• Korean Journal of Soil Science and Fertilizer
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• v.27 no.2
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• pp.98-104
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• 1994

Effects of paddy-upland rotation system on nutrients distribution in soil profile and nutrient balance were studied in paddy fields from 1989 to 1993. The obtained results are summarized as follows. 1. $NO_3{^-}-N$, Av.$P_2O_5$, Ex.-K, and EC were high by small extent in surface layer of 0~20cm soil depth without the sign of salt movement to deeper layers. On the contrary Ex.-ca, Ex.-Mg, and pH became high with increase of soil depths. 2. $NO_3{^-}-N$, Av.$P_2O_5$, Ex.-K, and EC in surface soil were high in the order of Converted, Paddy-Upland Rotation, Potato-Chinese Cabbage>2 Year, Rotation, Potato-Chinese Cabbage>Converted, Paddy-Upland Rotation, Soybean>Continous Paddy, which responded well to fertilizer application rates. On the other hand Ex.-Ca, Ex.-Mg, and pH in whole layers were high in the order of Converted, Paddy-Upland Rotation, Soybean>Converted, Paddy-Upland Rptation, Potato-Chinese Cabbage>2 Year, Rotation, Potato-Chinese Cabbage>Continuous Paddy, which largely depended on plant absorption. 3. Nutrient balance in upland cropping system cultivating potato and Chinese cabbage showed that the input of chemical fertilizer of nitrogen and potassium was less than the plant uptake, while it was reverse for phosphorus with much gap between fertilizer input and plant uptake. Therefore, phosporous was expected to be accumulated by 27kg/10a every year. 4. Nutrient balance in upland cropping system cultivating soybean showed that nitrogen was not deficient to soybean crops even the chemical fertilizer input was less than plant uptake because of nitrogen fixation by rhizobia. However, there was about 1kg/10a deficit of potassium, which resulted dificiency symptom in the middle stage of soybean growth. For phosphorous there was excess of 4kg/10a, which was expected to be short for maintaining phosphorous fertility of upland soils.

• ETRI Journal
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• v.10 no.4
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• pp.75-88
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• 1988

본고는 CCITT에서 통신망의 운용관리를 위해 연구중인 TMN(Telecommunications Management Network)의 개념을 토대로 장차의 통신망에서 필수적으로 요구되는 ISDN 기능과 CCITT의 No.7 기능의 실현을 목표로 하고 국내외적으로 활발한 활용이 예상되는 대용량 전전자 교환기인 TDX-10이 현장에 적용될 경우의 효율적인 운용관리를 위해 요구되는 사항들을 망차원에서 유관센터들의 기능과 관련하여 분석하고, 시스팀화하여 TDX-10 운용 및 보전에 필요한 교환기 유지보수, 과금 및 트래픽 데이터처리, 교환기 DB관리의 다기능을 동시에 제공할 수 있는 운용관리 방식의 구조, 기능 및 TMN환경에서의 외부 환경과의 접속방법 등을 기술한다.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.123-131
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• 1994

Experimental studies were conducted to make clear the soil moisture environment under the condition of paddy-upland rotational fields by investigating water-table depths and soil moisture contents during growing season of crops in two kinds of soil. The following results were obtained. 1.Although water-table depths fluctuated with the amount of rainfall in the experimental field, it seemed that the variation of vater4able depths in the paddy-upland rotational, field was strongly affected by the condition of locations on paddy fields. 2.It is recognized that the concept of sum of excess water depth(SEWxx) and sum of excess water day(SEDxx) can be used to represent the soil moisture stress index due to the fluctuation of water-table depths. 3.The results of this study clearly indicate that drainage in paddy-upland rotational field to maintain an optimum soil moisture content must be made by introducing the concept of block drainage which needs both subsurface drainage and intercept drainage around a field. 4.Soil moisture contents were affected by both the amount of rainfall and water-table depths, however, the moisture content for top soil showed higher correlation with the amount of rainfall while that for subsoil with water-table depths.

