• Annual Conference of KIPS
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• 2017.11a
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• pp.795-798
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• 2017

근래에 들어, 웨어러블 기기의 발전으로 사람의 움직임에 대한 측정이 손쉬워 지면서, 워킹, 러닝, 사이클링 등의 인간의 신체 활동 상태를 감지하여 더 효율적인 운동을 할 수 있도록 정보를 획득, 제공하려는 연구가 계속되고 있다. 본 연구에서는 웨어러블 기기중 하나인 스마트 인솔을 통해서 수집되는 가속도 정보와 압력 정보를 사용하여 운동시에 사람의 운동 자세를 감지하고 측정하는 시스템을 구현하였다. 사람이 헬스센터에서 수행하는 각각의 자세는 운동의 특성에 따라 시계열 신호의 표현 패턴이 다르게 나타나며 이 패턴을 통한 정확한 자세의 감지를 위해서 본 연구에서는 다양한 신호처리 알고리즘을 사용하였으며 이 경우 더 정확한 자세를 측정할 수 있음을 알 수 있었다. 따라서 본 연구에서는 정확한 자세의 감지를 위해 운동의 특징에 따라 알고리즘을 선택하여 시계열 정보를 처리 분석 하는 시스템을 제안하였으며 이를 통해 보다 정확하게 사람의 신체활동을 분석할 수 있었다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.39 no.4
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• pp.211-221
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• 2021

The Rabbit grass(Trifolium Repens, call it 'Clover') is a representative harmful plant of lawn, and it starts growing earlier than lawn, forming a water pipe on top of the lawn and hindering the photosynthesis and growth of the lawn. As a result, in competition between lawn and clover, clover territory spreads, but lawn is damaged and dried up. Damage to the affected lawn area will accelerate during the rainy season as well as during the plant's rear stage, spreading the area where soil is exposed. Therefore, the restoration of damaged lawn is causing psychological stress and a lot of economic burden. The purpose of this study is to distinguish clover which is a representative harmful plant on lawn, to identify the distribution of damaged areas due to the spread of clover, and to review of changes in vegetation before and after the eradication of clover. For this purpose, a time series analysis of three vegetation indices calculated based on images of convergence Drone with RGB(Red Green Blue) and BG-NIR(Near Infra Red)sensors was reviewed to identify the separation between lawn and clover for selective eradication, and the distribution of damaged lawn for recovery plan. In particular, examined timeseries changes in the ecology of clover before and after the weed-whacking by manual and brush cutter. And also, the method of distinguishing lawn from clover was explored during the mid-year period of growth of the two plants. This study shows that the time series analysis of the MGRVI(Modified Green-Red Vegetation Index), NDVI(Normalized Difference Vegetation Index), and MSAVI(Modified Soil Adjusted Vegetation Index) indices of drone-based RGB and BG-NIR images according to the growth characteristics between lawn and clover can confirm the availability of change trends after lawn damage and clover eradication.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.7-15
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• 2008

In this paper, the Chip-On-Flex (COF) assembly process using anisotropic conductive films (ACFs) was investigated and the reliability of COF assemblies using ACFs was evaluated. Thermo-mechanical properties of ACFs such as coefficient of thermal expansion (CTE), storage modulus (E'), and glass transition temperature $(T_g)$ were measured to investigate the effects of ACF material properties on the reliability of COF assemblies using ACFs. In addition, the bonding conditions for COF assemblies using ACFs such as time, temperature, and pressure were optimized. After the COF assemblies using ACFs were fabricated with optimized bonding conditions, reliability tests were then carried out. According to the reliability test results, COF assemblies using the ACF which had lower CTE and higher $T_g$ showed better thermal cycling reliability. Consequently, thermo-mechanical properties of ACFs, especially $T_g$, should be improved for high thermal cycling reliability of COF assemblies using ACFs for compact camera module (CCM) applications.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1599-1600
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• 2011

현재 사용되는 전력기기와 전기에너지로 구동되는 기기등은 환경 조화와 에너지 절약을 목표로 고전압 대용량화, 축소 소형화 및 고효율화가 진행되는 과정에 있다. 이런 기기들은 전위를 유지하기 위해서 전기절연기술이 필수적이다. 특히 전기절연재료의 역할이 중요해서 재료의 특성이 기기전체의 종합성능을 지배하기도 한다. 본 연구에서는 몰드 변압기의 절연수지로 사용되는 에폭시 복합체와 마이크로 $SiO_2$와 Ag 각 시편의 열팽창률과 유전 특성 및 온도에 따른 절연파괴강도를 측정하여 열적 특성 및 전기적 특성을 검토하고 분석한다.

• Journal of IKEEE
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• v.25 no.3
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• pp.528-533
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• 2021

This paper presents the PCB heat dissipation characteristics of high density DC-DC converter for electric vehicles. This paper also analyzes the heat dissipation structure of the high density DC-DC converter and optimizes the PCB heat dissipation design of the high density power system through thermal analysis simulation. Based on heat transfer theory, the thermal path of general electronic devices is analyzed and the thermal resistance equivalent circuit is modeled in this paper. Additionally, the thermal resistance equivalent circuit of the 500W synchronous buck converter, which is addressed in this paper, is modeled to present a structural heat dissipation path for better thermal performance. The validity of the proposed scheme is verified through the thermal analysis simulation results and experiments applying multi-surface heat dissipation structure to a 500[W](12[V], 41.67[A]) synchronous buck converter prototype with an input voltage 72[V].

