• International Journal of Highway Engineering
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• v.13 no.1
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• pp.21-32
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• 2011

The frost penetration depth of pavement is usually estimated from the freezing index that made temperature data analysis of 30 years and decided the thickness of anti-frost layer. The field monitoring region in study was divided into five regions by freezing index 550~650$^{\circ}C{\cdot}$day, 450~550$^{\circ}C{\cdot}$day and 350~450$^{\circ}C{\cdot}$day. Each region has three-section of road pavement such as cutting area, boundary area of cutting and banking, and lower area of banking. The field monitoring system was established both in the section of anti-frost layer and in the section without anti-frost layer. The data analysis was conducted for determination of frost penetration depth within the paved road by the field monitoring system. The result showed that The temperature of subgrade without anti-frost layer shows below zero in centigrade for the region of freezing index 550~650$^{\circ}C{\cdot}$day, up and down around zero degree in subgrade for the region of freezing index 450~550$^{\circ}C{\cdot}$day, and there is no place existed below zero degree in subgrade for the region of freezing index below 450$^{\circ}C{\cdot}$day. With comparison of field frost penetration depth for the cross-sections of pavement, the cutting area shows the greatest frost penetration depth, and less influence of frost penetration depth for the boundary area of cutting and banking, and the least influenced for the lower area of banking.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.25-32
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• 2012

The thickness of anti-freezing layer has been empirically determined using the frost depth obtained from the freezing index and has not been generally considered as a structural layer in pavement design procedure. In fact, the anti-freezing layer makes a role in structural layer and enables to reduce the total thickness of pavement system. The objective of this study is to develop the statistical regression model for evaluating the structural capacity of anti-freezing layer using Falling Weight Deflectormeter(FWD) test data in asphalt pavements. The FWD testing was conducted at the embankment, cutting, and boundary area of various test sections to estimate the structural capacity of anti-freezing layer in different foundation condition. It is observed from this testing that the center deflections of pavement structure with anti-freezing layer are smaller than those without anti-freezing layer ranging from 0.4 to 82.6%. To determine the variables of statistical model, the correlation study has been conducted between various FWD deflection indexes and the anti-freezing layer thickness. It is found that the ${\Delta}BDI$(%)(${\Delta}Basin$ Damage Index(%)) is highly correlated with anti-freezing layer thickness. The ${\Delta}BDI$(%) model were developed for evaluating structural capacity of anti-freezing layer using linear mixed-effect models.

• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.288-296
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• 2003

Generally, application of steel pipe pile as deep foundation member needs special requirement for the connection method between steel pipe pile and concrete footing. Even though two types of connection method are suggested in the related specification, type B-method is provident. To investigate real structural behavior of type B connection, several load tests are done with carefully designed experimental system. The purpose of this experiment is mainly focused on the understanding of actual behavior which can be predicted by design theory. At this research stage, vertical and lateral loading test are done for three types of specimen to review stress concentration, formation and behavior of imaginary RC column in the footing and effect of non-slip device installed in the steel pipe pile. The load resistance mechanism in these specific connection method is predicted based on both experimental results. The three-dimensional finite element modeling is also done for the purpose of comparison between numerical and experimental result. With all the results gained from experiment the structural behavior of imaginary RC column in the design concept is confirmed. The role of non-slip device is very important and it affects the resistance capacity with help of composite action of concrete and steel pipe pile.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.599-604
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• 2020

Since Corona 19, awareness about antibacterial bacteria has changed. Hand washing after going out became a necessity. Also, fogging occurs a lot on the glasses depending on the wearing of the mask. This problem has caused a lot of discomfort in our daily life and changed our perception of antibacterial and anti-fogging. Therefore, in this study, we studied whether mugwort extract is effective in preventing antibacterial and fogging. To obtain the mugwort extract, mugwort was dried, alcohol extracted, and freeze-dried. An antibacterial test was performed using a mixture of mugwort extract, zinc oxide and natural zeolite mixed in 3:7, and a fogging test was performed using mugwort extract and other mixtures. As a result, in the case of E. coli and K. pneumoniae, which were used as test strains in the antibacterial test, the bacteria were not cultured from the medium added with 1% mugwort extract, and the antibacterial activity against representative Gram-negative bacteria was confirmed. In the anti-fog test, a 10 wt% mixture of mugwort extract showed very good results in both the hot and cold parts. We expect the mugwort extract to be effective in antibacterial and anti-fogging, thus helping to overcome Corona 19.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.13-20
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• 2011

There are many mountains in Korean Peninsula, and those used for the construction of roads and railways sectors are forming slopes. Slope collapse occurs with falling rocks and landslide because of the relaxation of the thawing rocks. The heavy rain in summer can also significantly contribute to the process, and abnormal climate change is much more influential than before. Therefore, rockfall-related accidents in rainy season are easily accessible in media every year. There has been a lot of research on application of strengthening compensation of the sections in order to minimize casualties and property damage. Rockfall Protection Net, however, has not been focused on much in the field yet. This study highlights the need of Rockfall Protection Net, since it can segregate the falling rocks inside the net relatively safely. Although there has been a little doubt about the effectiveness of rockfall protection facilities, it is obvious that relevant studies dealing with the solidity of the net are necessary for the rockfall protection net to be capable of supporting rockfall energies. As a result, Expanded metal strength is much more durable compared to the PVC coating net, and it is regarded as an excellent alternative material for the Rockfall Protection Net. In this study, the applicability of Expanded Metal as the alternative of Rockfall Protection Net is verified experimentally.

