• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.2
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• pp.124-132
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• 1987

In this paper, a new Open and Closed Loop Alternation(OCLA) frequency synthesizer is developed to eliminate a frequency error occurring in the transition state of a frequency hopping. This frequency synthesizer consists of a phase comparator(PC), two low pass filters(LPF), two voltage controlled oscillators(VCO), switching elements, a programmable divider and frequency hopping controller, and the stabilized output frequency can be obtained by switching performance. In addigion, it can be found that the characteristic of its circuit construction makes it easy to attach an external circuitry to the open loop.

• The Safety technology
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• no.160
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• pp.12-14
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• 2011

대전 서남부 지역 주거환경 개선을 위해 도안신도시가 한창 개발주인 가운데 일부 아파트는 벌써 입주가 완료되면서 신도시로서의 면모가 차츰 갖춰지고 있다. 이 시기에 맞춰 교통의 흐름을 원활히 하기 위한 터널공사와 교야 공사도 함께 분주히 진행되고 있다. 오늘 찾은 현장이 바로 터널공사와 교량고사를 담당하고 있는 계룡건설 대전도안지구 동서대로 건설현장(현장소장 이기욱)이다. 총 연장 1.82km의 편도 4차선터널과 3백여미터의 교량 건설이 한창인 이 곳은 중장비가 연신 들락거리는 가운데 각종 차량과 인력이 유기적으로 들어가며 안전시공, 무재해 시공에 연염이 없다. "신바람 나게 즐기면서 재미있게" 일을 하고 있는 계룡건설 대전도안지구 동서대로 건설현장(이하 동서대로 현장)을 찾아 이들만의 안전 이야기를 들어 봤다.

• The Safety technology
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• no.189
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• pp.24-26
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• 2013

안성시시설관리공단은 2000년 7월 1일 안성시가 자본금 전액을 출자해 설립한 지방 공기업이다. 이곳은 안성 시민들의 편안한 문화생활을 돕기 위해 시민회관, 문예회관, 종합운동장, 실내체육관, 국제정구장, 국민체육센터, 청소년문화의 집 등 공공시설물을 관리 운영을 하는 것은 물론 생활폐기물 및 재활용품 수거, 종량제봉투 판매사업을 통해 쾌적한 도시환경을 조성하고 있다. 이처럼 시민의 편의와 복리증진을 위한 여러 업무를 수행하고 있는 만큼 공단의 인력 구성 역시 각종 시설물을 관리하는 전문가에서부터 중장비 기사, 프로그램 강사, 환경미화를 담당하는 미화원에 이르기까지 매우 다양하다. 때문에 공단은 사전에 업무별로 위험요소를 분석하고 근로자들의 안전사고를 예방하려는 움직임으로 더욱 분주하다. 사고 규모를 떠나서 재해가 발생하면 피해 당사자는 물론 공단, 나아가서는 안성 시민에게까지 피해를 입힐 수 있기 때문이다. 안전을 최우선으로 삼고 최상의 공공서비스를 제공하고 있는 안성시시설관리공단을 찾아가봤다.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.11a
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• pp.1456-1459
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• 2011

최근 한국의 핸드폰 보급률이 95%가 넘으면서, 스마트폰의 사용자수 역시 활발하게 증가하고 있다. 또한 여성의 사회 활동도 꾸준히 증가하고 있다. 분주한 생활 속에서 식품관리의 편리성을 증대하고, 음식물 낭비를 줄이기 위하여 스마트폰으로 가정의 냉장고 식품을 한눈에 관리 할 수 있는 식품관리시스템을 개발하였다. 안드로이드 SDK 기반으로 가정의 냉장고 음식 위치, 유통기한 및 알람을 제공하고, 보유한 음식물을 기반으로 가능한 요리 방법을 검색하는 등의 기능을 제공한다. 본 논문에서는 이 어플리케이션에 대하여 설명한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.511-514
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• 2020

그동안 4차 산업혁명에 따른 신산업 성장이나 데이터 활용에 걸림돌이 되고 있다는 비판을 받아온 이른바 데이터 3법이 개정됨에 따라 데이터 경제 시대를 본격적으로 맞이하는 마중물이 되리라는 기대가 커지고 있다. 이에 따라 금융권 등 민간영역은 물론이고 중앙부처 등 공공영역에서도 데이터 3법의 개정에 따른 대응 방안을 모색하는 등 분주히 준비하는 상황이다. 따라서 농업분야에서도 데이터 경제 활성화를 목표로 데이터 3법 개정에 따른 대응 방안을 연구하고자 한다.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.23-28
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• 1983

To study ecological characteristics of Eleocharis kuroguwai occuring in Korea its propagules were collected from 6 locations from the northern part to the southern part of Korea (Chuncheon, Suweon, Iri, Jeonju, Gwangiu and Milyang) in 1981, cultured and replanted 3 times (May 20, June 5, June 20) in 1982. They flowered from August 5 to August 27 when they were planted on May 20, and from August 20 to August 27 when they were planted on Tune 20. Plant height, number of tillers and top fresh weight/$m^2$ were 50-90cm, 500-875, and 175-750g, respectively when they were planted on May 20, and 40-70cm, 250-625, 325-625g, respectively when they were planted on June 20. Number of tubers per plant were 0.98-1.98 when they were planted on May 20, and 1.81-2.87 when they were planted on June 20. Eleocharis kuroguwai from Chuncheon or Suweon was more open in plant type, shorter in plant height, narrower in diameter of pedicel and shorter in inflorescence than those from Iri, Jeonju or Gwangju. Each of the local collections may be regarded as different ecotype, based on the above differences in morphology and responses in growth and flowering to the planting dates. The results appear to imply that Eleocharis kuroguwai weeds occurring in various locations of Korea are different one another in competitive avility with rice crop.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.2
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• pp.21-31
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• 2010

