• Journal of Biosystems Engineering
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• 제9권2호
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• pp.65-73
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• 1984

While most of researches on the performance of high temperature grain dryer have dealt mainly with improving dryer capacity and drying speed during the last twenty years, energy efficiency, in fact, has not been emphasized. Current fuel supplies and energy cost have shifted the emphasis to reducing the energy consumption for grain drying while maintaining dryer capacity and grain quality. Since the energy input for drying is relatively large, the recovery and reuse of at least part of the exhaust energy can significantly reduce the total energy consumption in existing drying systems. Unilization of exhaust heat in grain dryer either through direct recycling or by a thermal coupling in heat exchanger have been subject of a number of investigators. However, very seldom research in Korea has been done in this area. Three drying tests(non-recycling, 0.22 recycle ratio, and 0.76 recycle ratio)were performed to investigate the thermal efficiency and heat loss factors of continuous flow type dryer, and to analyze the effect of recycle ratio (weight of exhaust air recycled/total weight of input air) on the energy requriements for rough rice drying. The test results showed that when the exhaust air was not recycled, the energy lost from furnace was 15.3 percent of input fuel energy, and latent and sensible heat of exhaust air were 61.4 percent and 11.2 percent respectively. The heat which was required in raising grain temperature and stored in dryer was relatively small. As the recycle ratio of exhaust air was increased, the drying rate was suddenly decreased, and thermal efficiency of the kerosene burner was also decreased. Drying test with 0.76 recycle ratio resulted in 12.4% increase in fuel consumption, and 38.4% increase in electric power consumption as compared to the non-recycled drying test. Drying test of 0.22 recycle ratio resulted in 6.8% saving in total energy consumption, 8.0% reduction in fuel consumption, and 2.5% increase in electric power consumption as compared to the non-recycled drying test.

• Human Ecology Research
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• 제60권3호
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• pp.443-458
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• 2022

Generation MZ, a generic term for millennials and members of Generation Z, is an innovation-leading consumer group in the current market. This study aimed to examine the impact of the ethical consumption tendencies of millennials and Generation Z on the purchase intention of social enterprise fashion products. Data were collected from Generation MZ (15-40 years old) by quota sampling based on the demographic variables of gender, age, and region, respectively. Eight hundred responses were analyzed by descriptive statistics, factor analysis, t-test, and regressions using SPSS software. Three value factors (egoistic, altruistic, and biospheric) and three ethical consumption tendency factors (resource saving tendency, eco-friendly tendency, and consciousness of corporate responsibility) were determined by factor analyses. The results confirmed that women, who showed a higher ethical consumption tendency in all three factors, were more altruistic and biospheric than men. Furthermore, women portrayed a more favorable attitude and purchase intention towards fashion products of social enterprises. The results demonstrated that members of Generation Z were more altruistic and biospheric than millennials. Additionally, the attitude, purchase intention, and willingness to pay premium prices were higher in Generation Z members. It was confirmed that higher biospheric values correlated with greater values for the three ethical consumption tendency factors. The altruistic value affected both the resource saving tendency and eco-friendly trend, while the egoistic value had an effect on the resource saving tendency. Both attitude and purchase intention were positively influenced by all three of the ethical consumption tendency factors, and affected the willingness to pay premium prices. This was subsequently influenced by the resource saving tendency and consciousness of corporate responsibility. The results of this study contribute to understanding Generation MZ as a consumer group, and the establishment of marketing strategies for fashion companies.

• Hip & pelvis
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• 제35권2호
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• pp.63-72
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• 2023

The aim of this study was to conduct a meta-analysis of randomized controlled trials (RCTs) for comparison of the effectiveness of pericapsular nerve group (PENG) block with that of other analgesic techniques for reduction of postoperative pain and consumption of opioids after total hip arthroplasty (THA). A search of records in the PubMed, Embase, and Cochrane Library, and ClinicalTrials.gov databases was conducted in order to identify studies comparing the effect of the PENG block with that of other analgesics on reduction of postoperative pain and consumption of opioids after THA. Determination of eligibility was based on the PICOS (participants, intervention, comparator, outcomes, and study design) criteria as follows: (1) Participants: patients who underwent THA. (2) Intervention: patients who received a PENG block for management of postoperative pain. (3) Comparator: patients who received other analgesics. (4) Outcomes: numerical rating scale (NRS) score and opioid consumption during different periods. (5) Study design: clinical RCTs. Five RCTs were finally included in the current meta-analysis. Significantly lower postoperative opioid consumption at 24 hours after THA was observed in the group of patients who received the PENG block compared with the control group (standard mean difference=-0.36, 95% confidence interval -0.64 to -0.08). However, no significant reduction in NRS score at 12, 24, and 48 hours after surgery and opioid consumption at 48 hours after THA was observed. The PENG block showed better results for opioid consumption at 24 hours after THA compared with other analgesics.

• 한국전기전자재료학회논문지
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• 제23권8호
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• pp.593-600
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• 2010

In this paper, High brightness LED (light-emitting diodes) driver IC (integrated circuit) using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET (metal oxide semiconductor field effect transistor) from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. To confirm the functioning and characteristics of our proposed LED driver IC, we designed a buck converter. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses 1.0 ${\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre (Cadence) simulation.

