• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.49-58
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• 2014

A low-swing differential near-ground signaling (NGS) transceiver for low-power high-speed mobile I/O interface is presented. The proposed transmitter adopts an on-chip regulated programmable-swing voltage-mode driver and a pre-driver with asymmetric rising/falling time. The proposed receiver utilizes a new multiple gain-path differential amplifier with feed-forward capacitors that boost high-frequency gain. Also, the receiver incorporates a new adaptive bias generator to compensate the input common-mode variation due to the variable output swing of the transmitter and to minimize the current mismatch of the receiver's input stage amplifier. The use of the new simple and effective impedance matching techniques applied in the transmitter and receiver results in good signal integrity and high power efficiency. The proposed transceiver designed in a 65-nm CMOS technology achieves a data rate of 13 Gbps/channel and 0.3 pJ/bit (= 0.3 mW/Gbps) high power efficiency over a 10 cm FR4 printed circuit board.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.6
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• pp.720-729
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• 2005

In this paper, we design the indirect adaptive controller using Wavelet Neural Network(WNN) for unknown nonlinear systems. The proposed indirect adaptive controller using WNN consists of identification model and controller. Here, the WNN is used in both Identification model and controller The WNN has advantage of indicating the location in both time and frequency simultaneously, and has faster convergence than MLPN and RBFN. There are several training methods for WNN, such as GD, GA, DNA, etc. In this paper, we present the Extended Kalman Filter(EKF) based training method. Although it is computationally complex, this algorithm updates parameters consistent with previous data and usually converges in a few iterations. Finally, ore illustrate the effectiveness of our method through computer simulations for the Buffing system and the one-link rigid robot manipulator. From the simulation results, we show that the indirect adaptive controller using the EKF method has better performance than the GD method.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.14-19
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• 1990

This paper describes on the characteristics of the acoustic echoes from the scattering layers by the aggregation of marine organisms which was measured by using a 50kHz echo sounder on board of the training ship SAEBADA belong to National Fisheries University of Pusan during the summer, 1989 in the East China Sea. A data acquisition system was used to record digitally the envelope of the echoes and the frequency distribution of echo amplitudes on the whole water column was examined as a function of time during the sunrise and sunset periods. Acoustic data showed that the abundance distribution of marine organisms according to depth in the servery area changed with time and that the organisms were most active during the twilight of morning, and the echo strength on the water column or scattering layer was also strongest during this time. Additional results of this survey suggest that other interest, such as the relationship between environmental conditions and biomass depth distribution, could be also investigated in hydroacoustic method.

• The Korean Journal of Pain
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• v.1 no.2
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• pp.164-170
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• 1988

Neurolysis of the celiac plexus is performed to relieve intractable pain caused by carcinoma of the stomach, liver and pancreas, and upper abdominal metastasis of tumors having more distant origins. It is also occasionally effective in controlling the pain of chronic pancreatitis. Alcohol celiac plexus blocks were done in 22 patients of whom 18 had intractable upper abdominal pain from cancer and 4 had pain from chronic pancreatitis. In most cases, an initial diagnostic block with 0.2 percent bupivacaine was followed by the therapeuntic block performed by injecting 50ml of 60 percent ethyl alcohol. Good to excellent pain relief occurred in 86 percent of patients. Duration of pain relief was from 4 months to 7 months in 55 percent of patients. Complications and side effects were infrequently seen but did include a 16 percent decrease of mean systolic arterial pressure and 16 cases of facial flushing. This block is remarkably safe as well as effective for the relief of upper abdominal pain from cancer origin.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.30 no.4
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• pp.307-313
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• 2019

The traveling wave tube amplifier (TWTA), which can be applied to the Ka-band millimeter-wave multi-mode seeker, consists of an high voltage power supply(HVPS), a grid modulator, a command and control, and an RF assembly. We designed a power supply that generates a -17.9 kV high voltage by synchronizing the pulse repetition frequency(PRF) and power supply switching frequency(i.e. synchronization frequency), and a high-speed grid-switching modulator for RF pulse modulation. The TWTA, which is fabricated through miniaturization with a volume of 3.18 L, has high pulse switching characteristics of up to 18.5 ns. The maximum rise/fall time of the grid on/bias signal and peak power is more than 564.9 W. Moreover, an excellent spurious performance of -68.4 dBc or less was confirmed within the range of PRF and PRF/2.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.1
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• pp.37-42
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• 2021