• ETRI Journal
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• v.9 no.3
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• pp.33-42
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• 1987

본고는 UNIX O/S(System V)에서 C-언어로 구현된 전전자교환기(TDX-1A) 집중보전시스팀(CSMS-TDX)의 데이터베이스 접근방법을 중심으로 메시지 수집 시스팀에 필요한 기본적인 데이터베이스 모형과 이러한 모형을 활용하기 위해 구현된 access method interface의 각종 알고리즘을 설명한다.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.31-32
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• 2016

본 논문에서는 3레벨 무정전전원장치의 직류링크 전압 불균형을 제거할 수 있는 3레벨 인터리브드 충방전기의 장치 및 제어 기법을 제안하였다. 기존 2레벨에 비해서 3레벨 인터리브드 충방전기는 배터리 전류의 리플감소와 전력변환손실을 절감할 수 있으며, 중성점 전압 제어로 직류링크의 전압편차를 균등화 할 수 있다. 제안된 기법은 방전 시 독립방전모드와 중복방전모드가 자동 전환되며, 간단하고도 효과적으로 중성점 전압제어가 가능하다. 제안된 방식의 유효성은 PSIM 시뮬레이션과 300kVA 무정전전원장치 시제품의 동작파형으로 검증하였다.

• Journal of The Korean Society of Grassland and Forage Science
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• v.16 no.1
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• pp.81-86
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• 1996

Silage wm(cv, Gwanganok) was cultivated during 1991-1994 on paddy land as a rotational cropping system of rice, to evaluate the effect of cattle manure application on the soil characteristics, yield performance and quality of com plant. The treatments used in this study were non-fertilizer, NPK standard in chemical fertilizer(N:$P_2O_5$ : $K_2O$= 200 : 150 : 150 kg/ha), cattle manure 20.40, 60 and 80 ton/ha Application of cattle manure improved soil pH, organic matter, available phosphate and exchangeable cations in the soils. During the experiment, soil pH was improved from 4.7 in the chemical fertilizer application(control) to 5.4-5.6 in the application of cattle manure, and available $P_2O_5$ wntent was increased from 72.2 ppm(contro1) to 340.2 ppm(cattle manure 80 ton/ha). Application of cattle manure increased plant growth, plant height and stalk diameter, and silage yields. Dry matter yields were produced 15.88 ton(chemical fertilizer), 20.11 ton(cattle manure 40 ton) and 21.22 ton/ha(cattle manure 80 ton/ha). However, no signicant yield differences were observed between cattle manure 40, 60 and 80 tonlha Productions of total digestible nutrients(TDN) and net energy for lactation(NEL) were also increased under cattle manure application. From the abobe results, the proper application amount of cattle manure was 40 tonha in this experiment.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.9
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• pp.21-28
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• 2001

The economical detection of dual-tone multi-frequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each chanel has independently a DTMF receiver, and it informs the detected signal to processors. In order to detect the DTMF signals, the receiver use algorithm such DFT, FFT and Goertzel methods. This paper analyze the power spectra of the DTMF receiver by using the QFT algorithm. As experimental results, it show that can the improved performance of the DTMF receiver and can reduce memory waste and the real time processing.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.11C
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• pp.133-139
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• 2001

The economical detection of dual-tone multi-frequency(DTMF) signals is an important factor when developing cost-effective telecommunication equipment. Each channel has independently a DTMF receiver, and it informs the detected signal to processors. In order to detect the DTMF signals, this paper analyze the power spectra of the DTMF receiver by using the QFT algorithm. As experimental result, by analyzing 2$\^$M/ real data in terms of ITU-T specification, it show that the QFT algorithm improve the performance of the DTMF receiver and can save memory waste and can the real-time processing.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.535-542
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• 2017

This paper proposes a simple 3-level interleaved charger-discharger for the uninterruptible power supply (UPS) with various combinations of battery cells. The proposed converter not only improves charging and discharging efficiency, but also reduces the physical volume and the cost. Furthermore, the converter also offers the capability of the neutral point voltage, so that more stable operation can be obtained. In addition, the proposed converter significantly reduces the ripple current of the battery inductor, thereby providing an expected life extension of the battery. Experimental results for a 300kVA UPS prototype verify the validity of the proposed converter. The proposed charger-discharger is suitable for UPSs and energy storage systems (ESSs) with wide input battery voltage ranges.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.206-208
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• 1995

Recently according to the increasing critical loads such as communication and life support systems stable power supplying becomes more and more important. Therefore it is indespensable to stabilize power source using these instruments - AVR(Automatic Voltage Regulator) or UPS(Uninterrutible Power Supply). This paper deals with ON-LNE UPS which is composed of PWM converter for AC-DC conversion. Using a PWM converter have advantages of low current harmonics and high power factor. In this paper ON-LNE UPS using PWM converter is proposed and its characteristics are investigated.