It is known that sewer problems are the major causes of road cave-in. The objective of this study is to analyze the risk of road cave-in due to storm sewer laterals. We investigated 174 storm sewer laterals using a zoom camera at O-dong area in Seoul. The causes of road cave-in were classified into five cases: breakage of rigid pipe, deformation of flexible pipe, out of pipeline alignment, changing pipe material or changing pipe diameter, and a poor linkage between lateral and sewer. In addition, all defects were sorted into five grades based on the severity rating at storm sewer laterals. In this study, the most fragile pipe materials were found to be concrete pipe and polyethylene pipe, which recorded 2.3 and 1.69 defect rates. With regard to the causes of road cave-in, deformation of flexible pipe has a large influence on road cave-in at present. On a long-term basis, the two causes, out of pipeline alignment and a poor linkage between lateral and sewer, could have more influence on road cave-in.

목 적 : 중증 외상환자나 급성 뇌졸중 환자와 같이 호흡이 불안정한 환자에 대한 MRI 검사가 증가하면서 인공호흡기 사용 환자의 영상 quality를 높이기 위한 여러 방법이 논의되었고, 연장관을 이용한 수동식 인공호흡기에 one-way valve를 기관지 삽입관에 직접 연결하는 방식이 가장 우수한 영상 quality를 만들어 낸다는 연구결과도 있었다. 하지만 기존의 연장관 연결 방식 사용 시 시간이 지날수록 환자의 호흡상태가 불량해지는 원인에 대한 정확한 인식이 부족하였고, 수동식 인공호흡기(Ambu)에 연결되어 있는 one-way valve를 분리사용 시 연장관과의 직경이 맞지 않는 등, 연결에 불편을 초래하여 이를 개선하고자 본 연구를 시작하게 되었다. 대상 및 방법 : 본원의 중증외상센터에 입원 중인 인공호흡기 치료 환자를 대상으로 수동식 인공호흡기에 연장관만을 연결하여 MRI검사를 시행하면서 동맥혈가스검사(ABGA)를 검사 초기에 3회 시행하였고, 검사 시작 30분후에 본원에서 제안한 연장관(one-way valve일체형)에 수동식 인공호흡기를 연결하여 동맥혈가스검사(ABGA)를 2회 재시행하여 전후의 혈액 속 산소량과 이산화탄소량을 측정하였다. (동맥혈가스 검사는 본원의 중증외상팀의 협조 아래 A-Line이 연결되어 있는 환자에게 시행되었다.) 결 과 : 기존의 수동식 인공호흡기에 연장관을 연결한 방법이 사용된 30분에서는 혈액 속 산소량과 이산화탄소량이 각각 300~200, 45~80으로 정상범위인 85~100, 35~45를 벗어나 급격하게 증가하는 양상을 볼 수 있었고, 호흡불안정으로 인해 영상의 quality가 떨어지는 결과가 나왔다. 이후 본원에서 제안한 one-way valve일체형 연장관이 사용된 검사에서는 혈액 속 산소량과 이산화탄소량이 모두 정상치를 보임을 알 수 있었고, 환자의 호흡이 안정되어 보다 높은 quality의 영상을 얻을 수 있었다. 결 론 : 잘못된 연장관 사용에 의해 환자가 배출한 이산화탄소가 외부로 배출되지 못하고 다시 환자에게 공급되면서, 혈액 속에 이산화탄소의 증가로 환자의 PH는 산성으로 바뀌며, 환자는 고통을 느끼게 되어, 뇌에서는 호흡 횟수를 증가시키도록 지시한다. 이러한 이산화탄소 Retention에 기인한 Expiration Time의 감소가 호흡불안정과 움직임에 의한 영상 quality의 저하로 이어진 것으로 사료된다. 본원에서 제안한 개선 방식에서는 혈액 속 산소량과 이산화탄소량이 적정하게 유지됨으로써 환자의 호흡도 안정되고, 영상의 quality 또한 높아 졌으며, 수동식 인공호흡기에 연결되어 있는 one-way valve의 위치를 바꾸는 경우보다 쉽고 빠르게 수동식 인공호흡기를 연결할 수 있어 환자의 안전과 영상의 quality 향상에 도움이 될 것으로 판단된다.

