체적함수비 및 주파수에 따른 풍화토의 전기비저항 특성

손영환,봉태호,장병욱,Son, Young-Hwan,Bong, Tae-Ho,Chang, Pyoung-Wuck 한국농공학회 2008 한국농공학회논문집 Vol.50 No.5

This study was conducted to define a characteristics of Electrical Resistivity of weathered soil against volumetric water content and frequency. It is essential to analyze and understand a characteristics of the Electrical Resistivity for evaluation of soil as subsurface contaminant detection. Before the test, an effect of pore water and ion were checked using four liquids(distilled water, tap water, potassium chloride 1.8mM, and 3.7mM). As a result, the correlation between the volumetric water content and the Electrical Resistivity was estimated. The Electrical Resistivity decreases with increasing frequency and water content. Also, Electrical Resistivity could be described by an exponential function of volumetric water content with the constants.

재활용 도로재료의 회복탄성계수 산정을 위한 적용 모델의 평가

손영환,Son, Young-Hwan 한국농공학회 2010 한국농공학회논문집 Vol.52 No.2

Many models have been used to represent the effects of confining stress, bulk stress, and shear stress on the value of the resilient modulus (Mr). This study was conducted to estimate Mr of the recycled materials such as recycled concrete aggregate (RCA) and recycled asphalt pavement (RAP) through the repeated load cyclic test. Also, two models were applied to estimation of Mr for comparing between measured Mr values and predicted Mr values. The first model (A-model) can provide a quick and easy estimation of the Mr based on the bulk stress, while the second model (N-model) includes not only the bulk stress but also the shear stress. Statistical analysis indicated that all results using the both of models are significant at a 95 % confidence level. Therefore, the both of models could be used as an effective prediction model of Mr for RCA and RAP. Especially, the Model 2 including the parameters of the bulk stress and the shear stress could give more reliable estimation at the high range of Mr values.

CKD 혼합에 따른 Recycled Material의 회복탄성계수와 일축압축강도 특성

손영환,Son, Young-Hwan 한국농공학회 2010 한국농공학회논문집 Vol.52 No.2

This study was conducted to determine the resilient modulus (Mr) and the unconfined compressive strength (UCS) of two recycled roadway materials such as recycled pavement material (RPM) and road surface gravel (RSG) with or without cement kiln dust (CKD). The recycled materials were blended with two CKD contents (5, 10 %) and 28 day curing time. Mr and UCS tests were also conducted after 10cycles of freezing and thawing to asses the impact of freeze-thaw cycling. Mr was determined conducting by the laboratory test method described by NCHRP 1-28A. Stabilized RPM and RSG had a modulus and a strength higher than unstabilized RPM and RSG. Mr and UCS of RPM and RSG mixed with CKD increased with increasing CKD content. The results indicated that the addition of CKD could be improved the strength and the stiffness of RPM and RSG. Therefore, RPM, RSG and CKD could be used as an effective materials in the reconstruction of roads.

Fall Cone을 이용한 풍화도 측정(실트질 모래에 대하여)

손영환,김성필,장병욱,Son, Young-Hwan,Kim, Seong-Pil,Chang, Pyoung-Wuck 한국농공학회 2008 한국농공학회논문집 Vol.50 No.1

It is essential to analyze and classify the physical characteristics of weathered granite for engineering purposes. This paper is to suggest a physical method to determine the degree of weathering of weathered soils. A new classification method for determining the degree of weathering is suggested, based upon the results from laboratory tests including fall cone test. According to the proposed physical method using fall cone apparatus, the measured values of the samples from the same area show distinctive difference of weathering. The water content tends to increase with increasing the degree of weathering at the same penetration in fall cone test. And relationship between CWI and water content are expressed one equation in Hwaseong area and Ilsan area.

풍화토층의 구분을 위한 시험법의 적용

손영환,노수각,김성필,장병욱,Son, Young-Hwan,Noh, Soo-Kack,Kim, Seong-Pil,Chang, Pyoung-Wuck 한국농공학회 2009 한국농공학회논문집 Vol.51 No.3

The undisturbed specimens used in this research were sampled in the field by the sequential sampling method. In addition, four testing methods were applied to identify for the characteristics and classification of weathered strata. N-value by standard penetration test was obtained from in the field and then analyzed using normalization method. Other methods such as X-ray grain size distribution, X-ray fluorescence spectroscopy(XRF), and fall cone test were carried out in the lab. These analyzed results indicate that distribution of particle, composition of minerals are changed in accordance with the degree of weathering, unusual strata and depth. Consequently, the weathered strata can be extensively separated into two parts according to the test results and each part was shown different in the strata characteristics. It can be prospected that mechanical characteristics should be different, even though mechanical tests were not applied. Furthermore, these results not only make up for the error by one testing method but also contribute more effectively and economically to the design and the construction.

