• 한국ITS학회 논문지
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• 제15권2호
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• pp.74-84
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• 2016

회전교차로(roundabouts) 설치이후 주변의 통행행태 변화로 인한 교통량 증가로 접근로별 교통류가 불균등(unbalanced flows) 해질 경우 접근로에서 회전교차로 내부로의 진입이 어려워져 교차로 전체의 효율성이 떨어지게 된다. 본 연구에서는 회전교차로 본래의 기능을 최대한 유지하면서 운영효율성을 높이기 위한 신호미터링 운영방안으로 동적 신호미터링 운영알고리즘을 제시하였고, 효과분석은 VISSIM의 COM Interface(Visual Basic Application) 기능을 활용하였다. 본 연구결과 인접한 두 진입로를 한 쌍(pair)으로 묶고 미터링진입로의 교통량이 통제진입로의 교통량 보다 작은 경우 실시간 Signal Metering운영 효과가 높은 것으로 분석되었다. 특히, 1차로형 4지 회전교차로를 기준으로 총 진입교통량이 1,600대/시일 때 차량 당 평균지체가 70.9~102.2초/대로 73.8~77.8% 감소하는 것으로 분석되었다.

• 국제지역연구
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• 제15권3호
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• pp.127-143
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• 2011

본 문의 목적은 환경문제에 관한 세계적인 담론과 의사소통이 증대함에 따라 비교정책학자들은 환경문제를 정책영역으로 결합하는 이론들을 발전시켜 나가는 데 상당한 기여를 해 왔다. 두 영역간의 연계에 대하여 기본적 이해와 전제에 대한 구축에 성공해왔다. 비교학자들은 환경문제를 국가를 초월하는 문제로 이해하고 있으나 실제 구축과 연결사례는 소수에 불과하다. 더군다나 이러한 학자들은 심오한 이론적 틀이 없이 단순하고 부분적인 경험적 고찰에 이르고 있다. 그러한 한계는 통합이론과 대규모 비교연구에 있어서는 부족함을 가져왔다. 본 연구는 정책채택에 대한 경험적 조사를 통하여 이러한 문제점에 대한 원인을 제시하고자 한다. 특히 120개국의 나라에 대한 회귀분석을 통하여 정책채택에 여부에 대한 영향을 미치는 요인을 검증하고자 하였다. 그 결과 국제적인 환경보호와 관련하여 국제환경기구의 존재여부가 정부의 정책채택의 규모에 영향력을 미치고 있으며 이러한 관심은 한국의 정책선택과정에 시사하는 바가 크다.

• 대한금속재료학회지
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• 제50권4호
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• pp.331-337
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• 2012

Electrical properties as a function of composition in silicon nitride ($SiN_x$) films grown at low temperatures ($<200^{\circ}C$) were studied for applications to photonic devices and thin film transistors. Both silicon-rich and nitrogen-rich compositions were successfully produced in final films by controlling the source gas mixing ratio, $R=[(N_2\;or\;NH_3)/SiH_4]$, and the RF plasma power. Depending on the film composition, the dielectric and optical properties of $SiN_x$ films varied substantially. Both the resistivity and breakdown field strength showed the maximum value at the stoichiometric composition (N/Si = 1.33), and degraded as the composition deviated to either side. The electrical properties degraded more rapidly when the composition shifted toward the silicon-rich side than toward the nitrogen-rich side. The composition shift from the silicon-rich side to the nitrogen-rich side accompanied the shift in the photoluminescence characteristic peak to a shorter wavelength, indicating an increase in the band gap. As long as the film composition is close to the stoichiometry, the breakdown field strength and the bulk resistivity showed adequate values for use as a gate dielectric layer down to $150^{\circ}C$ of the process temperature.

