Evaluation of the Depth of Deteriorations in Concrete Bridge Decks with Asphalt Overlays Using Air-Coupled GPR

Ji-Young Rhee,Jae-Jin Choi2,Seong-Hoon Kee 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.3

In this recent work, a ground penetrating radar (GPR) technique was proposed to evaluate the deteriorated depth of concrete bridge decks with asphalt overlays in the Korea expressway network. Air-coupled GPR was utilized in the measurement of the relative permittivity of concrete on bridge decks with asphalt overlays and the electromagnetic (EM) wave attenuation of the concrete cover of top reinforcing bars (rebars) in the pilot bridge in public service. In addition, 13 core samples were obtained from the bridge deck to carry out a detailed survey that includes visual inspection of the deterioration and measurement of chloride content with depth. The validity of the GPR technique was examined by comparing it with the results of the field investigation. Moreover, the correlation of the deteriorated depth with either the relative permittivity or EM wave attenuation was established. Results show that a GPR signal analysis method based on a dual-criteria (relative permittivity and EM wave attenuation) is more effective in analyzing the deterioration characteristics and evaluating the deteriorated depth of concrete bridge decks with asphalt overlay compared to the analysis method based on one of the two GPR properties. Results of the field test are considered to be significant wherein it establishes a relationship between the GPR property and deterioration characteristics of the bridge decks. Moreover, results show the practical applicability of the GPR technique in evaluating the deteriorated depth of the bridge decks with asphalt overlay.

단면형상변화에 따른 점용접 부재의 에너지흡수 특성

최영민,차천석,김지훈,서현경,양인영 한국공작기계학회 2006 한국공작기계학회 추계학술대회논문집 Vol.2006 No.-

The front-end side members of vehicles absorb the most of the energy during the front-end collision. These side members are mostly consist of single hat shape. The side members absorb more energy under axial load if they have higher strength, and stable folding capacity (local buckling). When structural members are subjected to axial loadings, stress is concentrated on their edges. Thus, in this study, the energy absorption characteristics of the member were analyzed according to change of sectional shape for increase of strength. The side members consist of single hat, double hat, single cap and double cap section member. Based on the static test result of these side member, the impact simulation were carried out and compared with test result.

개념적 분석방법을 응용한 자연 한글 질의어 인터페이스에 관한 연구

최대우,강지훈 충남대학교 자연과학연구소 1987 忠南科學硏究誌 Vol.14 No.1

This thesis presents a model of Natural Hangul Database Front End that is the interface between natural language understanding and database queries. This system enables and users to get the right answers with less frustration, and little requirements for the technical support This system is divided into two parts. The language processing part of the system uses Conceptual Analysis that maps the natural language input into the representation of its meaning, and uses Conceptual Dependency theory as the representation of conceptual-level meaning to remove the ambiguity in processing the natural Hangul query. The other part contructs an adequate logic query that can be translated into the formal query for the relational database. Also included are discussions of the method to improve the system adaptability.

On the niche graph of -partial orde

최지훈 청주대학교 학술연구소 2019 淸大學術論集 Vol.33 No.-

어떤 유향그래프 D의 경쟁그래프는 를 꼭짓점의 집합으로 가지며, 두 꼭짓점  와 가 변으로 연결될 필요충분조건이 적당한 꼭짓점 ∈에 대하여 유향변   와  가 모두 에 존재하는 것으로 정의된다. 경쟁그래프 개념의 도입 이래로 수많은 변형된 개념이 새롭게 정의되고 연구되었는데, 그 중 하나가 바로 니치 그래프이다. 어떤 유향그래프 의 니치그래프란 와 동일한 꼭짓점의 집합을 가지며, 두 꼭짓점 와 가 변으로 연결될 필요충분조건이 적당한 꼭짓점 ∈에 대하여 유향변  와   가 모두 에 존재하거나 또는 유향변 와 가 모두 에 존재하는 것으로 정의 된다.