수은과 비소로 오염된 시료의 측정주파수와 농도 변화에 따른 전기적 특성

손영환,봉태호,장병욱,Son, Young-Hwan,Bong, Tae-Ho,Chang, Pyoung-Wuck 한국농공학회 2008 한국농공학회논문집 Vol.50 No.6

In general, ground pollution can be classified with soil pollution and underground water pollution. And ground pollution contaminates the land with garbage dumps and other harmful waste products as heavy metals that can also eventually enter our water supply. This study was conducted to define a characteristics of the electrical resistivity and the permittivity of weathered soil that was contaminated with heavy metals as Mercury and Arsenic. It is not easy whether contamination of soil as subsurface contamination is decided or not and at an early stage especially do that. Therefore the electrical resistivity and the permittivity were used to make up for this defects. These methods are more economical and more effective than the existing methods. And variation of the electrical resistivity and the permittivity values were found against the change of concentration of Mercury and Arsenic aqueous solutions and measuring frequency. These analyzed results indicate that the electrical resistivity and the permittivity tend to decrease against increasing measuring frequency. The electrical resistivity and the permittivity are also found to show the function of frequency.

아연으로 오염된 시료의 전기적 특성

손영환 ( Son Young Hwan ),김성필 ( Kim Seong Pil ),허준 ( Heo Joon ),장병욱 ( Chang Pyoung Wuck ) 한국농공학회 2007 한국농공학회 학술대회초록집 Vol.2007 No.-

Ground pollution is usually meaned soil and underground water pollution. This study was conducted to define a characteristics of electrical resistivity(ER) and a permittivity of weathered soil that was contaminated with a zinc solution. It is not easy whether contamination of soil as subsurface contamination is decided or not and at an early stage especially. Therefore the ER and the permittivity were used to make up for this defects. These methods are more economical and more effective than the existing methods. And variation of the ER and the permittivity values were found against the change of the concentration of the zinc solution and a frequency. As a result, the ER and the permittivity tend to decrease with increasing the concentration of the zinc solution and the frequency.

CA 그룹웨어 연동형 디바이스 ID 기반 하이브리드 공인인증 보안 기법

손영환(Young-Hwan Son),구경옥(Kyung-Ok Koo) 한국엔터테인먼트산업학회 2009 한국엔터테인먼트산업학회 학술대회 논문집 Vol.3 No.2

본 논문에서는 사용자의 편의성 향상과 안전한 사용자 인증의 초석인 인증서의 원천지 무결성을 보장하기 위한 방안으로써, PKI 공인인증서 인증기법에 디바이스 ID에 기반한 하이브리드 공인인증 기법을 제안하여 기존 하이브리드 PKI 공인인증서 인증기법에서의 사용자 편의성과 인증 기법의 보안성을 향상시키고자 한다.

보육사업의 재정실태와 개선방안 -전국 대비 부산시 보육사업을 중점으로-

손영환(Young Hwan Son) 한국지방교육경영학회 1998 지방교육경영 Vol.3 No.2

디바이스 ID 기반의 하이브리드 PKI 공인 인증 보안 기법

손영환(Young-Hwan Son),최운수(Woon-Soo Choi),김기현(Ki-Hyun Kim),최한나(Han-Na Choi),이대윤(Dae-Yoon Lee),오충식(Chung-Shick Oh),조용환(Yong-Hwan Cho) 한국컴퓨터정보학회 2010 韓國컴퓨터情報學會論文誌 Vol.15 No.5

본 논문에서는 안전한 사용자 인증의 초석인 인증서의 원천지 무결성 보장과 함께 사용자의 편의성 향상을 위한 방안으로써, PKI 인증서 인증기법에 디바이스 ID에 기반한 하이브리드 공인 인증 기법을 제안하여 기존 하이브리드 PKI 공인인증서 인증기법에서의 사용자 편의성과 보안성을 향상시키고자 한다. 본 논문에서 제안하는 모델의 특징은 크게 다섯 가지로 설명할 수 있다. 첫째, 사용자 스스로 각각의 인증 상황 및 보안 수준에 맞는 정책을 선택 할 수 있어 사용자의 편의성을 향상 시킬 수 있다. 둘째, 정책별 디바이스 ID의 해시 값인 DLDI Key(Device Location Dependence ID Key)의 비교를 통해 사용자 인증서의 원천지 무결성을 보장할 수 있다. 셋째, EOTP Key(Event of One Time Password Key)를 통해서 인증서를 암호화, 복호화 하는 키의 값을 매 인증 시도마다 변경시킴으로써 보안성을 향상 시킬 수 있다. 넷째, 인증서에 Index 값을 추가시켜 멀티 디바이스에 인증서의 저장이 가능하다. 다섯째, 보안 카드 등 인증서의 원천지 무결성 보장을 위한 추가적인 장치가 필요치 않아, 인증 처리 시간의 지연을 단축시킬 수 있으며 인증 서버의 연산 부하를 감소시킬 수 있다. In this study, the hybrid authorization quotation technique is based on the device ID for the integrity of the source region guarantee of user certificate, in order to improve the convenience and security for user in the hybrid PKI certificate Mechanism for authentication. The feature of the model in which it is presented from this paper is 5. First, because the user can select the policy himself in which it matches with each authentication situation and security level, the convenience can be improved. Second, the integrity of the source region of the user certificate can be guaranteed through the comparison of the DLDI Key, that is the hash-value of the device ID. Third, the security can be improved by continuously changing an encoding, and the value of the key in which it decodes through the EOTP Key. Fourth, the index value is added to a certificate, and the storage of a certificate is possible at the Multi-Device. Fifth, since the addi the inan aratus for the integrity of the source region guarantee of a certificate is not needed, the authentication process time can be reduced and the computational load of the certificate server can be reduced also.