• Human Ecology Research
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• 제59권1호
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• pp.127-141
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• 2021

This study evaluates the financial status of Korean households using Household Financial Composite Index (HFCI) proposed in the preceding study. We analyzed 1,566 households with four persons aged 30-59 using raw data from the Korea Labor Panel Survey in 2016. The analysis results are as follows. First, HFCI was found to be 57.0 out of 100. Growth Index as one of three subindices was 11.1, which was significantly lower with 65.0 points for Status Index and 61.1 points for the Stability Index. Second, for households with male household owners, the overall financial score was 57.0, while that with female owners was almost similar with 57.2. HFCI was similar for the owner's age groups, but for Status Index, 58.5 for 30s, compared with 66.1 for 40s and 67.1 for 50s. The higher the education level of household owners, the better HFCI, with 53.2 high school graduates and 64.8 graduate graduates, showing a high gap of 11.6 points. HFCI for households living in owned housing was highest at 60.0, while that for rented housing was 40.7. Third, after controlling other effects, it was found that HFCI differed according to the level of education and ownership of housing living. Householder's gender was not found as a significant factor on HFCI. Status Index The 40s and 50s was higher than those in their 30s. Fourth, households were divided into three groups based on HFCI, named as risk, average and secure groups. HFCI for the risk group was 26.8, which was lower than 78.6 for the secure group, with a Status Index of 19.3. Households in their 50s and graduate school graduates were significantly included in the list of secure groups than others.

• 경제분석
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• 제17권4호
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• pp.30-51
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• 2011

무역자유화의 파급효과를 분석한 선행 연구의 대부분은 어떤 시점에 이루어진 무역자 유화가 해당연도 또는 그 다음연도와 같은 특정시점의 경제성과(economic performance)에만 영향을 미치는 것처럼 암묵적으로 가정하기 때문에 본질적으로 정태분석의 한계를 벗어나지 못한다. 이러한 선행연구와는 달리 본 연구는 무역자유화가 경제성과에 지속적으로 영향을 미칠 수 있는 동태적 실증분석모형을 설정하여 무역자유화의 누적효과(cumulative effects)를 분석한다. 또한 무역자유화의 파급효과에 대한 실증분석에서 제기되는 내생성(endogeneity)의 문제를 통제하기 위해 수준방정식과 차분방정식을 동시에 이용하는 동태적 패널 데이터 분석방법인 시스템 일반화적률법(system GMM)을 적용한다. 본 연구는 1988-2005년 기간의 한국 제조업을 대상으로 무역자유화의 정태 효과 및 동태적 누적효과를 추정하였는데, 무역자유화의 파급효과는 상당 기간 동안 지속되고, 동태적 누적효과는 정태효과에 비해 훨씬 더 크게 나타났다.

• The Korean Journal of Physiology and Pharmacology
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• 제28권1호
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• pp.93-103
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• 2024

Satellite glial cells (SGCs), a major type of glial cell in the autonomic ganglia, closely envelop the cell body and even the synaptic regions of a single neuron with a very narrow gap. This structurally unique organization suggests that autonomic neurons and SGCs may communicate reciprocally. Glial Ca²⁺ signaling is critical for controlling neural activity. Here, for the first time we identified the machinery of store-operated Ca²⁺ entry (SOCE) which is critical for cellular Ca²⁺ homeostasis in rat sympathetic ganglia under normal and pathological states. Quantitative realtime PCR and immunostaining analyses showed that Orai1 and stromal interaction molecules 1 (STIM1) proteins are the primary components of SOCE machinery in the sympathetic ganglia. When the internal Ca²⁺ stores were depleted in the absence of extracellular Ca²⁺, the number of plasmalemmal Orai1 puncta was increased in neurons and SGCs, suggesting activation of the Ca²⁺ entry channels. Intracellular Ca²⁺ imaging revealed that SOCE was present in SGCs and neurons; however, the magnitude of SOCE was much larger in the SGCs than in the neurons. The SOCE was significantly suppressed by GSK7975A, a selective Orai1 blocker, and Pyr6, a SOCE blocker. Lipopolysaccharide (LPS) upregulated the glial fibrillary acidic protein and Toll-like receptor 4 in the sympathetic ganglia. Importantly, LPS attenuated SOCE via downregulating Orai1 and STIM1 expression. In conclusion, sympathetic SGCs functionally express the SOCE machinery, which is indispensable for intracellular Ca²⁺ signaling. The SOCE is highly susceptible to inflammation, which may affect sympathetic neuronal activity and thereby autonomic output.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.115-116
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• 2012