Due to the advantageous mechanical properties of the fiber reinforced polymeric plastics(FRP), their application in the construction industries is ever increasing trend, as a substitute of structural steel which is highly vulnerable under hazardous environmental conditions (i.e., corrosion, humidity, etc.). In this study, hybrid FRP-concrete composite pile (HCFFT) connection is suggested. The HCFFT is consisted of pultruded FRP unit module, filament wound FRP which is in the outside of mandrel composed of circular shaped assembly of pultruded FRP unit modules, and concrete which is casted inside of the circular tube shaped hybrid FRP pile. Therefore, pultruded FRP can increase the flexural load carrying capacity, filament wound FRP and concrete filled inside can increase axial load carrying capacity. In the study, connection capacity of HCFFT(small and mid size) is investigated throughout experiments and finite element method. From the results of experiments, we suggested the connection methods about HCFFT pile connection.

In this study, circular sectional concrete-filled tube(CFT) column-to-foundation connections were numerically investigated in order to improve their structural details. A inner reinforced specimen with high-tension bolts and inner deformed bars was adopted from a previous experimental study to make the numerical model. The validity of the numerical method was verified through comparing the experimental results with the analysis’s ones. In order to optimize design variables about the inner reinforced model, a number of numerical analyses were conducted for various variables. Finally, this study suggested the optimum variables about the reinforced circular sectional CFT column-to-foundation connections.

An experimental study on the structural behavior of connection types between approach slab and integral abutment has been done for three typical bar connections. Typical hinge style reinforcing bar detail for its connection is preferred in order to accommodate rotation of the approach slab among engineers. However, the straight horizontal bars can be used as connection detail accomodate structural capacity. Total six specimens with three types of rebar detail are tested for direct tensile and bending load. The characteristic structural behaviors are carefully monitored and all the strain gauge data obtained are analyzed. It is shown that the structural performance of all the specimens well exceed its design allowance. Several design suggestions are given based on careful reviews on the experiment.

PURPOSES: Safety consciousness can be the first factor to hinder the acceptance of design alternative, which moderates the applied design criteria in order to adapt the road to the natural terrain condition. METHODS : The method which enables to check the safety of design alternative by using design consistency concept is suggested. The method is based on the linked or interactive analysis between terrain and road alignment. Real design example is considered as a guide how to apply the method and the analysis result is discussed with the future research. RESULTS: Suggested method can be used for designers as a tool to review their design outputs can be safe as much as the original design. So, designers have the more objective judgement on their designs and have the confidence on their designs. CONCLUSIONS : The method is expected to be used as a tool to see the safety consciousness in an objective view, so any possible conflicts between designers and design-related personnels caused by the terrain-oriented design can be solved.

Fiber reinforced plastic (FRP) structural shapes are readily available in civil engineering applications. Among many manufacturing techniques used for FRP structural shapes, pultrusion process is one of the most widely used techniques in civil engineering applications. Pultrusion is a manufacturing process for producing continuous lengths of reinforced polymeric plastic structural shapes with constant cross-section. Pultruded composites are attractive for structural applications because of their continuous mass production with excellent mechanical properties. This paper presents the results of investigations pertaining to the bolted connection with two bolts for the pultruded FRP (PFRP) structural members. PFRP bolted connection tests were conducted with end distance to bolt diameter ratio (e1/db) and two types of bolt pattern such as horizontal (Pattern A) and vertical arrangement (Pattern B). As a result, it is found that the e1/db is recommended as the ratio of 4. In addition, it is also found that the bearing strengths at failure of the Pattern A and Pattern B have a similar value.

