• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.49-56
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• 2008

When the outdoor air temperature decreased less than the freezing temperature, frost forms at the surface of heat exchangers and it makes the performance degradation of a heat pump system. In this study, a heat pump system has been developed which has a refrigerant heating device as an auxiliarly heating equipment. To reduce power consumptions of the system, a liquid pump, rather than a compressor, was used to drive refrigerant in the heat pump cycle. Ratio of refrigerant mass flow between a refrigerant heating heat exchanger(GHX) and a outdoor plate heat exchanger(PHX) was varied and the system performance was measured and analyzed. As results, when the refrigerant flow rate to the GHX was decreased, the system performance is decreased due to heat absorption capability restriction of the GHX and small variation of the power consumption in the compressor. The effect on the evaporating and condensing pressure by the distribution ratio of the refrigerant to the each heat exchanger is small compare to the effect by the frequency change in the compressor. When the compressor was replaced by the liquid pump, the capacity of the system decreased a little, however the power consumption decrease approximately 80% compare with the power used in the compressor.

• Journal of Animal Science and Technology
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• v.66 no.1
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• pp.135-144
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• 2024

The objective of this study was to investigate the influence of feeding frequency on a sow's reproductive performance and stress response during gestation. A total of twenty multiparous sows (Yorkshire × Landrace) were used in a completely randomized design based on their parity, body weight (BW), and backfat thickness (BFT), and the sows were allotted to two different feeding systems: 1) once daily feeding (OF) and 2) twice daily feeding (TF) in corn-soybean meal based diets. The gestation diet was formulated to contain 3,265 kcal of metabolizable energy (ME) / kg, 12.90% of crude protein (CP), and 0.75 % of total lysine. The lactation diet was formulated to contain 3,265 kcal of ME / kg, 16.80% of CP, and 1.08% of total lysine and provided ad libitum during lactation. In gestation, sow BFT and BF changes were not affected by feeding frequency, but higher BW and BW gain from day 35 to 90 and day 35 to 110 were observed in OF sow (p < 0.10). In lactation, feeding frequency did not influence on BW, BW gain, BFT, BF changes, average daily feed intake, and wean-to-estrus interval. Also, there were no differences in litter size, litter weight and piglet weight in lactating sows. OF sows had higher (p < 0.05; p < 0.10) protein, solid-not-fat, and total solid concentrations in colostrum compared to TF sows, while OF sows had a lower (p < 0.05) lactose concentration in colostrum compared to TF sows. Sows in OF showed significantly lower average daily water consumption (ADWC) from day 35 to 110 of gestation (p < 0.05). While there were no significant differences in stereotypic behaviors and salivary cortisol levels during gestation between treatments, the OF sows showed less time spending on the activity at day 105 (p < 0.05). In conclusion, reduced feeding frequency increased BW gain during gestation, decreased activation time, and changed the colostrum composition. This information may contribute to the understanding of the physiological and behavioral change of gestating sows by manipulating feeding frequency.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2011.04a
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• pp.261-266
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• 2011

The purpose of this study was to identify the perception of residents on green home and their green residential life. For this study, a questionnaire survey was conducted and the items consisted of whether green home was perceived and how well green residential life was maintained in 6 types of environments. A total 118 responses of residents living in apartments of Seoul Metropolitan Area were used for data analysis. Using statistical program SPSS Win 18.0, frequency analysis, t-test, One-way ANOVA, and factor analysis was employed. The major findings were as follows: 1) slightly more than half of the respondents were aware of green home, and the vast majority were in favor of the green home policy; 2) most of the respondents carried out guidelines of green residential life, and in particular, green living on air environment was well done, followed by consumption, waste, energy, traffic and water; 3) the six kinds of environments were subcategorized by using factor analysis, and 3 to 5 factors were included in each category of environment. Also, it was found that age, educational level, employment status of respondents, housing tenure and duration were related to the degree of green residential life. In midst of global movement toward sustainability, environmentally friendly living is not optional but mandatory, so it's important to change each individual's value on the relation between people and environment and to facilitate more environmentally conscious behaviors.