The demand for flexible electronic systems such as wearable computers, E-paper, and flexible displays has increased due to their advantages of excellent portability, conformal contact with curved surfaces, light weight, and human friendly interfaces over present rigid electronic systems. This seminar introduces three recent progresses that can extend the application of high performance flexible inorganic electronics. The first part of this seminar will introduce a RRAM with a one transistor-one memristor (1T-1M) arrays on flexible substrates. Flexible memory is an essential part of electronics for data processing, storage, and radio frequency (RF) communication and thus a key element to realize such flexible electronic systems. Although several emerging memory technologies, including resistive switching memory, have been proposed, the cell-to-cell interference issue has to be overcome for flexible and high performance nonvolatile memory applications. The cell-to-cell interference between neighbouring memory cells occurs due to leakage current paths through adjacent low resistance state cells and induces not only unnecessary power consumption but also a misreading problem, a fatal obstacle in memory operation. To fabricate a fully functional flexible memory and prevent these unwanted effects, we integrated high performance flexible single crystal silicon transistors with an amorphous titanium oxide (a-TiO2) based memristor to control the logic state of memory. The $8{\times}8$ NOR type 1T-1M RRAM demonstrated the first random access memory operation on flexible substrates by controlling each memory unit cell independently. The second part of the seminar will discuss the flexible GaN LED on LCP substrates for implantable biosensor. Inorganic III-V light emitting diodes (LEDs) have superior characteristics, such as long-term stability, high efficiency, and strong brightness compared to conventional incandescent lamps and OLED. However, due to the brittle property of bulk inorganic semiconductor materials, III-V LED limits its applications in the field of high performance flexible electronics. This seminar introduces the first flexible and implantable GaN LED on plastic substrates that is transferred from bulk GaN on Si substrates. The superb properties of the flexible GaN thin film in terms of its wide band gap and high efficiency enable the dramatic extension of not only consumer electronic applications but also the biosensing scale. The flexible white LEDs are demonstrated for the feasibility of using a white light source for future flexible BLU devices. Finally a water-resist and a biocompatible PTFE-coated flexible LED biosensor can detect PSA at a detection limit of 1 ng/mL. These results show that the nitride-based flexible LED can be used as the future flexible display technology and a type of implantable LED biosensor for a therapy tool. The final part of this seminar will introduce a highly efficient and printable BaTiO3 thin film nanogenerator on plastic substrates. Energy harvesting technologies converting external biomechanical energy sources (such as heart beat, blood flow, muscle stretching and animal movements) into electrical energy is recently a highly demanding issue in the materials science community. Herein, we describe procedure suitable for generating and printing a lead-free microstructured BaTiO3 thin film nanogenerator on plastic substrates to overcome limitations appeared in conventional flexible ferroelectric devices. Flexible BaTiO3 thin film nanogenerator was fabricated and the piezoelectric properties and mechanically stability of ferroelectric devices were characterized. From the results, we demonstrate the highly efficient and stable performance of BaTiO3 thin film nanogenerator.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.189-189
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• 2012

Lead sulfide (PbS) nanocrystal quantum dots (NQDs) are promising materials for various optoelectronic devices, especially solar cells, because of their tunability of the optical band-gap controlled by adjusting the diameter of NQDs. PbS is a IV-VI semiconductor enabling infrared-absorption and it can be synthesized using solution process methods. A wide choice of the diameter of PbS NQDs is also a benefit to achieve the quantum confinement regime due to its large Bohr exciton radius (20 nm). To exploit these desirable properties, many research groups have intensively studied to apply for the photovoltaic devices. There are several essential requirements to fabricate the efficient NQDs-based solar cell. First of all, highly confined PbS QDs should be synthesized resulting in a narrow peak with a small full width-half maximum value at the first exciton transition observed in UV-Vis absorbance and photoluminescence spectra. In other words, the size-uniformity of NQDs ought to secure under 5%. Second, PbS NQDs should be assembled carefully in order to enhance the electronic coupling between adjacent NQDs by controlling the inter-QDs distance. Finally, appropriate structure for the photovoltaic device is the key issue to extract the photo-generated carriers from light-absorbing layer in solar cell. In this step, workfunction and Fermi energy difference could be precisely considered for Schottky and hetero junction device, respectively. In this presentation, we introduce the strategy to obtain high performance solar cell fabricated using PbS NQDs below the size of the Bohr radius. The PbS NQDs with various diameters were synthesized using methods established by Hines with a few modifications. PbS NQDs solids were assembled using layer-by-layer spin-coating method. Subsequent ligand-exchange was carried out using 1,2-ethanedithiol (EDT) to reduce inter-NQDs distance. Finally, Schottky junction solar cells were fabricated on ITO-coated glass and 150 nm-thick Al was deposited on the top of PbS NQDs solids as a top electrode using thermal evaporation technique. To evaluate the solar cell performance, current-voltage (I-V) measurement were performed under AM 1.5G solar spectrum at 1 sun intensity. As a result, we could achieve the power conversion efficiency of 3.33% at Schottky junction solar cell. This result indicates that high performance solar cell is successfully fabricated by optimizing the all steps as mentioned above in this work.

