• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.3
• /
• pp.157-164
• /
• 2016

The performance of convective heat transfer in rod bundle flow was experimentally evaluated using a twist-vane spacer grid. A $4{\times}4$ square-arrayed rod bundle was prepared as the test section, with a pitch-to-diameter ratio(P/D) of ~1.35. To check the convective heat transfer performance, the circumferential and longitudinal variations in rod-wall temperatures were measured downstream of the twist-vane spacer grid. In the circumferential measurements, the rod-wall temperature toward the twist-vane tip showed the lowest value, which might be due to the deflected water flow caused by the twist-vane. On the other hand, the wall temperature of the longitudinal measurements near the twist-vane spacer grid decreased dramatically, which implies that the convective heat transfer performance was enhanced. A heat transfer enhancement of ~35 % was achieved near downstream of the twist-vane spacer grid, as compared with the upstream value. Based on the present experimental data, a correlation for predicting the heat transfer performance of a twist-vane spacer grid was proposed.

• KIEAE Journal
• /
• v.16 no.4
• /
• pp.41-46
• /
• 2016

Purpose: This is a study on the planning of temporary housing for post application of Mega Sports facilities. The subject of the study is 2018 Pyeongchang Winter Olympics, which is to suggest building an alternative temporary housing using shipping containers(high cube), which solve the lack of accommodations and recycle temporary housing after Olympics, save money and be eco-friendly in Olympics. Method: This study includes this ; research on the a fact-finding survey about Mega sports facilities post application and demand survey on 2018 Pyeongchang Winter Olympics accomodations and an analysis about temporary housing plan. Furthermore we decided temporary housing building plan by analyzing residents' needs and traits of the housing etc. Through this, we made a schematic design for household units. Result: As a result, this study is a plan of making space, forms, and structure. The planned size is $38.4m^2$(L:12m, W:3.2m) except balcony, and indoor height is 2.5m. The space consists of entrance, bathroom, bedroom and living room with folding furniture system. Also there's a detailed floor plan of the ceiling, wall, and floor we drew up. The ceiling and wall consist of dampproof film, noncombustible board, fire proof urethane form, and color-designed sheet. The floor is composed of floor tile, cement mortar, light concrete(with heat coil), insulation, and dampproof film. Additionally, this study is a plan of interior dry wall with detail using modular construction method for work efficiency and quality improvement.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.15 no.3
• /
• pp.301-310
• /
• 2013

Jet fans are installed in road tunnels in order to maintain critical velocity when fire occurs. Generally the number of jet fans against fire are calculated by considering critical velocity and flow resistance by wall friction, vehicle drag force, thermal buoyance force and natural wind. In domestic case, thermal buoyance force is not considered in estimating the number of jet fans. So, in this study, we investigated the pressure loss due to the thermal buoyance force induced by tunnel air temperature rise and the impact of thermal buoyance force on the number of jet fans by the numerical fire simulation for the tunnel length(500, 750, 1000, 1500, 2000, 3500m) and grade (-1.0, -1.5, -2.0%). Considering the thermal buoyance force, number of jet fans have to be increased. Especially in the case of 100MW of heat release rate, the pressure loss due to thermal buoyance force exceed the maximum pressure loss due to vehicle drag resistance, so it is analyzed that number of 2~11 jet fans are needed additionally than current design criteria. Thus, in case of estimating the number of jet fans, it must be considered of thermal buoyance force induced tunnel air temperature rise by fire.

• KIEAE Journal
• /
• v.15 no.6
• /
• pp.11-18
• /
• 2015

Purpose: The current study analyzed trends in thermal insulation performance with aging, and condensation characteristics caused by the former. Method: Thermal insulation and condensation prevention performance of an architecture were assessed using Temperature Difference Ration Inside, or TDRi. Subjects of this quantitative analysis in thermal insulation performance change due to aging included recently constructed apartments and aged apartments older than 40 years. Time series comparison and analysis were conducted to observed changes in the thermal insulation performance and condensation characteristics. Result: Analysis showed that wall insulation performance degraded with aging regardless of fortified insulating material usage or insulating material type, which caused increased danger of condensation. In addition, when fortified insulating material was installed on the connection between the walls, insulation performance degradation was lower compared to cases in which fortified materials were not used. In all cases from 1 to 10, the rate of thermal insulation performance degradation increased after 20 years of aging.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.11c
• /
• pp.2227-2230
• /
• 2002