This paper presents a jitter and phase noise characteristic improved phase-locked loop (PLL) with loop filter voltage detector(LFVD) and frequency voltage converter(FVC). Loop filter output voltage variation is determined through a circuit made of resistor and capacitor. The output signal of a small RC time constant circuit is almost the same as to loop filter output voltage. The output signal of a large RC time constant circuit is the average value of loop filter output voltage and becomes a reference voltage to the added LFVD. The LFVD output controls the current magnitude of sub-charge pump. When the loop filter output voltage increases, LFVD decreases the loop filter output voltage. When the loop filter output voltage decreases, LFVD increases the loop filter output voltage. In addition, FVC also improves the phase noise characteristic by reducing the loop filter output voltage variation. The proposed PLL with LFVD and FVC is designed in a 0.18um CMOS process with 1.8V power voltage. Simulation results show 0.854ps jitter and 30㎲ locking time.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.407-407
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• 2021

토양수분량은 그 양은 작지만 다양한 수문현상에 관여하는 주요한 수문인자 중 하나이다. 특히, 강우, 유출, 홍수 및 가뭄 등과 직접적인 연관이 있어 국내에서도 그 중요성이 점차 강조되고 있다. 일찍이 해외에서는 토양수분량 위성자료나 관측기기의 검증 및 교정을 위해 다수의 지상 관측소를 운영해왔으며, ISMN(International Soil Moisture Network)과 같은 기관을 통해 자료의 취합 및 품질관리, 배포 등도 활발하게 이루어지고 있다. 최근 국내에서도 최신 관측기기의 도입이나 수자원위성의 개발 등 토양수분량에 관한 연구가 점차 활발하게 이루어지고 있으며, 위성자료와 관측기기의 검증 및 교정을 위한 지상관측소도 점차 확대되고 있는 추세이다. 하지만, 국내 지상관측소는 현재 다양한 기관과 단체에 의해 운영되고 있으며, 품질관리 기준이 통일되어 있지 않아 자료의 접근 및 활용 측면에서 개선이 필요한 실정이다. 이에 한국수자원조사기술원은 국내 환경에 맞는 품질관리 기준을 제시하고, 자료의 접근성 및 활용성 개선의 토대를 마련하고자 품질관리 시스템을 개발하고 있다. 본 연구는 정량화된 품질관리 기준을 바탕으로 spike를 판별하는 알고리즘에 대한 성능평가를 다루고 있으며, 청미천 토양수분량 관측소 2020년 자료에 임의의 튀는 값(spike)을 추가하고, 해당 이상치의 검출여부를 확인하는 방식으로 진행되었다. 각각의 지점자료에서 강우사상 중 하강부, 무강우기간 중 하강부를 1개씩 선정하고, 해당 구간에 positive spike를 추가한 case와 negative spike를 추가한 case를 생성해 강우조건 및 spike 유형에 따른 검출성능 차이를 평가했다. 평가 결과, 강우기간 검출률 84.3%, 무강우기간 검출률 96.3%로 강우조건에 따른 성능차이가 명확하게 나타났으며, positive spike는 91.7%, negative spike는 88.9%로 spike 유형에 따른 검출성능차이는 미미했다. 강우조건과 spike 유형을 동시에 고려했을 때는 무강우기간의 positive spike가 98.2%로 가장 높은 검출률을 보인 반면에 강우기간의 negative spike는 83.3%로 가장 낮은 검출률을 보였다. 알고리즘이 검사시간대를 중심으로 24시간 동안의 토양수분량 변화를 감지하기 때문에 강우기간에 검출성능이 저하되는 것으로 판단되며, 이를 개선하기 위해선 강우사상에 따른 유동적인 window size 조절 알고리즘의 추가가 필요할 것으로 판단된다.

