• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.340-343
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• 2003

This paper presents characteristics of piezo transformer for AC-DC converter. This transformer uses transverse vibration mode and the origin of the structure was the ring dot type transformer. Because, the ring dot type transformers produce only step-up phenomenon, we made a multi-layered ring dot structure for a step-down output. The characteristics of the transformer were simulated by using the ANSYS. And frequency and voltage were measured by changing the load resistance and current. Frequencies that have the maximum output voltage and current were gradually increased, when the resistance were increased. Output voltage and current show a stable linearity according to the input voltage. The maximum output power was expected greater than 20 [W]. So, we expect that this type of multi-layered step-down ring dot transformer can be adopted for a small AC adapters.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권1호
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• pp.48-52
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• 2014

In this paper, scaling down characteristics of vertical channel phase random access memory are investigated with device simulator and finite element analysis simulator. Electrical properties of select transistor are obtained by device simulator and those of phase change material are obtained by finite element analysis simulator. From the fusion of both data, scaling properties of vertical channel phase change random access memory (VPCRAM) are considered with ITRS roadmap. Simulation of set reset current are carried out to analyze the feasibility of scaling down and compared with values in ITRS roadmap. Simulation results show that width and length ratio of the phase change material (PCM) is key parameter of scaling down in VPCRAM. Thermal simulation results provide the design guideline of VPCRAM. Optimization of phase change material in VPCRAM can be achieved by oxide sidewall process optimization.

• BMB Reports
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• 제42권1호
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• pp.6-15
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• 2009

The most common genetic disorder Down syndrome (DS) displays various developmental defects including mental retardation, learning and memory deficit, the early onset of Alzheimer's disease (AD), congenital heart disease, and craniofacial abnormalities. Those characteristics result from the extra-genes located in the specific region called 'Down syndrome critical region (DSCR)' in human chromosome 21. In this review, we summarized the recent findings of the DYRK1A and RCAN1 genes, which are located on DSCR and thought to be closely associated with the typical features of DS patients, and their implication to the pathogenesis of neural defects in DS. DYRK1A phosphorylates several transcriptional factors, such as CREB and NFAT, endocytic complex proteins, and AD-linked gene products. Meanwhile, RCAN1 is an endogenous inhibitor of calcineurin A, and its unbalanced activity is thought to cause major neuronal and/or non-neuronal malfunction in DS and AD. Interestingly, they both contribute to the learning and memory deficit, altered synaptic plasticity, impaired cell cycle regulation, and AD-like neuropathology in DS. By understanding their biochemical, functional and physiological roles, we hope to get important molecular basis of DS pathology, which would consequently lead to the basis to develop the possible therapeutic tools for the neural defects in DS.

• Journal of Power Electronics
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• 제3권2호
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• pp.139-144
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• 2003

In this paper, 11 and 13 layered step-down piezoelectric transformers were fabricated and their electrical characteristics have been analyzed for AC-adapter. When the voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, the output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. From the piezoelectric direct and converse effects, symbolic expressions between the electric inputs and outputs of the step-down piezoelectric transformer are derived with an equivalent circuit model. With those expressions, load and frequency characteristics are discussed through the simulations. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformers were measured under the different load and frequency conditions. First we measured resonant frequency from impedance curve and got equivalent impedance value of the piezoelectric transformer from admittance plot. It was shown from experiments that output voltage increase s and resonant frequency changes according to the various resistor loads. Output current decreases inversely proportional to the change of loads. Moreover, the measured output voltage and current are well matched with the simulated results obtained from the proposed equivalent circuit model. Furthermore, a new step-down piezoelectric transformer has been suggested to Increase the output power based on a simulation result having a driving piezoelectric vibrator polarized thickness direction.

• International Journal of Human Ecology
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• 제8권2호
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• pp.17-28
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• 2007

Using data from the 2001 American Housing Survey, the purpose of this study is to profile the economic and socio-demographic characteristics of baby boomers according to housing down payment sources and to identify determinants of housing down payment sources among baby boomers. Results of the multinomial logistic regression analysis indicated that household income, housing value, age, education, gender, marital status, race, and geographic region were all significant determinants of housing down payment sources among baby boomers. Identification of factors affecting the occurrence of borrowing for housing down payment would aid in the development of financial education programs for baby boomer households.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.197-199
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• 2011

To utilize the Top-Down construction method, it is required to analyse building area, floors, and soil conditions to choose the three basic elements of retaining wall, base column, and floor structure. The purpose of this research is to compare the methods of Top-Down with other construction methods. The research method is to analyse the project conditions of Top-Down project cases. The aim is to develop a method of selecting alternatives, considering construction characteristics, work schedule, supporting methods, foundation types.