• Journal of the Korean Society of Costume
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• v.50
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• pp.97-118
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• 2000

The purposes of the present research were (1) to investigate the sociological factors influencing the increase of ambivalence and the relationship between, the ambivalence and fashion change(2) to categorize sets of the ambivalence expressed for contemporary fashion and (3) to examine the frequency and the patterns of ambivalence presented for contemporary fashion. This research was conducted through in depth literature review and content analysis. Data was collected from 806 colored pictures presented on 'Collections' from 1972 to 1988. Eight types of clothing cues were incluede: look color texture decorative motifs of clothing collar sleeve and wearer's headdress/hair style and make-up. The results of this study were as follows: 1 The popularization of culture has been accelerated by mass production mass consumption and mass media. Since the 1980s postmodernism and poststructuralism have resulted in the breakdown of dualistic distinction. As the ambiguity of meaning in appearance increases the meaning is negotiated constantly for identity. 2. The most frequenctly expressed ambivalence in clothing was feminity/masculinity and tradition/modernity and wealth/poverty was the least. The number of ambivalent expression were the highest during 1990s. The rapid growth in ambivalence of tradition/modernity was found in 1970s feminity/masculinity in 1980s and modesty/immodesty in 1990s. Within a clothing style ambivalence was manifested through feminine look in white for beauty/ugliness feminine look mainly in yellow/red for wealty/poverty sexy look dominantly in black for modesty/immodesty androgynous look in black for feminity/masculinity and through ecology look most frequently in black for tradition/modernity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.10
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• pp.1861-1868
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• 2008

In this paper, Passive Telemerty RF Sensor System using Unscented Kalman Filter algorithm(UKF) is proposed. General Passive Telemerty RF Sensor System means that it should be "wireless", "implantable" and "batterless". Conventional Passive Telemerty RF Sensor System adopts Integrated Circuit type, but there are defects like complexity of structure and limit of large power consumption in some cases. In order to overcome these kinds of faults, Passive Telemetry RF Sensor System based on inductive coupling principle is proposed in this paper. Because passive components R, L, C have stray parameters in the range of high frequency such as about 200[KHz] used in this paper, Passive Telemetry RF Sensor System considering stray parameters has to be derived for accurate model identification. Proposed Passive Telemetry RF Sensor System is simple because it consists of R, L and C and measures the change of environment like pressure and humidity in the type of capacitive value. This system adopted UKF algorithm for estimation of this capacitive parameter included in nonlinear system like Passive Telemetry RF Sensor System. For the purpose of obtaining learning data pairs for UKF Algorithm, Phase Difference Detector and Amplitude Detector are proposed respectively which make it possible to get amplitude and phase between input and output voltage. Finally, it is verified that capacitive parameter of proposed Passive Telemetry RF Sensor System using UKF algorithm can be estimated in noisy environment efficiently.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.437-441
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• 2012

In this paper, we have designed and manufactured 10MHz power source for the application of short distance wireless power transmission. The designed power source consists of a DDS(direct digital synthesizer) signal generator, a buffer driver and a balanced power amplifier. Short range wireless power transmission is usually carried out by near-field inductive coupling between source and load. The distance variation between source and load gives rise to the change of load impedance of power amplifier, which has effect on the operation of power amplifier. To overcome this problem due to load variation of power amplifier, we have adopted the balanced power amplifier using the quadrature hybrid implemented by lumped capacitors and a mutually coupled coil. The experiment results show the above 40dBm output power, frequency range of 9 to 11MHz, and total DC power consumption of 36W.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.8
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• pp.901-906
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• 2006

In this paper, the power amplifier using active bias circuits for LDMOS(Lateral Diffused Metal Oxide Semiconductor) MRF-21180 is designed and fabricated. According to change the temperature, the gate voltage of LDMOS is controlled by the fabricated active bias circuits which is made of PNP transistor to suppress drain current. The driving amplifier using MRF-21125 and MRF-21060 is made to drive the LDMOS MRF-21180 power amplifier. The variation of current consumption in the fabricated 60 watt power amplifier has an excellent characteristics of less than 0.1 A, whereas a passive biasing circuit dissipates more than 0.5 A. The implemented power amplifier has the gain over 9 dB, the gain flatness of less than $\pm$0.1 dB and input and output return loss of less than -6 dB over the frequency range 2.11 $\sim$ 2.17 GHz. The DC operation point of this power amplifier at temperature variation 0 $^{\circ}C$ to 60 $^{\circ}C$ is fixed by active bias circuit.

