• 가족자원경영과 정책
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• 제10권3호
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• pp.23-43
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• 2006

The purpose of this study is to identify the types of consumer problems involving the use of online game services in Korea. This study analyzed the consumer damage cases by age and type that were reported to the Korea Consumer Protection Board (KCPB). The results of this study are as follows: The online game complaints varied by age. In the case of children, most complaints involved phone charging online game fees without parents' consent. There were similarities in the victimization of teens and children according to reason for complaint, handling result and type of damage. However, based on method of charging, mobile phone and credit card payments were causes in the case of teen victimization. Meanwhile, complaints among adults showed more complexity than the previous two groups such as cases relating to online game companies illegally seizing game items and game accounts, and charging fees for unused services caused by identity theft. By type of charging method, most complaints involved phone and mobile phone payments. According to the analysis result of online game victims, the monetary damage of consumers did not differ among socio-demographic variables such as age, residence, gender and occupation but there was difference in the method of charging. In the handling period, differences could be seen by age, year, gender and type of damage.

• Smart Structures and Systems
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• 제8권4호
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• pp.385-398
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• 2011

This paper discusses the applicability of Acoustic Emission (AE) to assess the damage in reinforced concrete (RC) structures subjected to complex dynamic loadings such as those induced by earthquakes. The AE signals recorded during this type of event can be complicated due to the arbitrary and random nature of seismicity and the fact that the signals are highly contaminated by many spurious sources of noise. This paper demonstrates that by properly filtering the AE signals, a very good correlation can be found between AE and damage on the RC structure. The basic experimental data used for this research are the results of fourteen seismic simulations conducted with a shake table on an RC slab supported on four steel columns. The AE signals were recorded by several low-frequency piezoelectric sensors located on the bottom surface of the slab. The evolution of damage under increasing values of peak acceleration applied to the shake table was monitored in terms of AE and dissipated plastic strain energy. A strong correlation was found between the energy dissipated by the concrete through plastic deformations and the AE energy calculated after properly filtering the signals. For this reason, a procedure is proposed to analyze the AE measured in a RC structure during a seismic event so that it can be used for damage assessment.

• 한국터널지하공간학회 논문집
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• 제3권3호
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• pp.31-43
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• 2001

본 연구에서는 안전진단에 관한 기본적 정보를 제공하고 유사한 변상의 발생을 최소화하기 위한 목적으로 터널의 변상사례들에 대한 조사와 분석을 수행하였다. 국내외 터널의 44개 변상사례에 대하여 4개 항목 즉, 내용수명, 변상유형 및 원인, 지질상태 등에 관한 빈도 수를 분석하였다. 이와 더불어 국내 터널분야의 전문가들로부터 안전진단 평가에 관련하여 총 28개 항목에 대한 설문조사를 수행하였다. 본 연구의 결과는 터널의 변상항목 중에는 균열에 의한 변상이 42~58% 정도로 가장 높은 비율을 나타났다. 변상 원인으로는 시공불량에 의한 영향이 높은 비율을 나타내고 있으므로 시공품질의 확보가 중요한 요인으로 사료된다. 설문조사 결과로부터 경직된 평가기준의 완화를 지적하였다. 그리고 각 항목별 중요도를 제시함으로써 인공지능기법 등을 안전진단분야에 적용하기 위한 기초자료로 활용될 수 있을 것이다.

• 한국지반공학회논문집
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• 제23권7호
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• pp.77-86
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• 2007

실내 시험기에 의하여 3가지 타입의 지오그리드의 시공 시 손상을 압밀조건에 따라 평가하였다. 이 실험은 ENV ISO 10722-1에 근거하여 실행되었다. 우선 실험에 사용된 흙 입자의 입도분석과 함수비를 측정하였다. 그리고 내시공성에 영향을 주는 인자로서 반복하중과 지오그리드의 타입을 변화시켰다. 실험에 사용된 시료는 6, 8, 10T woven, warp-knitted, welded type의 지오그리드이다. 이 실험은 반복하중과 감소계수의 관계를 설명하기 규명하기 위하여 진행되었다. 실험 결과 반복하중은 지오그리드의 손상과 밀접한 관련이 있었다. 특히, welded type의 지오그리드의 경우는 다른 종류의 지오그리드보다 더 낮은 감소경향을 보였는데 이는 coating material 때문이다. 즉 welded type의 지오그리드는 피복 재료가 PP이나 나머지 다른 두 종류의 경우 PVC로 되어있다. 다짐 횟수 이외의 감소 계수를 측정하기 위하여 실험을 하였다. 흙 입자의 크기가 9.5mm이상 23.5mm이하인 자갈을 가지고 다시 내시공성 시험을 하였다. 시료 포설 전 흙의 다짐 횟수를 200회로 하였으며, 그 이유는 이때의 감소계수가 다른 조건보다 더 크기 때문이었다.