본 논문에서는 WWW을 이용한 전자상거래 환경(B2B, B2C, 등)에서 기업간(시스템 사이) 원활한 업무 협조와 just-in-time 서비스를 구현할 수 있도록, 능동 데이터베이스 기법을 이용한 전자상거래 시스템의 능동 kernel을 제안한다. 능동 커널은 고수준(high level)의 규칙 프로그래밍 언어(ECA rule)를 제공하므로 응용 프로그램과는 독립적으로 기업간 업무협조(coordination)와 사건 기반의 just-in-time 서비스를 구현할 수 있다. 따라서 시스템 관리자 및 프로그래머는 전자상거래 시스템간 조정 기능 구현과 유지보수를 쉽게 할 수 있다. 또한, 본 논문에서 제안하는 능동 커널은 기업의 방화벽(fire-wall)을 통해서도 적용될 수 있도록 HTTP 프로토콜을 이용하므로, platform 독립적인 구현을 통하여 기업간 시스템의 보안 유지와 독립성을 보장할 수 있다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.05b
• /
• pp.29-32
• /
• 2006

The techniques related to ultra-high strength concrete(UHSC) became the key issue in recent days since requirements of the high-rise building which story is over than 100 gradually increases. Therefore, for the development of 150MPa UHSC this research is generally categorized by 4 parts: development of pre-mixed binders, evaluation for the fire performance of coarse aggregate, optimization of the mixture proportion, and mock-up test. Finally, based on the optimized mixture and its laboratory tests, mock-up test for wall and column specimens were carried out to simulate and evaluate the UHSC in real situation. The mechanical properties of core specimens were compared with the cylinder specimens made in laboratory. For instance, it showed the reasonable the results that the strength at the age of 91 days is 183MPa.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2004.04a
• /
• pp.55-58
• /
• 2004

Phenolin resin, prepared form phenol and formaldehyde, is one of the oldest thermosetting resins available. Phenolic resins are cured via condensation polymerization with evolution of water, which in molding process is a big problem. The use of phenolic resins in glass fiber composites is growing, primarily due to their low flame spread, low smoke generation and low smoke toxicity properties. SMC of phenolics has been rearched since the 1986. The technology challenge was to match resin viscosity, handling and cure with those for the polyester SMC to avoid any special processing for fabricators and end users. Phenolic SMC was chosen because of the ease of molding to the required shape with light- weight, thin wall structure and with excellent fire protection.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.4 no.1
• /
• pp.261-266
• /
• 2000

The password is the first step for computer security. If security of password is unimportant even constructing of fire-wall, it is useless. But end-user is not able to manage a high-difficulty password. So complement for password management is needed. In this paper, algorithm which produces one time password by using random number in client is used. Not oかy this is easy for end-user to manage password, but also this can eliminate insecurity for server hacking.

• Korean Institute of Interior Design Journal
• /
• v.15 no.1 s.54
• /
• pp.158-165
• /
• 2006

The space of leisure boats & yachts is formed by interior design elements and shapes are formed by combination of those elements. By means of configuration of the design elements, space is made in a ship and patterns in an inside space are made through production. These space can be categorized as (1) cabin(common cabin, staterooms, one-cabin), (2) salon, (3) galleys & dinette, (4) heads(showers, toilets, bidets, sinks), (5) cockpit, (6) wheelhouses, navigation stations, (7) fore peaks, (8) engine room, (9) deck etc. Interior materials are classified into (1) walls(bulkheads & lining wall), (2) floors(sole), (3) ceilings(overheads), (4) doors & windows, (5) furniture, (6) lightings and (7) Hardware & decoration in large, medium and small sizes, which constitute interior design elements of a leisure boat & yacht. The materials used in leisure boats & yachts have properties of lightweight, noise and vibration resistance, fire & flame retardant, stability, strengths, lifespan, appearance and special operation in construction.

• Design & Manufacturing
• /
• v.13 no.1
• /
• pp.42-47
• /
• 2019

Nucleate boiling heat transfer is one of the most important phenomenon in the various industries. Especially, critical heat flux (CHF) refers to the upper limit of the pool boiling heat transfer region. Therefore, many researchers have found that CHF can be significantly increased by adding very small amounts of nanoparticles. In this study, the CHF and heat transfer coefficient were tested under the pool boiling state using copper and multi wall carbon nanotube nanoparticles. The results showed that two different types of nanoparticles deposited on the surface of two specimens made of the same material increased the heat flux in the nanoparticles with high conductivity, and there was no difference in the critical heat flux when the same material nanoparticles were deposited on the two different specimen surfaces.