• Journal of Power Electronics
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• 제15권4호
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• pp.1131-1138
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• 2015

This study presents an input-powered high-efficiency interface circuit for energy harvesting systems, and introduces a zero standby power design to reduce power consumption significantly while removing the external power supply. This interface circuit is composed of two stages. The first stage voltage doubler uses a positive feedback control loop to improve considerably the conversion speed and efficiency, and boost the output voltage. The second stage active diode adopts a common-grid operational amplifier (op-amp) to remove the influence of offset voltage in the traditional comparator, which eliminates leakage current and broadens bandwidth with low power consumption. The system supplies itself with the harvested energy, which enables it to enter the zero standby mode near the zero crossing points of the input current. Thereafter, high system efficiency and stability are achieved, which saves power consumption. The validity and feasibility of this design is verified by the simulation results based on the 65 nm CMOS process. The minimum input voltage is down to 0.3 V, the maximum voltage efficiency is 99.6% with a DC output current of 75.6 μA, the maximum power efficiency is 98.2% with a DC output current of 40.4 μA, and the maximum output power is 60.48 μW. The power loss of the entire interface circuit is only 18.65 μW, among which, the op-amp consumes only 2.65 μW.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6965-6969
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• 2013

Background: Tobacco consumption has been identified as the single biggest cause of inequality in morbidity and mortality. Understanding pattern of socioeconomic equalities in tobacco consumption in India will help in designing targeted public health control measures. Materials and Methods: Nationally representative data from the India Global Adult Tobacco Survey (GATS) conducted in 2009-2010 was analyzed. The survey provided information on 69,030 respondents aged 15 years and above. Data were analyzed according to regions for estimating prevalence of current tobacco consumption (both smoking and smokeless) across wealth quintiles. Multiple logistic regression analysis predicted the impact of socioeconomic determinants on both forms of current tobacco consumption adjusting for other socio-demographic variables. Results: Trends of smoking and smokeless tobacco consumption across wealth quintiles were significant in different regions of India. Higher prevalence of smoking and smokeless tobacco consumption was observed in the medium wealth quintiles. Risk of tobacco consumption among the poorest compared to the richest quintile was 1.6 times higher for smoking and 3.1 times higher for smokeless forms. Declining odds ratios of both forms of tobacco consumption with rising education were visible across regions. Poverty was a strong predictor in north and south Indian region for smoking and in all regions for smokeless tobacco use. Conclusions: Poverty and poor education are strong risk factors for both forms of tobacco consumption in India. Public health policies, therefore, need to be targeted towards the poor and uneducated.

• Nutrition Research and Practice
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• 제13권5호
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• pp.425-433
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• 2019

BACKGROUND/OBJECTIVES: The International Agency for Research on Cancer defined alcohol beverages and acetaldehyde derived from alcoholic beverages as a Group 1 carcinogen to humans. However, the association between alcohol consumption and gastric cancer risk has been controversial in Korean. We assessed the relationship between alcohol consumption and gastric cancer risk in Korea through a case-control study. SUBJECTS/METHODS: From 2 hospitals, a total of 316 cases with gastric cancer (208 men, 108 women) were selected and matched to 316 controls by sex and age (${\pm}5years$) during the same duration. The current status, frequency, and amount of alcohol consumption for a year three years ago were assessed by trained interviewers. RESULTS: Alcohol consumption status and frequency did not show any significant association with gastric cancer risk. However, high alcohol consumption (${\geq}20g/day$ for women or ${\geq}40g/day$ for men) significantly increased the risk of gastric cancer (odds ratio (OR) 1.73; 95% confidence interval (CI) 1.05-2.85). Gastric cancer risk was strongly positively associated with alcohol consumption of ${\geq}20g/day$, especially in women (OR 5.62; 95% CI 1.32-23.81). CONCLUSION: The results from this study suggest that excessive alcohol consumption rather than the current status or frequency of alcohol consumption contributes to the increased risk of gastric cancer, especially in women.

