• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.27-30
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• 1991

With the recent development of high performance AC superconducting wire of very small ac loss and large current carrying capacity, the possibility of superconducting air core transformer is being studied. The air core transformer has merits of no iron loss, no insulation to the core and no harmonics. But the air core transformer has large exciting current and low magnetic coupling factor. To increase the coupling factor, the transformer of toroidal shape is proposed and designed. (10KVA, 110/220V) Compared with air core transformer of solenoidal shape, the performance is improved. The exciting current occupies about 22% of the rated current.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.81-82
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• 2008

본 논문은 국책사업으로 진행되는 한국형EMS(K-EMS : Korean Energy Management System)의 응용프로그램 중 하나인 TLF(Transmission Loss Factor)산정 프로그램에 대해 중요 알고리즘과 전반적인 기능에 대해서 기술하였다.

• Journal of the Korean Society of Radiology
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• v.18 no.3
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• pp.275-282
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• 2024

This study analyzed the factors that influence the development of gynecomastia by comparing blood test results and lifestyle between patients diagnosed with gynecomastia and normal control group. Independent sample t-test and chi-square tests were conducted to examine the mean differences among risk factors, and logistic regression analysis was used to calculate the relative risk ratio of various predictors influencing the development of gynecomastia. Age, HGB, HCT, TC, glucose, ALT, alcohol consumption, hair loss medication and medication for benign prostatic hyperplasia were identified as significant variables. Notably, the use of hair loss medication showed the highest univariate odds ratio of 15.79, while HGB decreased by a factor of 0.37. These results suggest that these could play a significant role in the onset of gynecomastia and could serve as foundational data for future diagnosis and management of the condition.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.35-40
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• 2024

In this paper, the design, implementation, and analysis of a device capable of transmitting and receiving millimeter-wave signals and performing channel sounding measurements in atmospheric conditions at distances of up to approximately 10km outdoors are presented. The device is expected to be instrumental in studying the propagation characteristics of millimeter-wave frequencies. Utilizing data such as received power levels and power delay profiles (PDPs), comparisons with predicted values using path loss, K-factor, and other propagation models are facilitated. The mobile transceiver unit, integrated onto a vehicle platform, allows for flexible adjustment of transmitter and receiver positions, while synchronization issues with distance are mitigated using a rubidium atomic clock. Furthermore, automatic boresight alignment using scanning techniques is employed to locate the main sector of the antenna.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.71-73
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• 2006

AC loss on variation of external magnetic field is a very important factor in development of power applications. In this paper, we measured and compared AC loss of hybrid-multi stacked wire made of the combination of 1G wires and 2G wires and uniform-multi-stacked wire made of one type of wires, 1G wires or 2G wires. Measurement was performed using by the linked-picked coil method. As results, as the number of wires increase, AC loss per unit volume of both stacked wires in low external magnetic field is reduced. Also AC loss of 2G slacked wire is higher than that of 1G wire. AC loss per unit length of 2G stacked wire is less than that of 1G stacked wire. And AC loss of hybrid-multi stacked wire made of the combination of 1G wires and 2G wires was between uniform-multi-stacked wire made of 1G wires and 2G wires.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.1
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• pp.15-24
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• 2010

Photovoltaic solar cells are all in the incident because they are not converted into electrical energy, high-efficiency solar cells in order to reduce the loss of elements must be. Significant factor in the loss of solar cells, optical loss and electrical loss can be divided into. Optical losses occur when the sun will be joined on the surface of the reflection, the shadow loss due to electrodes, and the losses are in the solar wavelengths. Commercialization is currently the most common solar cells on the front of the light incident on the electrode is formed. Therefore, the shadow caused by the electrode to cover the dead area of the sun, due to factors that hinder the absorption of sunlight which is shadowing them and conversion efficiency of solar cells is the inhibition factor. These barriers to eliminate the electrode linewidth reduces the shadowing to reduce, but simply of the electrode line width is reduced electrode area by reducing the series resistance elevates this because to improve the electrode Aspect ratio(height/width) to increase Ag development of paste is required. In this study, aspect ratio of screen-printing method to increase the electrode Ag paste composition of the binder for the characterization of rheology in the shadow of the electrode by reducing the optical loss of the photoelectric conversion efficiency of solar cells to boost the performance measures was. Properties and printability of the paste, the binder resin sintered characteristics that affect the thermal properties are excellent with a good screen printability acrylic resin, ethyl cellulose, using a resin were evaluated. Prepared paste rheology properties, was formed to evaluate the electrode conductivity and aspect ratio.