• Journal of Bio-Environment Control
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• v.17 no.2
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• pp.90-95
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• 2008

It has become a big matter of concerns that the skill and measures against reduction of energy and cost for heating a protected horticultural greenhouse were prepared. But in these days necessity of cooling a protected horticultural greenhouse is on the rise from partial high value added farm products. In this study, therefore, a horizontal type geothermal heat pump system with 10 RT scale to heat and cool a protected horticultural greenhouse and be considered to be cheaper than a vertical type geothermal heat pump system was installed in greenhouse with area of $240\;m^2$. And cooling performances of this system were analysed. As condenser outlet temperature of heat transfer medium fluid rose from $40^{\circ}C$ to $58^{\circ}C$, power consumption of the heat pump was an upturn from 11.5 kW to 15 kW and high pressure rose from 1,617 kPa to 2,450 kPa. Cooling COP had the trend that the higher the ground temperature at 1.75 m went, the lower the COP went. The COP was 2.7 at ground temperature at 1.75 m depth of $25.5^{\circ}C$ and 2.0 at the temperature of $33.5^{\circ}C$ and the heat extraction rate from the greenhouse were 28.8 kW, 26.5 kW respectively at the same ground temperature range. 8 hours after the heat pump was operated, the temperature of ground at 60 cm and 150 cm depth buried a geothermal heat exchanger rose $14.3^{\circ}C$, $15.3^{\circ}C$ respectively, but the temperature of ground at the same depth not buried rose $2.4^{\circ}C$, $4.3^{\circ}C$ respectively. The temperature of heat transfer medium fluid fell $7.5^{\circ}C$ after the fluid passed through geothermal heat exchanger and the fluid rejected average 46 kW to the 1.5 m depth ground. It analyzed the geothermal heat exchanger rejected average 36.8 W/m of the geothermal heat exchanger. Fan coil units in the greenhouse extracted average 28.2 kW from the greenhouse air and the temperature of heat transfer medium fluid rose $4.2^{\circ}C$after the fluid passing through fan coil units. It was analyzed the accumulation energy of thermal storage thank was 321 MJ in 3 hours and the rejection energy of the tank was 313 MJ in 4 hours.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.797-807
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• 2008

For this study, the semi-adiabatic temperature rising test is accomplished by using ternary system cement (OPC, BFS, FA) reducing temperature crack. Two tests are conducted; one is for the paste test, and the other is for the concrete test. As the results of paste tests, using fly ash is better to reduce hydration temperature than doing blast furnace slag. In the case of the paste mixed ternary system cement, the more fly ash is mixed and the less blast furnace slag is used, the lower the temperature is. The less the mixture ratio of blast furnace slag is and the more the mixture ratio of fly ash is, the later the temperature rising velocity and descending velocity are. Besides, the temperature is lower if water/binder ratio is high. The use of ternary system cement has the retardation effect of temperature rising because the time to reach the maximum temperature is in the order of OPC100, binary system cement, and ternary system cement. From the test, the maximum temperature of concrete used ternary system cement is $8{\sim}11^{\circ}C$ lower than that of concrete used OPC100. Moreover, temperatures rising velocity and descending velocity of ternary system cement range $47{\sim}51%$ and $37{\sim}42%$ compared with OPC100. The specimen of concrete shows remarkable low internal temperature and slow temperature rising velocity and descending velocity compared with the specimen of paste because it is that temperature loss of concrete is much more than paste specimen according to aggregates.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.3
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• pp.213-221
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• 2007

In response to anthropogenic global warming due to a buildup greenhouse gas, the effect of the air temperature on water temperature has been noticed and some efforts have been made to build an air/water temperature relationship at the Masan Bay area by the Ministry of Maritime Affairs & Fisheries (MOMAF). As a result of analyzing the auto- and cross-correlation coefficient between air/water temperature, high correlation $(\sim0.9)$ is shown and the correlation coefficient of air temperature is higher than that of water temperature at the lag time less than approximately 10 days. Separate functions are fitted to the air/water relationship at the Masan Bay to take hysteresis into account. The slopes of the straight line for the rising limb are 0.829 and 0.774 for MA1 and MA2 station respectively, while 1.385 and 1.444 ($\sim1.75$ times larger) for the falling limb. Consequently, the seasonal hysteresis should be considered in order to determine an air/water relationship and accurately estimate the water temperature using the air temperature at Masan Bay.