• 한국전자통신학회논문지
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• 제11권7호
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• pp.659-664
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• 2016

본 논문에서는 고속 동작과 저전력 동작을 요구하는 디지털 회로 시스템에 사용될 수 있는 Current-mode FIR Filter를 위한 OTA(:Operational Trans-conductance Amplifier) 회로를 제안한다. Current-mode 신호처리는 동작 주파수와 상관없이 일정한 전력을 유지하는 특징이 있기 때문에 고속 동작을 요구하는 디지털 회로 시스템의 저전력 동작에 매우 유용한 회로설계 기술이라고 할 수 있다. 0.35um CMOS 공정을 이용한 시뮬레이션 결과, Vdd=2V에서 전원 전압의 50%에 해당하는 약 1V의 Dynamic Range를 확보하였으며, 약 0~200uA의 출력전류를 확인하였다. 설계한 OTA 회로의 전력은 약 21uW가 계산되었으며, Active Layout 면적은 $71um{\times}166um$ 사이즈로 집적화에 유리할 것으로 기대된다.

• 전자공학회논문지D
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• 제36D권5호
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• pp.1-10
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• 1999

저전력으로 동작하고 24리드 SSOP에 실장할 수 있는 2.4 GHz 송수신 MMIC를 1.0㎛ 이온주입 MESFET공정으로 제작하였다. 이MMIC는 송신모드일 때 2.44 GHz에서 3.9 mA의 전류를 소모하였으며 이때 변환이득은 7.5㏈, 출력 IP3는 -3.5 ㏈, 잡음지수는 3.9㏈이었다. 수신모드일 때는 소모전류 2.0mA로 전압검출도 6.5 mV/μW를 나타내었다. 그동안 발표된 다른 MMIC가 우수한 성능을 가지고 있음을 알 수 있었으며 2.4 GHz의 ISM 대역에서 간단한 방식의 무선랜, WLL, RFID 등으로 응용될 것이 기대된다.

• Membrane and Water Treatment
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• 제1권1호
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• pp.13-37
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• 2010

The performance of an electrodialyzer for concentrating seawater is predicted by means of a computer simulation, which includes the following five steps; Step 1 mass transport; Step 2 current density distribution; Step 3 cell voltage; Step 4 NaCl concentration in a concentrated solution and energy consumption; Step 5 limiting current density. The program is developed on the basis of the following assumption; (1) Solution leakage and electric current leakage in an electrodialyzer are negligible. (2) Direct current electric resistance of a membrane includes the electric resistance of a boundary layer formed on the desalting surface of the membrane due to concentration polarization. (3) Frequency distribution of solution velocity ratio in desalting cells is equated by the normal distribution. (4) Current density i at x distant from the inlets of desalting cells is approximated by the quadratic equation. (5) Voltage difference between the electrodes at the entrance of desalting cells is equal to the value at the exits. (6) Limiting current density of an electrodialyzer is defined as average current density applied to an electrodialyzer when current density reaches the limit of an ion exchange membrane at the outlet of a desalting cell in which linear velocity and electrolyte concentration are the least. (7) Concentrated solutions are extracted from concentrating cells to the outside of the process. The validity of the computer simulation model is demonstrated by comparing the computed results with the performance of electrodialyzers operating in salt-manufacturing plants. The model makes it possible to discuss optimum specifications and operating conditions of a practical-scale electrodialyzer.

• 설비공학논문집
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• 제23권5호
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• pp.342-348
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• 2011

This study analyzes the current and after retrofit energy consumption of lighting and cooling system of a superstore in Seoul. Energy consumption data were measured and collected with a measurement system. Annual energy consumption was calculated using TRNSYS program. After replacing lighting and chiller with higher efficiencies, annual TOE consumption decreased from 1,066 before retrofit to 832 after retrofit, saving 234 TOE (22%) in total. Similarly, total annual $TCO_2$ consumption decreased from 2,214 to 1,721, reducing 493 $TCO_2$ (22%) during this pilot study.

