• Journal of Family Resource Management and Policy Review
• /
• v.10 no.3
• /
• pp.23-43
• /
• 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
• /
• v.8 no.4
• /
• pp.385-398
• /
• 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.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.3 no.3
• /
• pp.31-43
• /
• 2001

In this study, we carried out investigation and analysis on damages in tunnels on order to provide the basic information for the safety assessment of tunnels and to minimize the potential damage of the same kind as investigated. The frequencies of occurrence in terms of 4 items, i.e., service life interval, type of the damage, cause of the damage, and geological condition, were examined and summarized based on 44 foreign and domestic cases of tunnel damages. Also, we carried out a survey research of which the content included 28 questions on the tunnel safety assessment. The answers collected from domestic experts in tunneling suggested that the most probable cause of the tunnel damages was cracking in tunnels at 42~58%. They also suggested that the poor constrution work strongly caused the damages. Therefore, to ensure tunnel safety, high quality of constrution should be maintained as examined. The types of damage and their extent of influence on the overall tunnel safety are of practical importance to be used in the artficial intelligent system for tunnel safety assessment.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.7
• /
• pp.77-86
• /
• 2007

Installation damage of 3 types of geogrids was evaluated with compaction condition by laboratory tester. This experimental was in accordance with ENV ISO 10722-1. First, soil distribution and water content were conducted. And then we changed cyclic loading time and type of geogrids as a factor of installation damage. The samples are woven, warp-knitted, welded type of 6, 8, 10T. This study aims to give an insight into the relationships between installation damage and cyclic loading time. The result of studies was that strength of the damaged geogrids can be closely correlated with the time of loading cycles. Especially, welded type shows slower slope than two types of geogrids due to coating materials. That means welded type is coated with PP (Polypropylene), but the other two types of geogrids are coated with PVC (Polyvinyl Chloride). To confirm another factor different method was performed. The size of soil was used between 9.5 mm and 23.5 m to compare initial experimental. Cyclic loading compaction is taken 200 times before installation test and the reason is that the reduction factor of this case by installation damage was higher than other compaction loading conditions.

• International Journal of Concrete Structures and Materials
• /
• v.6 no.3
• /
• pp.199-207
• /
• 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
• /
• v.7 no.1
• /
• pp.73-78
• /
• 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.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2005.11a
• /
• pp.51-54
• /
• 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.

• Journal of the Korea Concrete Institute
• /
• v.19 no.1
• /
• pp.27-37
• /
• 2007

The purpose of this study is to propose a method to predict the minimum curing time of early age concrete required to prevent frost damage. Tests were performed to examine major factors, which affect the compressive strength of concrete frozen at early ages and investigate the source of frost damage at early age concrete. The results from the tests showed that the loss rate of compressive strength decreases as the beginning time of frost damage was delayed and water-cement ratio was lower. In addition, the test results also showed that concrete made with type III cement was less susceptible to frost damage than concrete made with ordinary Portland cement and frost damage occurred through the formation of ice lenses. When early age concrete is being damaged by frozen, a phase transition into ice of free water presented at the capillary pores of the concrete gives a reason for the decrease of compressive strength. Accordingly, the frost resistance of fresh concrete can be determined based on the saturation degree of the capillary pores. The method to predict the minimum curing time was suggested using the concept of critical saturation degree of the capillary pores.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.530-537
• /
• 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
• /
• v.28 no.1
• /
• pp.35-44
• /
• 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.