• Journal of the Society of Disaster Information
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• v.15 no.1
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• pp.98-108
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• 2019

Purpose: The purpose of this study is to test the sprinkler performance to protect the wall and ceiling joints of the sandwich panel warehouse in case of fire. Method: Based on the field surveys, test was setup and combustibles were prepared. The sprinkler discharge tests were performed at the corner of the wall and right under the sprinkler head. Results: It has been found that operation of the K-80 closed sprinkler head prevents the ignition of the sandwich panel and therefore no damage to the joints of sandwich panels. To prevent skipping phenomenon, it is necessary to install the sprinkler head from the corner of the wall and to keep a minimum distance of 2.4m and a maximum distance of 3m. Conclution: A Standard Operation Procedure should be prepared to suppress and rescue of fire brigade for a sandwich panel warehouse protected by perimeter sprinklers preventing a ignition of core materials and control fire.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.3
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• pp.247-255
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• 2010

Bonding strength of shotcrete is a significant influential factor which plays the role of collapse prevention of tunnel crown and of debonding prevention of shotcrete induced by the blasting vibration. Thus, the evaluation of the shotcrete bonding state is one of the core components for shotcrete quality control. In this study, the peak particle velocities induced by blasting were measured on the shotcrete in a tunnel construction site and its effect on the bonding state of shotcrete is investigated. Drilling and blasting technique was used for the excavation of intersection tunnel connecting the main tunnel with the service tunnel. Blast-induced vibrations were monitored at some points of the main tunnel and the service tunnel. The shotcrete bonding state was evaluated by using impact-echo test coupled with the time-frequency domain analysis which is called short-time Fourier transformation. Analysis results of blast-induced vibrations and the time-frequency domain impact-echo signals showed that the blasting condition applied to the excavation of intersection tunnel hardly affects on the tunnel shotcrete bonding state. The general blasting practice in Korea was evaluated to have a minor negative impact on shotcrete quality.

• Electronics and Telecommunications Trends
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• v.20 no.2 s.92
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• pp.93-102
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• 2005

유비쿼터스 코리아(u-Korea) 기본전략에 따르면 우리나라는 정치. 사회. 문화. 의료. 복지. 교육. 노동. 외교 등 사회 전반에 걸친 생활문화 혁명이 실현될 것으로 전망된다. 이러한 시점에서 정보보호는 u-Korea 실현의 중요한 핵심 엔진 기술로써u-Korea 전략 추진의 주요한 장애 요인으로 예상되는 사생활 문제와 지역 간. 계층간 정보격차 문제 등의 정보화 역기능을 해소하는 역할을 수행해야 한다. 본 고에서는 정통부가 추진하고자 하는 u-Korea 기본 전략에 대해서 살펴보고, 안전한 u-Korea 실현을 위해서 구체적인 정보화 역기능 방지 대책을 제안한다. 특히, BcN 인프라 보호 기술, RFID/USN 개인 프라이버시 보호 기술, WiBro 및 DMB 등에서 사용되는 복합단말기용 통합 인증. 인가 기술, 안전한 사용자 서비스 제공을 위한 서비스 사용의 익명성과 서비스 관리의 실명성이 제공되는 보안위임서비스 기술 등으로 형성되는 “Security Belt” 정보화 역기능 방지 대책에 대해서 소개한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.01a
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• pp.361-363
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• 2019

인터넷환경에서 금융회사는 홈페이지 사용자의 신원확인, 부인방지 등의 목적으로 공개키 기반구조(PKI: Public Key Infrastructure) 환경의 공인인증서를 홈페이지 로그인, 전자금융거래 등의 업무에 적용하고 있다. 사용자의 공인인증서를 이용하여 생성된 전자서명이 악성코드 감염 등으로 인하여 유출 시 사용자가 과거에 서명했던 전자서명이 재사용(로그인, 전자금융거래 등)될 수 있는 취약점이 존재하기에 인터넷 상에서의 전자서명 재사용에 대한 원인, 방지 절차 및 방법을 제안 하고자 한다.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.159-160
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• 2013

본 논문에서는 연료전지를 사용하여 2차 전지를 충전시키는 동기식 부스트 컨버터를 제어하는 방식을 제안한다. 고효율을 위한 동기식 부스트 컨버터는 기존의 부스트 컨버터의 다이오드 대신 MOSFET을 사용한다. 이때 연료전지의 전압이 배터리의 전압보다 낮기 때문에 양방향 소자인 MOSFET의 특성상 DCM구간에서 역전류가 발생한다. 연료전지의 긴 기동시간으로 인해 초기 동작 시 소프트 스타트가 필요한데 이때 역전류가 발생할 수 있는 DCM구간이 나타난다. 시스템 제어를 위해 사용된 mode boundary detector은 CCM과 DCM을 구분해주어 컨버터를 제어한다. CCM구간에서는 동기식으로 부스트 컨버터가 동작되고 DCM구간에서는 기존의 다이오드를 사용하는 방식으로 역전류를 방지한다. 시뮬레이션을 통해 논문의 타당성을 증명하였다.