• Nutrition Research and Practice
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• v.9 no.3
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• pp.304-312
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• 2015

BACKGROUND/OBJECTIVES: International students face dissimilar food environments, which could lead to changes in dietary behaviors and anthropometric characteristics between before and after migration. We sought to examine the risk factors, including dietary behaviors, acculturation, and demographic characteristics, related to overweight subjects residing in South Korea. SUBJECTS/METHODS: We conducted a cross-sectional study, collecting data from 142 Chinese international students (63 males, 79 females) in 2013. RESULTS: The mean age of the subjects was 25.4 years, and almost half of them immigrated to South Korea to earn a master's degree or doctoral degree (n = 70, 49.3%). Chinese international students showed an increase in skipping meals and eating speed, but a decrease in the frequency of fruit and vegetable consumption in South Korea compared to when they lived in China. We found a statistically significant increase in weight (69.4 ${\rightarrow}$ 73.9 kg) and BMI (22.4 ${\rightarrow}$ $23.8kg/m^2$) for male subjects (P < 0.001) but no change for female subjects. We also found that overweight subjects were more likely to be highly acculturated and male compared with normal-weight subjects. CONCLUSION: Among Chinese international students living in South Korea, male and more highly acculturated subjects are more vulnerable to weight gain. This study provides useful information to design tailored nutrition intervention programs for Chinese international students.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.4
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• pp.1-9
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• 2011

Forest area covers 64 % of the national land of Korea and the forest plays a pivotal role in the hydrological process such as flood, drought, runoff, infiltration, evapotranspiration, etc. In this study, soil moisture monitoring for conifer forest in experimental forest of Seoul National University has been conducted using FDR (Frequency Domain Reflection) for 6 different soil layers, 10, 20, 30, 60, 90 and 120 cm during 2009~2010, and precipitation data was collected from nearby AWS (Automatic Weather Station). Soil moisture monitoring data were used to estimate soil moisture recession constant (SMRC) for analyzing soil moisture recession characteristics. From the results, empirical soil moisture recession equations were estimated and validated to determine the feasibility of the result, and soil moisture contents of measured and calculated showed a similar tendency from April to November. Thus, the results can be applied for soil moisture estimation and provided the basic knowledge in forest soil moisture consumption. Nevertheless, this approach demonstrated applicability limitations during winter and early spring season due to freezing and melting of snow and ice causing peculiar change of soil moisture contents.

• Proceedings of the IEEK Conference
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• summer
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• pp.204-208
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• 2004

Embedded business will be expanded market more and more since customers seek more wearable and ubiquitous systems. Cellular telephones, PDAs, notebooks and portable multimedia devices could bring higher microprocessor revenues and more rewarding improvements in performance and functions. Increasing battery capacity is still creeping along the roadmap. Until a small practical fuel cell becomes available, microprocessor developers must come up with power-reduction methods. According to MPR 2003, the instruction and data caches of ARM920T processor consume $44\%$ of total processor power. The rest of it is split into the power consumptions of the integer core, memory management units, bus interface unit and other essential CPU circuitry. And the relationships among CPU, peripherals and caches may change in the future. The processor working on higher operating frequency will exact larger cache RAM and consume more energy. In this paper, we propose advanced low power trace cache which caches traces of the dynamic instruction stream, and reduces cache access times. And we evaluate the performance of the trace cache and estimate the power of the trace cache, which is compared with conventional cache.