• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.338-339
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• 2008

현재 PCB (Printed circuit board) 산업은 디스플레이, 모바일 시장의 수요 증가로 인해 활성화 되면서 다앙한 분야로 확대 되어가고 있다. 전자기기의 직접화, 고속파, 사용 주파수 영역의 증가로 인해 수십 GHz 영역에서도 활용이 가능한 소재 및 기판의 필요성이 대두되어 지고 있어 이에 대응할 수 있는 소재 개발도 다양해지고 있다. 본 논문에서는 GHz 영역에서 인쇄회로기판의 회로형태가 특성에 미치는 영향에 대해 연구하였다. 이를위해 패턴도금법과 에칭법으로 회로를 형성하였다. 패턴도금법으로 형성된 시편은 무전해 구리도금 공정을 거친 후 감광성 필름을 이용하여 전해 도금방법을 패턴을 형성하여 회로를 구현하였고, 에칭 패턴 시편은 FR4를 이용하여 동박접합과 도금 공정 후 마스크 패턴을 사용하여 노광, 현상, 에칭 공정을 거쳐 회로를 구성하였다. GHz영역에서 Transmission Line 특성을 분석하였으며 구리 패턴과 절연체사이의 계면형태가 특성에 영향을 주는 것을 확인할 수 있었다.

• Korean Journal of Optics and Photonics
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• v.19 no.5
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• pp.381-385
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• 2008

We have analyzed the effect of the substrate removal and packaging schemes on light output characteristics in InGaN/Sapphire LEDs. The removal of the sapphire substrate helps to dissipate the heat generated in the junction, but the advantage comes only with the detrimental effect of degrading the photon extraction efficiency. If the substrate-removed chip is attached to a metallic mount with good thermal conductivity, the maximum driving current is increased drastically, producing significantly increased light output and therefore compensating the photon extraction efficiency degradation. On a dielectric mount with a relatively poor thermal conductivity, however, it produces smaller light output, over most input current range, than the regular type of chips with the sapphire substrate remaining. Thus, for low power applications, the regular chips may be preferred over the substrate-removed chips, regardless of the chip mounts employed.

• Journal of the Microelectronics and Packaging Society
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• v.26 no.4
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• pp.149-156
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• 2019

A stretchable thermoelectric module consisting of 5 pairs of Bi₂Te₃-based hot-pressed p-n thermoelectric legs was processed by filling the module inside with polydimethylsiloxane (PDMS) and removing the top and bottom substrates. Its stretchable characteristics and power generation properties were measured. The integrity of the module was kept well even after 10 strain cycles ranging from 0 to 0.1. With increasing the tensile strain to 0.2, the module circuitry became open because of joint failure between Cu electrodes and thermoelectric legs. The stretchable thermoelectric module exhibited an open circuit voltage of 4.6 mV with a temperature difference of 2.2K across both ends of thermoelectric legs, and changes in its open circuit voltage were below 5% for tensile strains of 0~0.1. Being elongated for a strain of 0.1, it exhibited the maximum output power of 18.5 ㎼ with the temperature difference of 2.2K across its both ends.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.330-336
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• 2000

Effects of microstructure and indentation stress on fracture behavior of glass-infiltrated alumina composite for dental restorative application were investigated by the Hertzian and Vickers indentation method. Indentation stress-strain curve of glass-infiltrated alumina has showed the quasi-plastic behavior - deviation from linearity at high stress and the classical Hertzian cone crack, which could be confirmed the subsurface damage micrographs using bonded-interface specimen technique. The indentation stress-strain curves for the starting preforms are strongly dependent on porosity and microstructure of the preforms. On the other hand, the curves for the infiltrated composites are relatively insensitive to these factors. The failure of composite is originated at quasi-plastic deformation region. Damage and fracture behavior due to Hertzian stress field is theoretically examined, so that the indentation stress field plays a great role in material degradation. After Hertzian indentation annealing processing changes fracture behavior of alumina composite, so that stress field in material is healed through annealing.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.849-855
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• 2017

The development of a staged combustion cycle engine with higher perfomance is essential to provide higher transport capability of space launch vehicles. The combustor head of engine has a cone-shaped head and its manifold of combustor has a very complicated structure. The head and manifold have been manufactured by casting or machining methode. Metal 3D printing technologies are recently known as one of promising methods to improve manufacturing process for them because they are possible to over come limitations of the two methods. In this paper, a selective laser sintering method is used to make test materials and their physical properties are studying by changing its operation parameters to establish the better processing conditions. It is found that the 3D printing method is acceptable to manufacturing the head or manifold of combustor for staged combustion cycle engine.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1991.06a
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• pp.14-14
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• 1991