Inductive Matching Feed를 이용한 금속용 UHF대역 RFID Tag Antenna 설계

최지훈,양진모 대구대학교 정보통신연구소 2008 情報通信硏究 Vol.5 No.1

In this paper, a novel antenna for UHF-band RFID tag mountable on conductive objects is designed and manufactured. It generates high Q (Quality factor) between antenna and conductive object when general planar RFID tag antenna is mounting on conductive objects. This is because of parasitic capacitors generated between antenna and conductive object and capacitive impedance of RFID chip. This effect has many influence on impedance, frequency, and radiation efficiency of the antenna, so it brings a detection distance reduction. The propose of this paper is minimization of Q effect to improve the bandwidth, and to bring a compact geometry design.. A measured maximum detection distance is 4m when the designed antenna is mounting on metallic surface and a liquid. The impedance bandwidth is 60% at the center frequency(900MHz) and the gain is 4dBi. 본 연구에서는 전도성 물질에 부착 가능한 UHF대역의 RFID (Radio Frequency Identification) Tag 안테나를 설계 및 제작하였다. 일반적인 평면 타입의 RFID Tag 안테나의 경우 전도성 물질에 부착하였을 때, 안테나와 전도성 물질간의 기생 리액턴스 성분이 발생되고, RFID Chip 자체의 큰 허수 임피던스 값에 의해 높은 Q (Quality Factor) 값을 가지게 된다. 이러한 영향은 안테나의 임피던스와 공진 주파수가 변하며 방사효율 또한 변하게 되어 인식거리 저하를 가져온다. 본 연구에서는 Q 값에 의한 영향을 최소화하여 광대역화를 이루고, 안테나 구조를 간단히 하는 설계 방법을 제시하였다. 설계된 안테나를 제작하여 금속 표면 및 액체에 부착하였을 때 측정된 최대 인식 거리가 4m이다. 임피던스 대역폭()은 중심주파수(900MHz)에서 60%의 대역폭을 가졌으며, 이득이 4dBi로 우수한 성능을 나타내었다.

기능형 중재자 기반의 교육자원 서비스 시스템의 구현

최병석,오지훈,한성국 한국컴퓨터교육학회 2003 컴퓨터교육학회 논문지 Vol.6 No.4

대부분의 웹 기반의 교육 시스템은 교육 정보 제공에만 중점을 두고 있다. 웹이 점차 교육 정보를 제공하는 보편적인 기반이 되어 감에 따라서, 웹은 이제 정보 제공의 차원을 넘어 다양한 서비스를 제공하는 플랫폼으로 변모하고 있다. 이에 새롭게 변화된 웹 환경에 맞는 교육 서비스 모델이 시급히 요청되고 있다. 본 논문에서는 기존의 웹 기반 교육의 여러 한계성을 해결하기 위하여 새로운 기능형 중재자 기반의 교육자원 서비스 모델을 제시하고자 한다. 본 논문의 기능형 중재자기반의 교육자원 서비스 시스템은 웹상에 산재되어 있는 교육 자원들을 효율적으로 관리하고 사용자의 요청에 맞는 교육 서비스 정보를 제공하여 줌으로써, 교육 서비스 자원들의 재사용 효율과 생산성을 높일 수 있다 Most of web-based education systems are only to supply education information. As the web becomes the common basis to support the effective education, it is used for not only applying education information but also developing to the dimension to provide various services. The education service models prospering to the newly diverse environment are necessary. In this paper, a education resource service system based on functional broker is implemented to overcome the weakness of the traditional Web-based instruction. This paper shows that the web-based education service system such as functional broker can manage the varied education resources efficiently and so contribute to realize the life-long education.

무선 네트워크 환경에서 끊김 없는 개체 무관 핸드오버에 관한 연구

최지훈,김동일 東義大學校産業技術開發硏究所 2009 産業技術硏究誌 Vol.23 No.-

As a mobility support for IP have studied, Internet Engineering Task Force(ITEF) standardized the mobile IPv6 protocol. When a mobile node moves between networks, MIPv6 maintains connectivity to network and supports seamless communication, and these processes are called a Handover. IEEE 802.21 standardized MIH(Media Independent Handover) for seamless Handover. MIH used three services for Handover between low layer and upper layer . In this paper, we designed two modes on existing MIH for seamless Handover. We implemented a dual-interface mobile host(MH) model in network simulation2 (ns2) to evaluate how it performs in comparison with single-interface MH.

