• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.05a
• /
• pp.44-48
• /
• 2001

Tube hydroforming technology has increased dramatically, mainly by automotive industry in europe and the americas. It is required tube formability, optimized with regard to tribological factors and specially designed die and presses. In this process has many important parameters as expansion ratio of a tube, axial feeding, internal pressure and preforming low pressure. The following paper discusses to combine forming factors and expectation of manufacture problem by hydroforming of automotive radiator support member.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.15 no.1
• /
• pp.89-94
• /
• 2016

This study investigates the durability of the radiator and cooler of a laptop through a thermal analysis. In the result of this study, the maximum deformation happened at the part holding up the support stand at the radiator and cooler. The maximum thermal stress of the cooler was 60.939 Mpa, as low as that of the radiator. In addition, the safety factor of the cooler was 1.64 times as high as that of the radiator. The radiator of the laptop was less durable than the cooler. The result of this study could help with designing a laptop model with a durable radiator and cooler.

• Journal of Satellite, Information and Communications
• /
• v.10 no.3
• /
• pp.121-126
• /
• 2015

This paper proposes a novel reconfigurable microstrip antenna based on alternating a perturbation structure to achieve circular polarization diversity. The proposed antenna consists of an annular ring microstrip radiator for simultaneously loading stub and slot perturbations which support right- and left-handed circular polarization senses and two PIN diodes for choosing the operating polarization sense. By controlling the states of two PIN diodes between perturbing slot and stub at one diagonal corner of the radiator, reconfigurable circular polarization senses of the proposed antenna are successfully obtained and alternated. The proposed antenna has been theoretically analyzed and experimentally demonstrated at 2.4 GHz of S-band for satellite communication system. The simulation and measurement results of the proposed antenna show in good agreement with the reflection coefficients, axial-ratios, realized antenna gains, and radiation patterns.

• Journal of the Korean Home Economics Association
• /
• v.46 no.8
• /
• pp.55-72
• /
• 2008

The purpose of this study was to analyze the state of Goryoin housing in Uzbekistan and Korea. Using ethnographic methodologies, it was examined that 20 Goryoin households in Korea in relation to their usage of housing space firstly and also tried 20 Goryoin households in Uzbekistan with the same method. The following conclusion were established; 1). The majority of households in both areas preferred separated kitchen and living room areas. 2). Most households in both areas had a washing machine in bathroom and they regarded bathtub and the drain hole of the bathroom as very necessary. They all preferred separate bathroom and toilet areas in order to allow simultaneous use. 3). Their preferred seating style was chairs on sleeping and eating especially but they treated large family and guest without chairs in both areas. 4). All of them were took their shoes off and wore slippers at home usually and also had a preference for designated shoes space at the entrance to the house. 5) All of households in Uzbekistan and half of them in Korea had a carpet or mat in the bedroom or living room, both for keeping warm and aesthetic reasons. 6). The heating system of apartment in Uzbekistan was radiator and most of private houses had a modified Ondol with radiator but their preferred heating system was modified Ondol in both areas. 7). They all considered the living room as the most important housing space for family and guest in both areas.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.16 no.3
• /
• pp.28-35
• /
• 1979

In the microstrip antenna, insulator is filled only between its main radiator and the base conductor. In experiment, it is verified that the characteristic of microstrip antenna at 94 % of the operating frequency coincide with the characteristics of the Practical antenna, if its characteristics are analyged to the case that the entire space of the antenna is filled with the same insulator Experimental results support the theoretical validity.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.7 no.3
• /
• pp.56-61
• /
• 2008

Recently, although demands for an internal antenna applicable to DVB-H handhold terminals are increased, there are many difficulties in designing the antenna due to the long wavelength of $430{\sim}640mm$ and the wide bandwidth of $470MHz{\sim}702MHz$. Since the proposed DVB-H band antenna can be analyzed as an SDA (Supported structure Defined Antenna), it is designed by combination of the folded monopole radiator which has a wideband characteristics and the wing-type element which can reduce the resonant frequency effectively. The DVB-H band antenna has VSWR of 4 and obtains a good gain from -5 to 2 dBi, when it is built-in the mobile handset.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2009.05a
• /
• pp.187-190
• /
• 2009