• 한국결정성장학회지
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• 제20권3호
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• pp.107-112
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• 2010

높은 광흡수 계수를$(1{\times}10^5cm^{-1})$ 가지는 CIGS는 Ga의 비율에 따라서 밴드갭을 조절할 수 있다는 장점을 지니고 있다. CIGS의 밴드갭은 Ga의 비율에 따라 $CuInSe_2$(Eg: 1.0 eV)에서 $CuGaSe_2$(Eg: 1.68 eV)까지의 범위에 존재하며, 태양전지에 서 이상적인 fill factor 모양을 가지도록 Ga의 비율을 높게 조성한다. CIGS 흡수층을 제작하는 방법에는 co-evaporator 방식이 가장 널리 사용되며 연구되고 있다. 이에 본 연구에서는 수평 형태의 hydride vapor transport (HVT)법을 고안하여 CIGS 나노 구조 및 에피성장을 시도하였다. HVT법은 $N_2$ 분위기에서 원료부의 CIGS 혼합물을 HCl과 반응시켜 염화물 기체상태로 변환 후 growth zone까지 이동하여 성장을 하는 방식이다. 성장기판은 c-$Al_2O_3$ 기판과 u-GaN을 사용하였다. 성장 후 field emission scanning electron microscopy(FE-SEM)과 energy dispersive spectrometer(EDS)를 이용하여 관찰하였다.

• 한국콘텐츠학회논문지
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• 제9권8호
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• pp.360-366
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• 2009

본 연구는 하체 비만 해소를 위한 효과적인 방법을 모색하고자 실시하였다. 여대생을 대상으로 아로마에센셜 오일을 이용한 경락마사지를 한 후 그 결과를 살펴보고자 하였다. 연구 대상은 본 연구에 참여를 희망하는 여대생을 중심으로 선발하였으며, 기간은 2008년 4월부터 6월까지로 8주였다. 선발군은 체성분 분석기로 체지방량과 체중을 측정하고 그 평균을 측정치로 이용하였으며, 표준과 과체중 각 4명씩, 비만 8명으로 분류하고 비만을 실험군으로, 표준과 과체증을 대조군으로 삼았다. 각 군은 아로마 에센션 오일 중 비만 해소에 효과가 있다고 선행연구에서 밝혀진 쥬니퍼 베리, 사이프러스, 파출리를 1:1:0.8의 비율(5방울(약 1ml),5방울, 4방울)로 혼합한 후 베이스오일로 30ml의 호호바 오일과 혼합하여 사용하였으며 선발군에 에센셜 오일 테스트를 거친 후 30분씩 하체 부위에 경락마사지를 실시하는 실험을 하였다. 실험을 통해 실험군과 대조군 모두 체중, 허벅지와 종아리 치수, 체지방률이 줄어드는 결과를 얻었다. 체지방률에서는 실험군과 대조군 모두 체지방률이 감소하였다. 다만 대조군과 실험군에서 각각 한 명씩이 체지방률이 약간 증가하였다. 혈액측정을 통한 연구 결과는 실험군과 대조군 모두 총콜레스테롤, LDL, 중성지방, 혈당 수치가 감소하였으나, HDL은 수치가 증가하는 결과를 얻었다. 이를 통해 여대생들의 잘못된 비만 관리가 이상 수치를 일으킬 수 있음을 발견할 수 있었으며 실험자의 각오와 인내심에 따라 결과치가 다름을 알 수 있었다.