農村 靑少年의 家庭生活에 관한 價値觀

崔敏浩,鄭址雄,金性洙,李洛薰,金鎭模 서울大學校 農科大學 1985 서울대농학연구지 Vol.10 No.2

The purposes of the study were to investigate the values of the rural youth in relation to family living, and to compare changes in the values with the similar study of the reseacher of 1970 in Korea. Data were collected by undergraduate and graduate students of the Seoul National University from randomly selected 993 rural youths of 13 to 24 years of age through questionnaire method. The data were analyzed by HP 3000 Computer in the College of Agriculture, Seoul National University. Major statistical techniques used for the study were frequency, percentile, chi square test. Statistical significance was tested at 0.05 level. The major findings of the study were as follows; 1. It was revealed that values on family living were changed into modern democratic ideals from traditional Confucian values 2. The view of respondents that the first son should take care of parents has decreased from 32.8% in 1970 to 23.8% in 1984. The Respondents who think that one of sons should take care of parents has increased from 45.8% in 1970 to 60.8% in 1984. 3. The rate of respondents claiming that the head of a family should govern the family with authority and dignity has increased from 61.1%in 1970 to 68.3% in 1984. 4. The respondents claiming that the head of a family should decide the important things of family living dogmatically has decreased from 16.9% in 1970 to 8.1% in 1984. 5. The rate of respondents claiming that father should respect mother's opinion in family has increased from 78.6% in 1970 to 90.5% in 1984. 6. The rate of respondents claiming that fathers should understand the things of children with maximum degree has increased from 86.8% in 1970 to 93.8% in 1984.

축구동호회 참가자의 참가동기와 여가만족, 몰입경험과 생활만족의 관계

최지훈,이창섭 忠南大學校體育科學硏究所 2008 體育科學硏究誌 Vol.26 No.1

The purpose of the study was to analyze relations between participatory motivation, leisure satisfaction, immersion experiences and life satisfaction of participants in soccer clubs. To make a close inquiry into those relations this study utilized questionnaires and analyzed data collected through measurement of each variable with SPSS/Win 15.0 statistic program and Amos 7.0 program. With results of the study, the study induced the following conclusions: First, leisure satisfaction of participants in soccer clubs was increased as much as their participatory motivation gets high. Therefore, their participatory motivation had a significant effect on leisure satisfaction. Second, immersion experiences of participants in soccer clubs was highly frequent as much as four-scope frequency excepting self-improvement, a lower scope in participatory motive of participants in soccer clubs, gets high. Therefore, their participatory motivation had a significant effect on immersion experiences. Third, life satisfaction of participants in soccer clubs was highly frequent as much as four-scope frequency excepting self-improvement, a lower scope in participatory motive of participants in soccer clubs, gets high. Therefore, their participatory motivation had a significant effect on life satisfaction.

갑상선 기능항진증에 병발된 주기성 마비 3예

최지훈,최경숙,김기훈,박병현,조정구 圓光大學校 醫科學硏究所 2001 圓光醫科學 Vol.16 No.1-2

Thyrotoxic periodic paralysis is characterized by intermittent flaccid paralysis of skeletal muscle, lasting several hours. The underlying pathophysiology of the syndrome is not yet to be well characterized and remains controversal, but reflects altered potassium and calcium dynamics as well as certain morphologic characteristics within the muscle unit itself. It occurs primarily in Asian populations with an overwhelming male preponderance and a higher association of specific HLA antigens. Precipitating factors include high carbohydrate ingestion, exercise, trauma, infection, alcohol ingestion, administration of epinephrine, thyroid hormone, or corticosteroid. If hypokalemia is present, potassium administration may help abort the attack, but the only definitive treatment is formation of euthyroid state. We discribed two patients with hypokalemic thyrotoxic periodic paralysis and one patient with normokalemic thyrotoxic periodic paralysis.