PURPOSES : This study provides fundamental information on the temperature variations in tunnel structures during severe fire events. A fire event in a tunnel can drastically increase the internal temperature, which can significantly affect its structural safety. METHODS : Numerical simulations that consider various fire conditions are more efficient than experimental tests. The fire dynamic simulator (FDS) software, based on computational fluid dynamics (CFD) and developed by the National Institute of Standards and Technology, was used for the simulations. The variables included single and multiple accidents involving heavy goods vehicles carrying 27,000 liters of diesel fuel. Additionally, the concrete material characteristics of heat conductivity and specific heat were included in the analysis. The temperatures of concrete were investigated at various locations, surfaces, and inside the concrete at different depths. The obtained temperatures were verified to determine whether they reached the limits provided by the Fire Resistance Design for Road Tunnel (MOLIT 2021). RESULTS : For a fire caused by 27,000 liters of diesel, the fire intensity, expressed as the heat release rate, was approximately 160 MW. The increase in the carrying capacity of the fire source did not significantly affect the fire intensity; however, it affected the duration of the fire. The maximum temperature of concrete surface in the tunnel was approximately 1400 ℃ at some distance away in a longitudinal direction from the location of fire (not directly above). The temperature inside the concrete was successfully analyzed using FDS. The temperature inside the concrete decreased as the conductivity decreased and the specific heat increased. According to the Fire Resistance Design for Road Tunnel (MOLIT 2021), the internal temperatures should be within 380 ℃ and 250 ℃ for concrete and reinforcing steel, respectively. The temperatures were found to be approximately 380 ℃ and 100 ℃ in mist cases at depths of 5 cm and 10 cm, respectively, inside the concrete. CONCLUSIONS : The fire simulation studies indicated that the location of the maximum temperature was not directly above the fire, possibly because of fire-frame movements. During the final stage of the fire, the location of the highest temperature was immediately above the fire. During the fire in a tunnel with 27,000 liters of diesel, the maximum fire intensity was approximately 160 MW. The capacity of the fire source did not significantly affect the fire intensity, but affected the duration. Provided the concrete cover about 6 cm and 10 cm, both concrete and reinforcing steel can meet the required temperature limits of the Fire Resistance Design for Road Tunnel (MOLIT 2021). However, the results from this study are based on a few assumptions. Therefore, further studies should be conducted to include more specific numerical simulations and experimental tests that consider other variables, including tunnel shapes, fire sources, and locations.

This study investigated the key factors that explain the continuous usage intention of mobile payment users in the post COVID-19 pandemic era. Based on the health belief model (HBM) and communication privacy management (CPM) theory, this study examined how the five constructs of HBM influence mobile payments continuous usage intention through perceived privacy risk and perceived security. It also investigated the moderating role of perceived privacy awareness on the relationship between perceived privacy risk and continuous usage intention as well as the moderating role of information sensitivity on the relationship between perceived security and continuous usage intention.

As the hydrofluoric acid leak at Gumi-si, Gyeongsangbuk-do or hydrochloric acid leak at Ulsan demonstrated that chemical related accidents were mostly caused by large amounts of volatile toxic substances leaked due to the damages of storage tank. The purpose of this study was to develop PFA lined bottom drain ball valve for using in semiconductor, LCD manufacturing fields, pharmaceutical and others. For this purpose, modeling and design of PFA lined bottom drain ball valve, casting mold and casting production, design and manufacturing of lining mold, design and manufacturing of lining jig, PFA forming and assembly have been carried out for 50A×25A PFA lined bottom drain ball valve. In addition, a performance test was performed for the pin hole, density, tensile strength, elongation and elastic modulus of the developed prototype. As a result, the performance of the prototype valve satisfies all the objects of this study. Also, the developed valve was a very good performance compared with conventional 50A×25A imported valve with the same size.

Recently, sewer–pipe constructions replacing deteriorated pipes are currently underway in the downtown area. To resolve many problems in the conventional method of open-cut construction, lining-board system using light-weight GFRP panels is developed. The pultruded GFRP panels can be successfully used for the developed lining-board system as temporary decks and retaining walls in virtue of light weight, high strength and high durability. In this paper, the structural safety and serviceability of the lining-board system are examined through FE analyses and experiments. Further more, a field application of the lining-board system is presented. The field application shows that quality and environment of construction can be significantly improved.

This study seeks to offer practical suggestions for manufacturing jacket lining patterns through research on menswear brands. A researcher conducted interviews with a survey instrument targeting 12 menswear brands. To analyze the data, descriptive statistics were obtained using SPSS 18.0. The main findings were as follows. First, regarding lining production, most menswear brands were found to provide jacket lining patterns to their subcontractors, and pattern makers were found to design lining patterns based on their own know-how. The most important factor in the production of jacket lining patterns is whether linings are cut more than once during the sewing process. For suit jackets, linings are cut more than once, and for casual jackets, linings are cut once. Second, with regard to jacket production for different jacket styles, most menswear brands were found to use patterns that include seam allowance. Partial linings showed differences in terms of the methods used to sew edges and attach linings to the outer shell. Third, extra space in jacket lining patterns varied according to style. Jacket lining patterns for suit jackets and casual jackets showed differences in extra space in the following areas: the parts that cover the chest(suit jacket linings: 5.6cm, casual jacket linings: 2.4cm), the parts that cover the waist(suit jacket linings: 3.8cm, casual jacket linings: 1.3cm), hem(suit jacket linings: 2.7cm, casual jacket linings: 1.3cm), and bicep(suit jacket linings: 2.7cm, casual jacket linings: 1.1cm). However, extra space in the sleeve hems was identical for the two styles(suit jacket linings: 0.1cm, casual jacket linings: 0.1cm). Therefore, this research suggests that clothing manufacturers design linings in accordance with the jacket lining production style.