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.210.1-210.1
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• 2013

ZnO는 태양전지의 투명전극 및 윈도우 물질로 그 동안 광범위하게 사용되어 왔다. 하지만 태양광의 효율 증가를 위하여서는 가시광 영역뿐만 아니라 자외선 및 적외선 영역을 이용할 필요가 있다. 또한 금속 산화물 반도체 나노 입자는 크기를 조절하여 흡수하는 태양광의 파장 영역을 조절할 수 있고 이를 이용하여 이종구조를 사지는 고효율의 태양전지를 구현할 수 있다. 본 연구에서는 3.4 eV의 에너지 밴드갭을 가지는 ZnO박막내에 밴드갭을 조절 할 수 있는 금속 산화물 나노입자를 삽입하여 광학적, 전기적 특성을 연구하였다. ZnO 박막을 증착하기 전 유리 및 사파이어 기판에 스퍼터를 사용하여 Pt금속전극을 형성한 이후, ZnO 박막을 $1{\times}10^{-10}$ Torr의 기본 진공도를 유지하는 초고진공 스퍼터를 사용하여 100 nm 두께로 증착 하였다. 금속 산화물 나노 입자를 제작 하기 위하여, ZnO 박막에 열증착 장비(thermal evaporator)를 사용하여 In 나노 입자를 10 nm 이하의 크기로 제작 하였다. 그 상부에 초고진공 스퍼터 와 열증착 장비를 사용하여 ZnO 박막 및 In 나노 입자를 순차적으로 증착하여 수백 nm 두께의 ZnO 박막을 제작한다. ZnO 박막 내부에 형성된 In 양자점은 ZnO 증착공정 중에 산화되어 $In_2O_3$ 의 산화물 나노 입자로 형성되며, 내부의 구조는 투과전자 현미경을 사용하여 확인 하였다. 제작된 금속 산화물 나노입자가 포함된 ZnO 박막의 광학적 특성을 photoluminescence, UV-Vis spectroscopy, ellipsometry를 통하여 확인 하였으며, solar simulator와 전류-전압 특정 장비를 사용하여 전기적 특성을 분석 하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.8
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• pp.597-604
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• 2013

A coupled thermomechanical analysis of composite structures in pyrolysis and ablation environments is performed. The pyrolysis and ablation models include the effects of mass loss, pore gas diffusion, endothermic reaction energy, surface recession, etc. The thermal and structural analysis interface is based upon a staggered coupling algorithm by using a commercial finite element code. The characteristics of the proposed method are investigated through numerical experiments with carbon/phenolic composites. The numerical studies are carried out to examine the surface recession rate by chemical and mechanical ablation. In addition, the effects of shrinkage or intumescence during the pyrolysis process are shown.

• Resources Recycling
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• v.16 no.4
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• pp.40-46
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• 2007

This research constructed property analysis for an high additional value construction materials. We try to utilize by the addition material of soil stabilizer. It was described to the material properties analysis of a sludge. A sample used 4 kinds of filtration cake which occurs by 4 companies and 3 kinds of sludge before filtration. ph of a sludge, a particle analysis and a scanning electron microscope observation were performed. We analyzed on the chemical ingredient by XRF, the phase by XRD, observed and analyzed the thermo-property of the sludge and the amount of the volatile constituent by TG-DTA.

• Journal of the Korean earth science society
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• v.22 no.1
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• pp.40-46
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• 2001

Heat exchange between the atmosphere and sea is produced using the data from two 3m discus buoy installed by KMA in 1996. The meteorological and oceanic characteristics at the Dukjukdo and Chilbaldo buoy for the period 1996 ${\sim}$ 2000 are discussed. Daily averaged sensible heat and latent heat flux at each site are estimated from bulk aerodynamic method using given data and analyzed. Quantitative analyses show SST indicates 1-year cycle like air temperature but has 1 month lag. Sea level pressure is lowest in July, humidity is higher from May to August, and wind speed has averaged value of 5 m/s and higher in autumn and winter. Sensible heat flux analyses present that strong heat loss from the sea occurs in autumn and winter and weak heat loss from atmosphere appears in spring and summer, and net sensible heat loss from the sea is found throughout the year. The ocean significantly releases latent heat into atmosphere from August to May but get a little latent heat from atmosphere in other months. Net latent heat loss from the sea is larger than net sensible heat loss except in January and February. Comparison with two sites suggests that the magnitude of heat flux and their fluctuation are generally stronger at Dukjukdo than at Chilbaldo. In case study, both sensible and latent heat flux is a little more at Chilbaldo in March 1998, but substantially stronger at Dukjukdo in November 1996.

• Journal of Sericultural and Entomological Science
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• v.46 no.1
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• pp.28-31
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• 2004

Bombyx mori silk fibroin/hyaluronic acid blend films were prepared by mixing aqueous solution of B. mori silk fibroin and hyaluronic acid. According to the FTIR spectra, no interaction between silk fibroin and hyaluronic acid was found. The conformation of silk fibroin in blend films was changed from random coil to $\beta$-sheet structure by treatment of EDC ethanol solution. Thermal degradation peak of silk fibroin and hyaluronic acid was also not altered by blending each other. The average swelling ratio of silk fibroin/hyaluronic acid blend films was 70. Therefore, silk fibroin/hyaluronic acid blend films might be one of possible wound dressing materials.