• 한국노년학
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• v.32 no.4
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• pp.1181-1197
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• 2012

This study aims to validate the Attitudes to Aging Questionnaire(AAQ), which was recently developed in foreign countries, for Korean elderly. Using a sample of 320 older individuals living in Seoul, Gyeonggi, Chungcheong areas, statistical analyses including item analysis, exploratory factor analysis, convergent validity analysis were attempted to AAQ which composed of three factors with 24 items. In result, the three factor model of AAQ(including psychosocial loss, physical change, and psychological growth) were reconstructed in which new three factors(psychological loss, social loss, and change and growth in body and mind) were confirmed and three items were deleted. Reliability and convergent validity of AAQ-21 were confirmed. AAQ-21 would be useful to researchers and practitioners working with older adults for systematically assessing the attitudes to aging of older individuals and thus contribute to development of social policies and welfare programs for the elderly.

• Journal of the Korean Society for Railway
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• v.11 no.2
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• pp.158-164
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• 2008

Abstract Infiltration of rainfall that may lead to reduce resistance force due to reduction of matric suction and to increase driving force due to increase of self weight makes the slope fail. There are many specifications to make slope stable based on factor of safety. Although result of slope stability analysis satisfy the specifications, slope failures triggered by rainfall are frequently occurred in reality because slope stability analysis cannot consider uncertainty of each soil properties. This is why conventional analysis has limitation and development of alternative method is needed. So it is suggested to adopt the reliability analysis rather than design based on factor of safety into designing safer structure. Through the evaluation of handicaps for the factor of safety based design, calculation of soil properties by site investigation, and reliability analysis considering distribution of each soil properties, distribution of failure probability in railway slope is obtained. Then, Risk assessment of slopes in Korean railway is executed from the results. Damage loss and incoming loss are considered as the loss. Using these results, it is possible to make proper countermeasure or efficient maintenance.

• BMB Reports
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• v.57 no.2
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• pp.98-103
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• 2024

The mammalian sirtuin family (SIRT1-SIRT7) has shown diverse biological roles in the regulation and maintenance of genome stability under genotoxic stress. SIRT7, one of the least studied sirtuin, has been demonstrated to be a key factor for DNA damage response (DDR). However, conflicting results have proposed that Sirt7 is an oncogenic factor to promote transformation in cancer cells. To address this inconsistency, we investigated properties of SIRT7 in hepatocellular carcinoma (HCC) regulation under DNA damage and found that loss of hepatic Sirt7 accelerated HCC progression. Specifically, the number, size, and volume of hepatic tumor colonies in diethylnitrosamine (DEN) injected Sirt7-deficient liver were markedly enhanced. Further, levels of HCC progression markers and pro-inflammatory cytokines were significantly elevated in the absence of hepatic Sirt7, unlike those in the control. In chromatin, SIRT7 was stabilized and colocalized to damage site by inhibiting the induction of γH2AX under DNA damage. Together, our findings suggest that SIRT7 is a crucial factor for DNA damage repair and that hepatic loss-of-Sirt7 can promote genomic instability and accelerate HCC development, unlike early studies describing that Sirt7 is an oncogenic factor.

• Korean Journal of Agricultural Science
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• v.47 no.3
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• pp.597-604
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• 2020

Exposure to heat stress (HS) has negative effects on pig production and health. Plasma concentrations of amino acids (AAs) can be used as indicators of HS. Therefore, this study was conducted to evaluate the effect of acute HS on feed intake, water drink, and plasma AAs in pigs. A total of 6 growing pigs (n = 6, 3 boars and 3 gilts) were raised in thermal neutral (TN; 25℃) conditions for the 5-d adaptation period as a control. After the adaptation, pigs were exposed to HS at 33℃ (HS33) for 24 h. All the pigs were fed the same diet formulated to meet or exceed predicted requirements during the whole experimental period. Blood samples were collected after the adaptation and heat treatment to verify the AAs. Measurements were the average daily feed intake (ADFI), average daily water intake (ADWI), water loss, tumor necrosis factor (TNF)-α, nitrate, total nitric oxide, and AAs in the plasma samples. Data were analyzed using the PROC GLM of SAS. HS33 had a lower ADFI (p < 0.05) and a tendency for an increased ADWI and water loss compared to TN. The level of TNF-α was significantly decreased (p < 0.05) in HS33. HS33 had a lower concentration of histidine and sarcosine compared to TN; however, there were no differences in the levels of nitrates and total nitric oxide. In conclusion, the results of this study show the differential effect of HS on the plasma concentration of AAs. We expect that the changed AAs could be potential indicators of HS.