A new material was developed to achieve improvement of heat durability, improvement of wear resistance, stability of friction coefficient and reduction in aggression to counterpart, because it is difficult to maintain braking properties by using currently available materials in the train wagons used for high-speed transportation. As a result, the new material showed a stable wear resistance even in the speed range of 350km/h, where improvement was also confirmed in reduction of aggression to counterpart material by more than approximately 10%. This development was adopted for the brake lining in the Taiwan High Speed Rail project.

In spite of unparalleled combination of essential material properties for brake linings and clutch facings, replacement for asbestos is seriously called for since it is a health hazard. Once asbestos is replaced with other material then composition and properties of brake pad changes. In certain cases hardness of the material may be high enough to affect the rotor material. In this study, hardness of the brake pad has been controlled using suitable reinforcement materials like glass, carbon and Kevlar pulp. Brake pad formulations were made using CNSL (cashew net shell liquid) modified phenolic resin as a binder, graphite or cashew dust as a friction modifier and barium sulphate, talc and wollastonite as fillers. Influence of each component on the hardness value has been studied and a proper formulation has been arrived at to obtain hardness values around 35 on Scleroscopic scale. Friction and wear properties of the respective brake pad materials have been measured on a dynamometer and their performance was evaluated.

지하구조물의 건전성을 평가하기 위한 비파괴시험으로써 탄성응력파를 이용한 충격반향탐사법을 수치해석적인 방법을 통하여 수행하였다. 즉, 일면만으로 접근 가능한 터널 면에서의 충격가진과 동적응답의 측정으로 이질면을 포함한 내부의 상태를 예측할 수 있다. 연구의 수행은 탄성거동을 하는 매질 내부에서 전파되는 탄성응력파의 특성을 이해하고, 이를 동적 유한요소해석으로 모형화하여 충격반향탐사법을 수치해석적으로 수행한다. 이질재료가 2개의 층을 이루고 있는 경우 표면층의 두께를 쉽게 측정할 수 있었으며, 구조물의 병진운동, 휨운동과 구조물 내에서 다중반사되는 탄성응력파에 의한 복합적인 영향을 받는 터널과 같은 원통형 구조물에서 동적응답의 주파수 특성으로부터 터널라이닝 내부에 형성된 공동의 위치와 크기의 예측이 가능하였다. 수치해석적인 방법과 병행하여 다양한 형태의 경계조건을 가지는 구조물에 대한 충격반향탐사법의 실험을 수행할 경우 실제적인 문제에 적용, 건전성 평가의 지표를 마련할 수 있을 것으로 사료된다.

Using GPR(Ground Penetrating Radar) Precise Inspection, the real lining thickness of the tunnel damage was determined and detailed analysis was performed to provide a more accurate structural safety assessment of the tunnel damage. Through this study, It is presented to provide a guide for the application of the tunnel for inspection and diagnosis.

Safety, Durability, and Usability of the Concrete Structure affecting among, there are crack and leakage the main damage is crack and leakage. Especially, Leakage is accompanied by Efflorescence, and provoke steel corrosion, exfoliation. This leakage is leaked to the exterior of the concrete surface in the shape of line or face, the method of repair varies with the shape of leakage. Accordingly, this paper will introduce case analysis of the shape of the water leakage to water leakage site in the lining structure of the NATM tunnel for utilize investigation method and basic data for the method of repair.(leakage, Efflorescence)

The clogging of transverse drainage pipes in NATM tunnel is attributed to the hydraulic pressure generated on the outside of lining concrete and affects the safety of the whole structure in the long term, necessitating a keen attention in terms of its maintenance. Accordingly, this paper will introduce an analysis on the effect of the clogging of transverse drainage pipes on the lining structure based on the comparison between the inspection of the clogging of transverse drainage pipes and the visual inspection (leakage, efflorescence).

Domestic facilities are managed in accordance with the "Special Law on the Safety and Maintenance of Facilities", and are managed through periodical inspection and safety diagnosis. In the inspection and diagnosis of such facilities, Comprehensive analysis results from exterior and non-destructive survey, and the five grade of the facility is managed. Most of the non-destructive tests are carried out in consideration of operation. In this paper, the purpose of this study is to investigate the change of compressive strength and the characteristics of the core strength in the ○○ tunnel.

It is necessary to establish countermeasures to prevent spalling in the tunnel ceiling concrete lining from being linked to lack of lining thickness, leading to additional spalling. We analyzed the effect of thinning between the ceiling part and the lining thickness on the safety of the tunnel and confirmed the structural behavior of the lining based on the measured values after practically reinforcing the inside and filling the inside of the lining.