This paper presents a design of PLL and SSCG for reducing the EMI effect at the electronic machinery and tools for DisplayPort application. This system is composed of the essential element of PLL and Charge-Pump2 and Reference Clock Divider to implement the SSCG operation. In this paper, 270MHz/162MHz dual-mode PLL that can provide 10-phase and 1.35GHz/810MHz PLL that can reduce the jitter are designed for 2.7Gbps/162Gbps DisplayPort application. The jitter can be reduced drastically by combining 270MHz/162MHz PLL with 2-stage 5 to 1 serializer and 1.35GHz PLL with 2 to 1 serializer. This paper propose the frequency divider topology which can share the divider between modes and guarantee the 50% duty ratio. And, the output current mismatch can be reduced by using the proposed charge-pump topology. It is implemented using 0.13 um CMOS process and die areas of 270MHz/162MHz PLL and 1.35GHz/810MHz PLL are $650um\;{\times}\;500um$ and $600um\;{\times}\;500um$, respectively. The VCO tuning range of 270 MHz/162 MHz PLL is 330 MHz and the phase noise is -114 dBc/Hz at 1 MHz offset. The measured SSCG down spread amplitude is 0.5% and modulation frequency is 31kHz. The total power consumption is 48mW.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.7 s.337
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• pp.35-40
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• 2005

This paper proposes a fractional-N phase-locked loop (PLL) frequency synthesizer using the 3rd order ${\Delta}{\sum}$ modulator for 900MHz medium speed wireless link. The LC voltage-controlled oscillator (VCO) is used for the good phase noise property. To reduce the lock-in time, a charge pump has been developed to control the pumping current according to the frequency steps and the reference frequency is increased up to 3MHz. A 36/37 fractional-N divider is used to increase the reference frequency of the phase frequency detector (PFD) and to reduce the minimum frequency step simultaneously. A 3rd order ${\Delta}{\sum}$ modulator has been developed to reduce the fractional spur VCO, Divider by 8 Prescaler, PFD and Charge pump have been developed with 0.25um CMOS, and the fractional-N divider and the third order ${\Delta}{\sum}$ modulator have been designed with the VHDL code, and they are implemented through the FPGA board of the Xilinx Spartan2E. The measured results show that the output power of the PLL is about -lldBm and the phase noise is -77.75dBc/Hz at 100kHz offset frequency. The minimum frequency step and the maximum lock-in time are 10kHz and around 800us for the maximum frequency change of 10MHz, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.12
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• pp.1753-1760
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• 2010

This study was designed to investigate the protective effects of Sasa borealis leaves on high glucose-induced oxidative stress in human umbilical vein endothelial cells (HUVECs). Freeze-dried Sasa borealis leaves were extracted with 70% methanol and followed by a sequential fractionation with dicholoromethan, ethyl acetate, butanol and water. The ethyl acetate fraction from Sasa borealis leaves extract (ESLE) was used in this study because it possessed the strongest antioxidant activity among the various solvent fractions. Exposure of HUVECs to 30 mM high glucose for 48 hr resulted in a significant (p<0.05) decrease in cell viability, glutathion (GSH) concentration, activities of antioxidant enzymes including superoxide dimutase (SOD), glutathion peroxidase (GSH-px) and catalase, and a significant (p<0.05) increase in intracellular ROS and lipid peroxidation formation in comparison to the cells treated with 5.5 mM glucose. ESLE treatment decreased intracellular ROS and lipid peroxidation formation and increased cell viability, GSH concentration and expressions of SOD and catalase in HUVECs. These results suggest that ESLE may be able to protect HUVECs from high glucose-induced oxidative stress, partially through the antioxidative defense systems.

• The Journal of the Korea Contents Association
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• v.9 no.11
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• pp.247-253
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• 2009

We investigated the cell growth rate according to the change of temperature of the Thermo-rod used for the local hyperthermia therapy. For this study, we fabricated the Thermo-rods (TR) using Duplex Stainless Steels having magnetic properties as well as non magnetic properties. To evaluate cell growth rates up to 15 days, we conducted cell proliferation test using cell counting methods. For the tests, the CAPEs and Osteoblats were seeded on the 6-we11 plates with the induction heated thermo-rods 30 mins a day for 15 days with 2 days interval and without induction heated thermo-rods as control group respectively. We calculated cell growth rates, 6 hours after heating. From the results, in case of CAPEs and Osteobalsts seeded groups, the cell growth rates in all groups increased drastically for 6 days after seeding, but decreased irregularly after 6 days. In conclusion, the cell growth rates showed no significant difference among all groups and it indicated that there were no effects of temperate ($41^{\circ}C$) on cell growth rates.