• 한국작물학회지
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• 제35권2호
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• pp.137-145
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• 1990

국내에서 재배되고 있는 벼 6품종을 대상으로 품종별로 8-20 지역에서 1987년과 1988년에 생산된 쌀을 각각 수집하여 그들의 외관, 아밀로스함량 및 알칼리붕괴도, 아밀로그라프에 의한 쌀가루의 호화 및 점성특성과 레오메타를 이용한 밥알의 조직감(Texture)을 조사하고 관능검사법에 의한 식미평가를 실시하여 이들 상호간의 관계를 검토하였다. 1. 동일품종내에서는 재배지역에 따른 심복백미비율의 변이가 백미천립중, 쌀알의 아밀로스 함량과 알칼리붕괴도, 쌀가루의 아밀로그람특성, 밥알의 레오그람특성 및 식미와 각각 독립적으로 나타났다. 2. 재배지역에 따른 변이정도가 컸던 형질들간의 단순상관관계를 보면 아밀로그람특성 중 최고점도와 break down간에 정의 상관, 최고점도와 set back간, 그리고 set back과 break down간에는 부의 상관이 인정되었고 알칼리붕괴도와 break down간, 알칼리붕괴도와 최고점도간에는 정의 상관, 그리고 알칼리붕괴도와 set back간에는 부의 상관이 인정되었다. 3. 아밀로그람특성 중 최고점도와 break down 값이 낮았고 동시에 set back 값은 높았던 3지역 쌀은 최고점도와 break down 값이 높고 set back 값이 낮았던 3지역 쌀에 비하여 알칼리붕괴도는 높고, 레오그람특성 중 식미지수(TPI)와 점성/경도비율(Vi/H)은 낮았으며 관능검사법에 의한 종합식미에서도 낮은 점수를 받았다. 4. 레오메타로 조사한 점성/경도비율과 관능검사로 평가한 종합식미를 품종별 지역평균치보다 상급, 하급 그리고 평균치정도의 3등급으로만 나누어 두 형질간의 간계를 검토한 결과 점성/경도비율이 상급인 쌀은 종합식미가 평균치정도 또는 상급으로 판정받은 경우가 대부분이었다. 레오메타특성 중 식미지수와 종합식미와의 관계도 점성/경도비율에서와 비슷한 경향을 보였다.

• Journal of Trauma and Injury
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• 제22권1호
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• pp.29-36
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• 2009

Purpose: The purpose of this study was to analyze the characteristics and severity of wrist injuries in snowboarding. Methods: December 2005 to February 2008, Snowboarders who experienced wrist injures were included in this study. On the basis of the medical records and radiographic evaluation, the severity of distal radius fracture was classified according to the Arbeitsgemeinschaft fur Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) classification. Results: Most of the injured snowboarders were a either of the beginner (35 cases, 46.1%) or the intermediate (27 cases, 35.5%) level. The most common cause of injury in snowboarding was a slip down (60 cases, 78.9%). Comminuted and articular fractures classified as AO types A3, B, and C, which required surgical reduction, made up 42.3% of the distal radial fractures in snowboarders. When we analyzed the differences in severity between the educated and the non-educated groups, an A2 type injury in the AO classification was the most common type of injury in the educated group (20 cases, 38.5%), it means less severe fractures ocurred in the educated group (p=0.045). The most frequent injury mechanism of fractures was slip down (48 cases, 63.2%), and a slip down backwards was the dominant type of slip down (36 cases, 75.0%) (p=0.031). Conclusion: Among the snowboarders in this study who suffered self-down injury to the wrist, more fractures were associated with a backwards slip down than with a forward slip down due to over extension. For educated snowboarders the severity of fracture was lower than it was for uneducated snowboarders.

• 한국수소및신에너지학회논문집
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• 제7권2호
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• pp.121-128
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• 1996

수소액화를 위한 직접냉각장치를 개발하고, 이의 성능특성을 시험하였다. 직접냉각장치는 액화용기, 복사쉴드, 저온조와 GM냉동기 등으로 구성하였다. 개발된 액화장치의 cool-down 및 warm-up특성이 상세하게 규명되었다. 본 냉각장치에서 냉각이 시작된지 약 45분 후, 액화용기내의 수소가 액화되기 시작함을 확인하였다. 또한 동일한 실험을 기체헬륨에 대하여 수행하였으며, 기체헬륨은 주어진 작동조건에서 액화되지 않으므로 수소의 경우와는 다른 cool-down 및 warm-up 특성을 보였다. 충전된 기체의 자연대류현상의 영향을 고찰하기 위하여 액화용기내에 진공상태를 유지하면서 시험하였다. 이때 진공상태에서의 액화용기의 냉각시간은 현저히 증가함을 보였다.

• 한국전자파학회논문지
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• 제16권2호
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• pp.139-143
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• 2005

본 논문에서는 $CMOS\;0.18\;{\mu}m $ 공정을 이용하여 MB-OFDM UWB용 RF 수신기의 광대역 LNA와 Down-mixer를 설계하였다. 광대역 LNA는 $3\~5\;GHz$의 대역에서 전력이득은 $12.8\~15dB$, 잡음지수는 2.6 dB 이하, 그리고 입력 IP3는 4 GHz에서 -8 dBm의 특성을 나타내고, 입출력 반사손실은 10 dB 이하의 특성을 보인다. Down-mixer는 3개의 채널에서 2 dB 이하의 gain flatness를 나타내고, 변환이득은 $-2.9\~0.4dB$의 특성을 나타낸다. 또한 LO의 leakage와 feedthrough는 각각 30 dB 이상의 특성을 나타내도록 설계하였다.