• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.11a
• /
• pp.340-343
• /
• 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
• /
• v.14 no.1
• /
• pp.48-52
• /
• 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
• /
• v.42 no.1
• /
• pp.6-15
• /
• 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
• /
• v.3 no.2
• /
• pp.139-144
• /
• 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
• /
• v.8 no.2
• /
• pp.17-28
• /
• 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.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05a
• /
• pp.197-199
• /
• 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.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.35 no.2
• /
• pp.137-145
• /
• 1990

Six commercial rice varieties were cultivated at different locations in 1987 and 1988. Rice samples harvested from 8 to 20 locations for a variety each year were used to measure or observe grain appearance, amylose content and alkali digestibility, cooked rice texture using rheometer, gelatinization and viscosity of rice flour using amylograph, and eating Quality of cooked rice by sensory evaluation. Relationship between Quality characteristics showing large locational variation were analized to approach the long-term objective, rice grain Quality standardization. Percent white-center and white-belly grain of the same variety showed great variation between locations, but did not affect on 1000-grain weight, amylose content and alkali digestibility, amylogram and rheogram characteristics, and eating Quality of cooked rice. Positive correlationship were obtained between maximum viscosity and break down, and maximum viscosity and alkali digestibility. Set back was correlated negatively with maximum viscosity, break down and alkali digestibility. Rice samples having significantly lower values of maximum viscosity and break down and higher set back value at the same time showed higher ADV and lower texture palatability index (TPI) and viscousness/hardness ratio (Vi/H), and lower sensory evaluation score of cooked rice compared with those of rices having typically higher values of maximum viscosity and break down and lower set back value. When TPI, Vi/H and overall sensory eating score of cooked rices measured were divided into three categories, high, medium and low using deviation from locational mean value of a variety, many of rice samples having high TPI or high Vi/H showed medium or high in overall sensory eating score of cooked rice.

• Journal of Trauma and Injury
• /
• v.22 no.1
• /
• pp.29-36
• /
• 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.

• Transactions of the Korean hydrogen and new energy society
• /
• v.7 no.2
• /
• pp.121-128
• /
• 1996

A direct cooling equipment for hydrogen liquefaction has been developed and tested. A direct cooling equipment consists of a liquefaction vessel, a radiation shield, a cryostat and a GM refrigerator. The cool-down and warm-up characteristics of the liquefaction apparatus have been investigated in detail. It is found that the hydrogen starts to be liquefied in the liquefaction vessel after 45 minutes of cool-down. The cool-down and warm-up tests of helium gas are also performed. The cool-down and warm-up characteristics of helium gas are found to be very different from those of hydrogen gas, since helium is not liquefied under the present operating conditions. When the liquefaction vessel is evacuated, natural convection phenomena of charged gas in liquefaction vessel can be removed. It is seen that the cool-down time of liquefaction vessel is substantially increased in vacuum environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.2 s.93
• /
• pp.139-143
• /
• 2005

In this paper, we propose the design on LNA and Down-mixer for MB-OFDM UWB using $0.18\;{\mu}m$ CMOS. LNA, Down-mixer design result shows that it covers the frequency range ken 3 GHz to 5 GHz. The LNA gain is larger than 12.8 dB, and noise figure about 2.6 dB. Double balanced differential down-mixer is designed less than 2 dB gainflatness, and it has over 30 dB LO leakage, feedthrough characteristics.