• 한국유기농업학회지
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• 제20권1호
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• pp.1-19
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• 2012

The purpose of this study is to analyze consumption of homemade organically processed food (HOPF), and to derive directions for consumption promotion of HOPF. A survey was conducted for quantitative analysis regarding consumption. This study used an Ordinal Logistic Regression Model to derive more significant results in analyzing factors of consumption. The findings was that younger consumers with high income are more likely to purchase HOPF. And those consumers with high price and quality contentment are more likely to purchase HOPF. And contentment with certification institutions and improvement of health have a significant positive relationship with consumption. Consumers were found to pay 51 percent more for HOPF than for non-HOPF products. This level show that the current level of price premium for HOPF is 51 percent higher than their desired level. In order to reduce the price premium for HOPF, effective policy programs should be developed. A targeted market strategy to sell HOPF to younger consumers with high income is needed to boost consumption. A strict certification management system should be established to enhance consumer reliability in HOPF.

• 한국항만경제학회지
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• 제25권2호
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• pp.231-246
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• 2009

정기용선(Time Charter)은 운항선사가 자본력이 약하거나, 일시적으로 선복이 부족할 경우, 일정기간 타선사의 선박을 빌려 운항하려 할 때 이용되는 방식이다. 정기용선기간 동안 용선주의 선박운항에 따른 이익관계는 선속유지 및 연료유 사용량에 크게 의존하고 있고, 이에 대한 분쟁이 발생하게 됨을 볼 수 있다. 분쟁의 주요 원인은 용선계약서상에 선속 및 연료유 사용에 대한 제약 조항인 약(about), 좋은 날씨(good weather), 조용한 바다(smooth water), 대양해류(ocean current), 특정된 선속 및 연료유 사용에 대해 담보하지 않은 경우(without guarantee) 등이 있다. 판례와 중재판정에서는 좋은 날씨(good weather)를 풍력계급표(Beaufort Scale)상 4라 하였으며, 이 때 너울의 높이는 1.25m 이내로 정의하고 있다. 해류는 역조의 영향을 배제한다는 조항(No Adverse Current)이 있다면 좋은 날씨에 항해를 했다하더라도 역조구간은 제외되어야 한다. 정기용선계약서에서 사용되는 약(about)은 선속에 대하여는 특정된 선속에 0.5kt의 감속과 연료유 사용량에서는 5%의 증감을 적용한다고 했다. 부담보(Without Guarantee)의 경우 선주는 계약의 신의성실의 원칙에 의해 면책특권을 향유할 수 있지만, 재용선을 줄 때는 특권을 향유할 수 없다는 것이 일반적이다. 용선된 선박의 선속 저하로 발생한 시간손실과 절감된 연료유와 상계는 영국법상 정기용선계약서에 특정하지 않을 경우 원칙적으로 인정을 하고 있다. 좋은 기상에 대한 기상회사의 항해분석 보고서와 항해일지가 일치하지 않을 경우에는 정기용선계약서에 항해일지가 우선한다는 특정이 없을 경우 기상회사의 보고서가 우선하여 적용되며, 정당한 사유가 없는 한 선주의 대리인인 선장은 단거리 항로를 항해해야할 의무가 있다는 것이 Hill Harmony 판례로 확인되었다. 정기용선계약서상에 사용하는 이들 문구나 조항의 정의를 명확히 정의하고 명기하여야 분쟁을 예방할 수 있다.

• 한국전자파학회논문지
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• 제27권2호
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• pp.212-215
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• 2016

본 논문에서는 $0.18{\mu}m$ CMOS 공정을 사용하여 5.08 GHz에서 동작하는 링 전압 제어 발진기(Ring Voltage Controlled Oscillator, Ring VCO)를 제작하였다. Ring VCO는 3단 구조로 각 단의 트랜지스터 크기 비율을 다르게 하여 전류 변화에 따른 소모 전력이 달라짐을 확인하였다. Core의 양단 위, 아래에는 Current Mirror로 전류를 제어하도록 구성하였고, 주파수 조절을 위해 제어 전압을 추가하였다. Ring VCO 측정 결과, 주파수 범위는 65.5 %(1.88~5.45 GHz), 출력 전력 -0.30 dBm, 5.08 GHz 중심주파수에서 -87.50 dBc/Hz @1 MHz의 위상잡음을 갖는다. 또한, 2.4 V 전원에서 31.2 mW 소모 전력을 확인하였다.