• International Journal of Concrete Structures and Materials
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• 제6권3호
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• pp.199-207
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• 2012

Concrete is an economical construction material and for that reason it is widely used in buildings and infrastructures. The use of deicing salts, expansion joint failure, and freeze-thaw cycles have led to concrete bridge girders experiencing corrosion of steel reinforcement and becoming unsafe for driving. The goal of this research is to assess the effectiveness of current and possible repair techniques for the end region of damaged prestressed concrete girders. To do this, three American Association of State Highway and Transportation prestressed concrete girders were tested to failure, repaired, and retested. Three different repair materials were tested including carbon fiber, glass fiber, and surface mounted rods. Each different repair material was also tested with and without injected epoxy. Comparisons were then made to determine if injecting epoxy had a positive effect on stiffness and strength recovery as well as which repair type regained the largest percentage of original strength.

• Journal of Chest Surgery
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• 제7권1호
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• pp.73-78
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• 1974

Influences on organ function were studied in animals during prolonged extracorporeal circulation with a bubble type of oxygenator. More than six hours of total cardiopulmonary bypass was performed under mild hypothermia by means of an extracorporeal circulation system in five dogs. Obtained results were summarized as follows. 1. The renal function was not so impaired seriously until four hours of extracorporeal circulation. However, there was more serious impairment of renal function in this study when extracorporeal circulation was carried out for a period of five hours or more. 2. There was gradual hepatic damage during extracorporeal circulation and the damage was more significant after bypass for a period of five to six hours. 3. There was a significant decrease in serum K during bypass, irrespective of the pump oxygenator prime with a high K solution. The reason for this is complex and due to many factors, however, it was evidently related to serum glucose levels during extracorporal circulation.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2005년도 추계 학술논문 발표대회
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• pp.51-54
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• 2005

The concrete structure hasn't perfect waterproofing performance but if it doesn't have a joint part that could isolate a permeability. Concrete structure(communication tunnel and underground structure) has an expansion joint and construction joint. There are a lot of joint type after construction or expansion, shrinkage, vibration, over load, performance of decline etc.. they offer a water of way by variety change. In this reason, It carries in effect a waterproofing work for the concrete structure of waterproofing. but the structure has a behavior that cause a problem by waterproofing layer of damage, heaving phenomenon, temperature of shrinkage. In this study, we will estimate a field of application for Sealer of injection type for leakage maintenance of construction standard on the waterproofing performance.

• 콘크리트학회논문집
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• 제19권1호
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• pp.27-37
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• 2007

이 연구의 목적은 초기재령 콘크리트가 동해를 입을 경우가 예상될 때, 동해저항성을 확보하는데 필요한 최소 양생 시간의 예측법을 제안하는 것이다. 먼저, 실험을 통하여 동해시점이 지연될수록, w/c가 낮을수록, 그리고 1종 시멘트보다 3종 시멘트를 사용한 콘크리트가 동해에 의한 압축강도 감소율이 낮으며 동해는 얼음결정의 형성과 성장을 통해 발생됨을 확인하였다. 초기재령 콘크리트가 동해를 입었을 경우, 콘크리트 내에 존재하는 모세공극의 자유수가 얼음으로 상변화를 일으키면서 압축강도의 감소를 유발하므로 동해저항성은 모세공극의 포화도에 따라 결정된다. 따라서, 모세공극의 임계포화도 개념을 근거로 초기동해의 방지를 위한 최소양생시간의 예측법을 제안하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.530-537
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• 2006

Recently, the railroad route plan is trying to minimize the damage of the local resident which is caused by railroad construction. For this reason, reducing the banking height of soil roadbed, lowering the bridge girder height of a solid intersection and a part of cross river, the through bridge type which can achieve a required span length must apply. The representative through bridges of railroad are arch bridges, truss bridges and plate girder bridges, the through plate girder bridge of variable section can apply that the span length of these bridges is about $30{\sim}50m$, namely, middle span length bridge types, and that can satisfy structural capacity and beauty of railroad at the same time. This paper introduces plan and design process of the Su-eo cheon bridge applied by a through plate girder bridge type of the Jinju-Gwangyang double track 6th construction ordered at Korea Rail network Authority in 2005.

• Journal of Biosystems Engineering
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• 제28권1호
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• pp.35-44
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• 2003

This study was conducted to develop proper model for cold storage facility that could of for uniform heat movement and air movement f3r green grocery and improve improper design of the existing container-type cold storage facility. For that reason, new model(dome-type) cold storage facility was developed using 3-D CFD(computational fluid dynamics) simulation. The size was 6m${\times}$6m${\times}$5m. Its size and configuration were same to simulation model. Unit cooler was designed to send cold air in 4 side ways. A dome-type cold storage facility showed uniform distributions of air temperature and velocity because cold air was forced to move down along the ceiling and the wall and then circulated to the unit cooler from the central part of the floor. Dome-type cold storage facility also showed by low wind velocity, below 1 m/s that could minimized cold damage and quality deterioration.