In everyday network changing field, permanent service is being an issue. Network disconnection phenomenon is directed to financial damage to service providers. Some companies guarantee on network maintenance, but there is a permitted limit according to their company regulations. If customers overuse the limitation, extra pay will be placed. Moreover, network disconnection affects critical in some fields with using network. Permanent service becomes indispensable in stock, finance, online game, and other fields. Additionally, it should be possible to pre-detect and block abnormal traffic area, improve network infrastructure secureness and optimization, and reduce damage recovery cost. MCS(Multi Connection System) can provide permanent service even if a connection is cut because it provides multi-connection. It can also isolate the attacker when it detects DDoS attack, so it provides smooth service. Also, the benefit from this structure is that the real server can be hidden so the service can be provided continuously. It prevents damages from network cutting, reduces management cost, maintains the best performance, and increases convenient on management and maintenance. Stable and continuous service can be provided with managing network through MCS.

The purpose of this study is to examine the effects of focus-on-form approach on learning connective ending '-느라고' of Korean language learners. Input enhancement and consciousness raising tasks were applied and compared as an effective way of this grammar instruction among various techniques of focus-on-form approach. The participants in the study are intermediate-level Korean language learners. They were divided into two groups, and teaching activities were provided undertaken based on two different methods. According to the results, significant differences were not found between the two methods, but the upper-level students had higher achievements than the lower-level students. Although no significant difference was found between the input enhancement and consciousness raising tasks, it was found that the focus-on-form approach can be recommended as a way to teach grammar effectively, especially it is effective for upper-level learners.

A methodology to evaluate the seismic performance of interface piping systems that cross the isolation interface in the seismically isolated nuclear power plant (NPP) was developed. The developed methodology was applied to the safety-related interface piping system to demonstrate the seismic performance of the target piping system. Not only the seismic performance for the design level earthquakes but also the performance for the beyond design level earthquakes were evaluated. Two artificial seismic ground input motions which were matched to the design response spectra and two historical earthquake ground motions were used for the seismic analysis of piping system. The preliminary performance evaluation results show that the excessive relative displacements can occur in the seismically isolated piping system. If the input ground motion contained relatively high energy in the low frequency region, we could find that the stress response of the piping system exceed the allowable stress level even though the intensity of the input ground motion is equal to the design level earthquake. The structural responses and seismic performances of piping system were varied sensitively with respect to the intensities and frequency contents of input ground motions. Therefore, for the application of isolation system to NPPs and the verification of the safety of piping system, the seismic performance of the piping system subjected to the earthquake at the target NPP site should be evaluated firstly.

Diagonal reinforced coupling beam of coupled shear walls can provide sufficient strength and stiffness to resist lateral force. However, the reinforcement details for coupling beams required by ACI 318 (2011) are difficult to construct because of the reinforcement congestion and confined interior area. This study presents experimental results about the seismic performance of coupling beams having bundled diagonal reinforcement to improve the workability. Experiments were conducted using half scaled precast coupling beams having an aspect ratio of 2.0. It was observed that the bundled diagonal reinforced coupling beams can develop seismic performance similar to the coupling beams with requirement details specified in ACI 318 (2011).

It has been more than twenty years since the application of GFRP bridge decks in construction fields. Recently, a few studies by governments and individual researchers have investigated in-use GFRP bridge decks. Areas of trouble include the problems of cracking, spalling and the de-bonding of the pavement or the wearing surface on GFRP bridge decks, all of which affect the long-term durability and serviceability of these new construction materials. Related to these problems, reflective cracks on asphalt pavement are directly related to pultruded GFRP bridge decks. This study investigates the behavior of an adhesive joint under weak-axis bending by tests and FE analyses to identify the causes of pavement cracks in in-use pultruded GFRP bridge decks. In detail, the flexural stiffness and the load-carrying capacities in strong and weak axes are measured during bending tests on pultruded GFRP decks. Next, tensile local failures of an epoxy adhesive due to the concentration of deformations at adhesive joints are identified via a weak-axis bending test. Finally, the tensile failure of an epoxy adhesive due to the local concentration of deformation at an adhesive joint under weak-axis bending is verified through a finite element analysis.