Recently, automotive companies have invested in vehicle weight reduction and clean car development because of oil price rises and environmental problems. In particular, USA car makers have developed the vehicle spending 1 liter per 34km complying with PNGV(Partnership for a new generation of vehicle) and Europe car makers have developed the vehicle spending 3 liters per 100km. The USA government announced "The green car policy" in order to boost production of more fuel effective cars in 2009. According to the policy, it will be restricted to sell the car which spends more than 1 liter per 14.9km by 2020. To satisfy the current situations on automotive market, hydroforming technology has widely adapted vehicle structures such as engine cradle, chassis frame, A pillar, radiator support, etc. However, automotive companies have to consider formability and performance to improve and maximize the benefit from this technology in advance of detail design. The paper deals with one of the vehicle weight reduction methods using tube hydroforming technology and platform commonality in front suspension. FEA simulation is also introduced to evaluate hydro-formability and NVH performance at the beginning of design stage which is the best way to reduce the failure cost.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2013.10a
• /
• pp.119-123
• /
• 2013

We conduct the research for reducing aeroacoustic noise occurred when a vehicle operates in high speed situation without modifying the structural configuration such as deforming A-pillar's side curvature. We introduce PAU (Pneumatic Auxiliary Unit) which is a sort of air duct using intake air through radiator grill. According to our research, we can reduce overall noise levels around the surface of HSM (Hyundai Simplified Model). When a vehicleruns 100km/s, area-weighted acoustic power level (AWAPL) indicates 33dB without PAU. However with PAU, coverall AWAPL is decreased to 29dB which means we can improvesilentness approximately 12% compared to ordinary case. Moreover we conduct similar implementation to steering situation especially about yawing. In varioussituations, -10, 0, 10 degree of yawing, we observe 10% reduction in the upstream region of HSM but little increase in downstream region. It seems that inlet air overlap turbulent kinetic energy to surrounding flow. Even though downstream region's noise is louder than upstream region, overall AWAPL is still lower than conventional condition. We also apply this scheme to the real vehicle situation, then we get reasonable output which can support our research outputs.

• The Bulletin of The Korean Astronomical Society
• /
• v.35 no.1
• /
• pp.39.2-39.2
• /
• 2010

In this paper, I present the domestic development of near infrared camera systems for the ground telescope and the space satellite. These systems are the first infrared instruments made for astronomical observation in Korea. KASINICS (KASI Near Infrared Camera System) was developed to be installed on the 1.8m telescope of the Bohyunsan Optical Astronomy Observatory (BOAO) in Korea. KASINICS is equipped with a $512{\times}512$ InSb array enable L band observations as well as J, H, and Ks bands. The field-of-view of the array is $3.3'{\times}3.3'$ with a resolution of 0.39"/pixel. It employs an Offner relay optical system providing a cold stop to eliminate thermal background emission from the telescope structures. From the test observation, limiting magnitudes are J=17.6, H=17.5, Ks=16.1 and L(narrow)=10.0 mag at a signal-to-noise ratio of 10 in an integration time of 100 s. MIRIS (Multi-purpose InfraRed Imaging System) is the main payload of the STSAT-3 in Korea. MIRIS Space Observation Camera (SOC) covers the observation wavelength from $0.9{\mu}m$ to $2.0{\mu}m$ with a wide field of view $3.67^{\circ}{\times}3.67^{\circ}$. The PICNIC HgCdTe detector in a cold box is cooled down below 100K by a micro Stirling cooler of which cooling capacity is 220mW at 77K. MIRIS SOC adopts passive cooling technique to chill the telescope below 200K by pointing to the deep space (3K). The cooling mechanism employs a radiator, a Winston cone baffle, a thermal shield, MLI of 30 layers, and GFRP pipe support in the system. Opto-mechanical analysis was made in order to estimate and compensate possible stresses from the thermal contraction of mounting parts at cryogenic temperatures. Finite Element Analysis (FEA) of mechanical structure was also conducted to ensure safety and stability in launching environments and in orbit. MIRIS SOC will mainly perform the Galactic plane survey with narrow band filters (Pa $\alpha$ and Pa $\alpha$ continuum) and CIB (Cosmic Infrared Background) observation with wide band filters (I and H) driven by a cryogenic stepping motor.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.4
• /
• pp.2966-2970
• /
• 2015

Recently, solar light power generation is widely extended by support policy to regeneration energy. However generation efficiency is decreased when solar module maintain higher than certain point temperature. Therefore, it is need to maintenance under certain point temperature. An method of solving this problem, this paper is developed geothermal exchanger for efficiency improvement of solar cell module. Geothermal exchanger consisted of heat absorber of solar cell module and heat conductor and radiator. Heat of solar cell module is radiated in the earth by geothermal exchanger. An a result, geothermal exchanger is increased generation amount of solar cell module and experiment result showed costs to about 36% increment of generation power.