• 전기학회논문지
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• 제61권4호
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• pp.612-616
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• 2012

This paper presents an active current regulator for LED driver IC. The proposed driver circuit is consists of DC-DC converter for supplying constant DC voltage to LED, active current regulator for compensating channel-to-channel current error from LED strings and feedback circuit for controlling duty ratio of the converter. The proposed active current regulator senses current of LED channels by equalizing both $V_{DS}$ and $V_{GS}$ at LED current control transistor. Because the proposed circuit directly measures the LED channel current without a sensing resistor and regulates all channel with same regulation loop, the power consumption and the current error are much small compared with previous works. The measured maximum efficiency of overall LED driver IC is approximately 94% and current error of LED channel-to-channel is under ${\pm}1.3%$. The proposed LED driver IC is fabricated Dongbu 0.35um BCD process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.9-9
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• 2010

In this paper, High Brightness LED driver IC using new current sensing circuit is proposed. This LED driver IC can provide a constant current with high current precision over a wide input voltage range. The proposed current-sensing circuit is composed of a cascode current sensor and a current comparator with only one reference voltage. This IC minimizes the voltage stress of the MOSFET from the maximum input voltage and has low power consumption and chip area by using simple-structured comparator and minimum bias current. The LED current ripple of the designed IC is in ${\pm}5%$ and a tolerance of the average LED current is lower than 2.43%. This shows much improved feature than the previous method. Also, protections for input voltage and operating temperature are designed to improve the reliability of the designed IC. Designed LED driver IC uses $1{\mu}m$ X-Fab. BiCMOS process parameters and electrical characteristics and functioning are verified by spectre(Cadence) simulation.

• 전기학회논문지
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• 제61권11호
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• pp.1752-1757
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• 2012

With the development in industry, power demand has increased rapidly. As consumption of power has increased, Demand for new power line and electric capacity has risen. However, in the event of fault, problems occur in extending the range of fault coverage and increasing fault current. In these reasons, protection devise is recognized as the prevention of an accident and fault current. This paper dealt with minimizing fault propagation and limiting fault current by adjusting fault current limiter (FCL) with fast interrupter. At this point, we compared and analyzed characteristics between non-inductive resistance and fault current which is limited by superconducting units. In normal state of the power system, power was supplied to the load, but when fault occurred, the interrupter was operated as CT which detected the over-current. Its operation made the limitation of fault current through a FCL. We concluded that the limiter using superconducting units was more efficient with the increase of power voltage. Superconducting fault current limiter with the fast interrupter prevented the spread of a fault, and improved reliability of power system.

• Transactions on Electrical and Electronic Materials
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• 제10권2호
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• pp.44-48
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• 2009

A simulation study of a 10-bit two-stage DAC was done by using a conventional current switch cell. The DAC adopts the segmented architecture in order to reduce the circuit complexity and the die area. The 10-bit CMOS DAC was designed in 2 blocks, a unary cell matrix for 6 MSBs and a binary weighted array for 4 LSBs, for fabrication in a 0.35-${\mu}m$ CMOS process. To cancel the accumulation of errors in each current cell, a symmetrical switching sequence is applied in the unary cell matrix for 6 MSBs. To ensure high-speed operation, a decoding circuit with one stage latch and a cascode current source were developed. Simulations show that the maximum power consumption of the 10-bit DAC is 74 mW with a sampling frequency of 100 MHz.

• 한국초전도ㆍ저온공학회논문지
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• 제3권1호
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• pp.35-39
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• 2001

The optimum cross-sectional area profile of gas-cooled high-temperature superconductor(HTS) current lead is analyzed to have minimum helium boil-off rate. The conventional constant area HTS lead has much higher helium consumption than the optimum HTS lead considered in this study. The optimum HTS lead has variable cross-sectional area to have constant satiety factor. An analytical formula of optimum shape of lead and temperature profile are obtained. For multi-stacking HTS current leads, the optimum tape lengths and minimum heat dissipation rate are also formulated. The developed formulations are applied to the Bi-2223 material, and the differences between constant area, constant safety-factor, and multi-stacking current leads are discussed.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.1077-1080
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• 1998

In this paper, a simple low-power current-mode CMOS wotage reference circuit is proposed. The reference circuit of enhancement-mode MOS transistors and resistors. Temperature compensation is made by adding a current component proportional to a thermal voltage to a current component proportional to a threshold voltage. The designed circuit has been simulated using a $0.65\mu\textrm{m}$ n-well CMOS process parameters. The simulation results show that the reference circuit has a temperature coefficient less than $7.8ppm/^{\circ}C$ and a power-supply(VDD) coefficient less than 0.079%/V for a temperature range from $-30^{\circ}C$ to $130^{\circ}C$ and a VDD range from 4.0V to 12V. The power consumption is 105㎼ for VDD=5V and $T=30^{\circ}C.$ The proposed reference circuit can be designed to generate a wide range of reference voltages owing to its current-mode operation.