was found that the louver type and 45° open type are very effective in reducing rainwater penetration, but they did not have enough ventilation efficiencies. Preliminary tests were performed with the various types of windows. It was found that a 90˚ open double layer type window was the best among those which tested in our preliminary tests. Simulated rain was used to estimate the amount of rain penetrated through windows and to observe the paths of rain penetration. Various 90˚ open windows were tested to find the windows with minimum rain penetration and maximum ventilation efficiency.