후두의 생리적 기능은 하기도를 보호하는 방어기능과 호흡기능 그리고 발성기능으로 대별할 수 있는데 이 가운데 계통발생적으로 가장 원시적이지만 중요한 기능은 하기도 방어기능으로 이는 다른 기능과 달리 전적으로 불수의적이고 반사적으로 이루어진다. 이 기능은 후두내 점막에 존재하는 촉각 수용체(tactile receptor)가 자극되면서 후두근육이 수축 반사를 일으켜 성문이 닫히는 성문폐쇄반사(glottic closure reflex)로서 다접합뇌간반사(polysynaptic brain stem response)이다. 현재까지 후두의 신경장애에서 그 부위나 정도 또는 신경재생 상태 등을 검사하는 방법으로 근전도검사가 주로 쓰여져 왔으나 그것이 주는 정보가 극히 제한되어 있다. 그러나 최근 청각뇌간유발반응과 같이 후두뇌간유발반응 이라 명명된 wave가 존재한다는 사실이 밝혀져 이에 대한 연구가 이루어지고 있어 이것이 임상에 쓰여질 수 있다면 현재 성문폐쇄반사의 소실이나 이상이 원인으로 사료되는 idiopathic laryngospasm, gastroesophageal reflux, spastic dysphonia, stuttering, sudden infant death syndrome과 같은 질환의 진단과 치료에 커다란 진전이 있을 것이다. 이에 저자들은 고양이 6마리를 이용하여 상후두신경을 전기적으로 자극하여 유발되는 반응을 far field recording을 이용 평균 가산법으로 그 wave를 측정하여 다음과 같은 결과를 얻었다. 1. 상후두신경자극(2㎃, stimuli frequency 3/s, Band filter 320-1000, 0.2 ㎳ duration)에 의한 반회신경에의 유발 반응을 기록하였고 그 잠복시간은 평균 8.2 ㎳ 였다. 2. 상후두신경을 자극하여 후두뇌간유발반응을 기록하였고 후두뇌간유발반응은 4개의 양 wave와 4개의 음 wave로 구성되었다. 3. 각 wave의 평균 잠복시간은 P1은 0.8㎳, P2는 2.3㎳, P3는 3.6㎳, P4는 4.3㎳였고 N1은 1.5㎳, N2 은 2.7㎳, N3는 3.9㎳, N4는 5.5㎳ 였다.

• Korean Journal of Construction Engineering and Management
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• v.18 no.5
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• pp.3-10
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• 2017

The HBS slab is a method in which a lightweight sieve is installed on top of the psc slab and two ribs of the neighboring psc slab are combined with ribs formed by the site concrete to act as a single member on the same axis. The purpose of this study is to implement the performance comparison with the existing method through the experimental study on the PSC slab method. In this study, the HBS slab was developed as a method to improve the limit of the existing method and the performance comparison with the existing method is tried to verify its superiority. The comparison of the structural performance with the existing method is carried out through the experimental study of the HBS slab, and the structural performance against the bending performance and shear and the bonding performance between the pc beam and the hbs slab are examined and compared with the existing method through the theoretical method.

• Journal of Life Science
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• v.16 no.1
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• pp.64-70
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• 2006

Starch gel electrophoresis was used to estimate genetic diversity and population structure of Pyrola fauriena H. Andr. in Korea. The percentage of polymorphic loci within enzymes was $57.1\%$. The values of genetic diversity at the species level and at the population were higher than average values for herbaceous with similar life history traits (Hes : 0.149; Hep = 0.134, respectively), whereas the extent of the population divergence was relatively low $(G_{ST}=0.082)$. $F_{IS}$, a measure of the deviation from random mating within the 12 populations, was 0.298. An indirect estimate of the number of migrants per, generation (Nm = 2.81) indicates that gene flow is moderate among Korean populations of the species. Analysis of fixation indices revealed a substantial heterozygosity deficiency in some populations and at some loci. This indicates that some populations sampled may have been substructured largely due to rhizotamous spread and decrease of population sizes.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.232-238
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• 1999

Single mode fiber optic interferometers using the Fabry-Perot configuration were embedded in a reinforced concrete structure. These interferometers investigated the character of phase shift and strain for internal loads. The 10 mm length of FFPI in the continuous length of single mode fiber (SMF) were produced with two pieces of SMF coated were $TiO_2$ dielectric film utilizing the fusion splicing technique. The fabricated fiber optic Fabry-Perot interferometer(FFPI) and the 6 mm length of steel bar were buried with specimen ($100{\times}100{\times}50\;mm^3$) which was made of concrete structure. The resin protects FFPI and fiber leads from squeezed concrete. Sensors at different point in the structure were multiplexed by TDM (Time Division Multiplexing) method and the deformation to the external loads at each point could be monitored simultaneously. The output signals were proportional to the external loads applied to the structure and the sensitivity of the sensors were $1.03^{\circ}/kg$ and $0.76^{\circ}/kg$ respectively.

• Journal of Korean Society of Steel Construction
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• v.20 no.4
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• pp.493-504
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• 2008

This paper deals with the experimental analysis of the flexural behaviour of encased composite beams with hollow core slabs and channels. The shear force between steel beams and hollow core slabs are transferred by channels. Three full-scale specimens were constructed and tested with different steel beam heights, which were compared with those of previous studies. Based on observation of the experiments, the encased composite beams exhibited full shear connection behaviour without any other shear connectors due to their inherent mechanical and chemical bond stress. Experimental results show a behaviour similar to steel-concrete composite beams with classical connectors: elastic and yield domains, great ductility, flexural failure mode (plastic hinge), low relative movement at steel-concrete interface and all specimens failed in a very ductile manner. Consequently, this study enables the validation of the proposed connection device under static loading and shows that it meets modern structural requirements.