In recent days composite bridge decks are increasingly used to new and rehabilitated bridges due to their many advantages such as light weight, high strength, high durability, low maintenance costs and fast installation. To further promote usage of composite bridge decks, the authors have developed decks of new profile having innovative vertical snap-fit connection. Through this development, significant enhancement of constructability and economy are obtained by overcoming the drawbacks of conventional composite decks of tongue-and-groove connection. The paper introduces some research results and notable applications for the developed composite decks of snap-fit connection using for pedestrian bridges. Owing to their considerable advantages of the developed composite decks, increasing number of applications is currently underway in Korea.

The hysteretic behavior of diagonal reinforced coupling beams is excellent during earthquakes. However, construction of the diagonal reinforced coupling beams is difficult due to complex reinforcement details required by current code procedures (ACI 318-11). Due to the detail requirement, reinforcement congestion and interference among transverse reinforcement always occur during construction field. When the aspect ratio of the beam is large, the interference of reinforcement becomes more serious. The objective of this paper is to simplify the reinforcement details of slender coupling beams by reducing transverse reinforcement around the beam perimeter. For this purpose, high- performance fiber reinforced cementitious composites are used for making coupling beams. Experiments were conducted using three specimens having aspect ratio 3.5. Test results showed that HPFRCC coupling beams with half the transverse reinforcement required by ACI 318-11 provided identical seismic capacities to the corresponding coupling beams having requirement satisfying the requirement specified in ACI 318-11.

본 논문에서는 일체식 교대 교량의 장대화 및 내진성능 향상을 위해 가장 중요한 역할을 하는 교대-H형 강말뚝 연결부의 성능을 향상시키기 위하여 기존의 연결부의 균열형상을 파악하고, 이를 기반으로 새로운 형태의 연결부를 제안하기 위하여 철근을 활용하여 강성을 증가시키는 방법과 강말뚝의 형상을 개선하여 연성을 개선시키는 방법을 모색하였다. 먼저, 기존 연결부의 성능을 향상시키기 위하여 연결부 주변에 PennDOT에 규정된 철근상세와 나선철근의 배치와 HSS 튜브를 사용하였으나, PennDOT의 철근 상세와 HSS 튜브는 연결부의 성능을 향상시키지 못 했으나, 나선철근은 균열을 효과적으로 차단시키는 것을 확인할 수 있었다. 하지만, 철근의 구속효과로 인해 강말뚝의 저항력이 변위에 선형적으로 비례하여 증가하므로 교량의 상부구조에 축력을 발생시키는 효과를 가져왔다. 따라서, 강말뚝의 형상을 개선하기 위하여 콘크리트 교대에 매입된 부분의 플랜지를 제거하는 방법과 콘크리트 외부에서 플랜지의 폭을 축소시키는 형태를 검토하였다. 두 가지 방안 모두 균열을 억제하는데 효과적인 방법이었으나, 플랜지를 제거하는 쪽의 연결부가 더욱 효과적이었다.

The purpose of this research is to analyse the research subject in journal of Korean safety management and sciences. Total 1850 key words in 560 papers were analysed by the Pajek system which is one of well known social network analysis tool. Key words trend from 2008 to 2012 was examined. Then the relationship among each key words was visualized. There were five key words group which strongly connected among key words. The degree centrality, between centrality, proximity prestige on each key words were calculated to verify influence degree to other key words.

본 연구의 목적은 소집단 활동에서 과학영재들의 의사소통 구조를 찾아보고, 이들의 의사소통 유형과 성취 수준의 관계를 알아보기 위한 것이다. 이를 위하여 과학영재들을 대상으로 5명을 한 단위로 하는 8개 소집단을 구성하고, 이들에게 지구의 밀도 구하기라는 주제로 토론식 수업을 적용하였다. Pajek과 UCINET 6.0을 활용하여 과학영재들의 대화로부터 의사소통 구조와 성취 수준을 분석하였다. 그 결과 상호작용 분산 정도에 따라 과학영재들의 의사소통 유형을 독점형과 공유형으로 분류할 수 있었다. 그리고 상호작용 밀도와 집중도에 따라 과학영재들의 의사소통 유형을 DH·NH형, DH·NL형, DL·NH형, DL·NL형으로 분류할 수 있었다. 과학영재들의 소집단 활동에서 문제 해결 성취 수준은 구성원 간 상호작용의 분산이 아니라 상호작용의 밀도와 연결망 집중도의 차에 의해 영향을 받는다는 것을 알 수 있었다. 그러므로 교사들은 소집단 활동을 활용하여 학생들을 지도할 때 문제 해결에 관련된 의사소통이 이루어지도록 지도할 필요가 있다.

본 연구는 다양한 기상변화에 따른 안전을 확보하기 위한 해상에서의 플로팅 플랫폼의 연결에 대하여 연구하였다. 본 연구의 목적은 다양한 해상변화가 일어나는 연안역에 설치되는 플로팅 구조물에 관한 문헌 조사를 실시한 후, 콘크리트 구조물 연결하는 모델을 제시하는 것이다. 본 연구에서는 플로팅 구조의 개념, 기존의 모델, 설계적 평가를 포함한 콘크리트 구조물 기반 플로팅 플랫폼을 기술하였고, Rigid Pontoon Connector를 국내 연안역에 적합한 모델로 제안하였다. 연구의 결과로서, 리기드 폰툰 커넥터 디자인은 (Rigid Pontoon Connector) 안정적으로 플로팅 플랫폼의 연결을 구축할 수 있는 매우 효율적이고 실용적인 솔루션으로 분석되었다.

본 연구는 두루미(Grus japonensis)의 이용분포 내에서 행동권 분석의 기법인 MCP(최소볼록다각형법), KDE(커널밀도측정법), LoCoH(국지근린지점외곽연결)를 이용하여 이용면적과 핵심서식지를 선정하였다. 또한, 각 기법의 차이와 의미를 고찰하도록 하였다. 두루미의 분포자료는 철원지역 2012년 2월 17일 조사자료를 사용하였다. MCP에 의한 두루미류 서식영역은 140km2이었다. KDE 분석에서 띠폭에 해당하는 h값을 1000m, CVh, LSCVh로 달리하여 KDE 등치선을 생성하였을 때, 핵심지역에 해당하는(Kernel 50% 이상) 면적은 33.3km2(KDE1000m), 25.7km2(KDECVh), 19.7km2(KDELSCVh)이었다. 결과적으로 띠폭에 대한 기본값(1000m)-CVh(554.6m)-LSCVh(329.9m) 순으로 변수를 작게 입력할 경우 핵심면적 개수는 늘어나고, 면적은 감소하였으며, 형태의 복잡성은 증가하였다. 두루미류의 KDE 분석에 의한 핵심지역의 선정에서 적합한 띠폭변수는 CVh 값인 것으로 판단되었다. LoCoH분석에서는 서식범위와 핵심지역(50% 등치선 이상의 지역)의 면적이 k값의 증가에 따라 증가하는 모습을 보였으며, 점차 큰 핵심지역으로 합쳐지는 모습을 나타내었다. 핵심지역을 도출하기에 적합한 k 값은 24로 나타났으며, 전체 개체군의 핵심지역은 18.2km2로 전체 서식면적의 16.5%를 차지하였다. 최종적으로, LoCoH 분석은 두 개의 큰 핵심서식지를 제시하였으며, 이것은 KDE에 의한 핵심지역에 비하여 작은 수의 핵심지역을 제시한 것이었다. 국내의 게재논문 및 발표자료를 포함한 연구에서 KDE는 대부분 기본설정으로 분석되었으며, 띠폭에 의한 변수를 고려한 것은 매우 드물었다. 따라서 띠폭변수를 명확히 제시하는 것이 요구되었다.