• 한국통신학회논문지
• /
• 제30권2A호
• /
• pp.129-136
• /
• 2005

지정된 비트 크기를 갖는 승산기 코어의 Verilog-HDL 모델을 생성하는 가변 정밀도 승산기 생성기 (VPM_Gen; Variable-Precision Multiplier Generator)에 대해 기술한다. 사용자의 필요에 따라 승수와 피승수의 비트 수를 8-비트${\sim}32$-비트 범위에서 1-비트 단위로 선택할 수 있으며, 승산결과는 $8-b{\sim}64-b$ 범위에서 2-비트 단위로 절사할 수 있도록 함으로써 총 3,455 가지 승산기 코어를 생성할 수 있다. 승산결과가 절사되는 경우, 절사되는 부분의 회로를 제거함으로써 게이트 수와 전력소모가 각각 최대 40%와 30% 감소되도록 하였으며, 이를 통해 효율적인 저전력 승산기 코어가 구현되도록 하였다. 또한, 절사 비트 수에 따른 적응 오차보상 방법을 적용함으로써 절사오차가 최소화되도록 하였다. VPM_Gen에 의해 생성되는 승산기 코어는 Xilinx FPGA 보드와 논리분석기를 통하여 그 기능을 검증하였다.

• 한국지반공학회논문집
• /
• 제33권11호
• /
• pp.5-19
• /
• 2017

본 연구는 전통적인 다짐관리방법의 문제점을 보완하고자 TDR(Time Domain Reflectometry)을 이용하여 지반의 함수비와 건조단위중량을 측정하는 연구를 수행하였다. 개발된 Flat TDR 시스템의 측정값을 검증하기 위해 여섯 가지 시료를 대상으로 실내실험을 수행하였다. 또한 실내실험을 바탕으로 현장시험을 수행하여 현장 적용성을 검토하였고, 신뢰성을 확보하기 위해 Purdue TDR 시스템과 비교실험을 수행하여 정밀도를 확인하였다. 또한 유한요소해석을 수행하여 Flat 프로브의 영향범위를 확인하였다. 그 결과 약 10cm의 영향범위를 확인하였고, 실내실험결과 함수비는 평균적으로 약 0.4%의 오차를 보이며, 건조단위중량의 경우 약 1.6%의 오차를 보였다. 현장시험의 경우 함수비는 0.8%, 건조단위중량의 경우 2.5%의 오차를 보였다. 실험 결과를 통하여 Flat TDR 시스템의 측정값은 기존의 TDR 시스템보다 정확한 값을 도출하는 것을 확인할 수 있었다.

• 한국음향학회지
• /
• 제38권4호
• /
• pp.371-377
• /
• 2019

본 논문에서는 2018년 10월 동해에서 수행된 장거리 수중음향통신의 해상실험 결과를 제시한다. 하나의 송신기와 16개의 수직 배열 수신기를 이용하여 수중음향통신 신호를 수집하였으며, 송신기와 수신기 사이의 거리는 최대 90 km로 하였다. 대표적인 디지털 주파수 변조 기법에 해당하는 BFSK(Binary Frequency Shift Keying) 방식과 BCSK(Binary Chirp Shift Keying) 방식으로 정보를 전송하였다. 실험 결과 60 km 전송 거리에서는 모든 경우에서 오류가 나타나지 않았으며, 90 km 전송 거리에서는 채널 부호화 기법이 적용되지 않은 비부호화 비트 오류율에 있어서 BFSK와 BCSK 두 방식 각각 평균 0.0197과 0.0007을 나타내었다.

• Composite Materials and Engineering
• /
• 제3권3호
• /
• pp.201-220
• /
• 2021

In this study, potential of three machine learning techniques i.e., M5P, Support vector machines and Gaussian processes were evaluated to find the best algorithm for the prediction of flexural strength of concrete mix with steel fibre. The study comprises the comparison of results obtained from above-said techniques for given dataset. The dataset consists of 124 observations from past research studies and this dataset is randomly divided into two subsets namely training and testing datasets with (70-30)% proportion by weight. Cement, fine aggregates, coarse aggregates, water, super plasticizer/ high-range water reducer, steel fibre, fibre length and curing days were taken as input parameters whereas flexural strength of the concrete mix was taken as the output parameter. Performance of the techniques was checked by statistic evaluation parameters. Results show that the Gaussian process technique works better than other techniques with its minimum error bandwidth. Statistical analysis shows that the Gaussian process predicts better results with higher coefficient of correlation value (0.9138) and minimum mean absolute error (1.2954) and Root mean square error value (1.9672). Sensitivity analysis proves that steel fibre is the significant parameter among other parameters to predict the flexural strength of concrete mix. According to the shape of the fibre, the mixed type performs better for this data than the hooked shape of the steel fibre, which has a higher CC of 0.9649, which shows that the shape of fibers do effect the flexural strength of the concrete. However, the intricacy of the mixed fibres needs further investigations. For future mixes, the most favorable range for the increase in flexural strength of concrete mix found to be (1-3)%.

• 한국식품영양학회지
• /
• 제35권6호
• /
• pp.537-542
• /
• 2022

This study was conducted to provide basic data on the amount of sodium and the setting of permissible error range of actual measurement, which is a problem for cabbage kimchi nutrients subject to labeling. The sample targeted was baechu (Kimchi cabbage) kimchi, which might have a large variation in sodium content by part of kimchi. Kimchi samples were collected twice from eight companies by season (spring, summer, fall, and winter). The average sodium content in kimchi samples was 619±87 mg/100 g (range, 534±63 mg/100 g to 783±40 mg/100 g). The error in average annual sodium content of abandonment kimchi (maximum value difference compared to the minimum value) was 26.8 to 64.3%. Sodium contents in kimchi produced in spring and summer were relatively low. However, deviation between individuals was large. It was found that cases exceeding the permissible error (120%) standard varied depending on the criteria for setting the amount of sodium. In addition, due to seasonal differences, sodium content in kimchi exceeded 120% of the labeling value. Thus, it is necessary to set standards suitable for characteristics of kimchi to prevent unintentional violations of labeling standards by raw materials and manufacturing processes.

• 센서학회지
• /
• 제31권3호
• /
• pp.163-167
• /
• 2022

In this study, we investigated a carbon nanotube (CNT) film sensor to detect hazardous and noxious substances distributed in seawater. The response change of the sensor was studied according to environmental temperature, and its temperature coefficient of resistance (TCR, α) was measured. The temperature of the CNT film (~50 ㎛) was in the range of 20-50 ℃, and αCNT was calculated to be -0.0011 %/ ℃. We experimentally confirmed that the CNT film had a smaller TCR value than that of the conventional sensor. Therefore, we investigated the response change of the CNT sensor according to temperature. The CNT sensor showed a relatively small error of approximately 2.3 % up to 30 ℃, which is within the temperature range of the seawater of the Korean Peninsula. However, when the temperature exceeded 40 ℃, the error in the CNT sensor increased by more than 5.2 %. We fabricated a metal oxide (ITO, indium-tin-oxide) film and compared its performance with that of the CNT sensor. The ITO sensor showed an error of >12.5 % at 30 ℃, indicating that in terms of the stability of the sensor to temperature, the CNT film sensor has superior performance.

• Nuclear Engineering and Technology
• /
• 제56권2호
• /
• pp.451-462
• /
• 2024

In order to optimize the operational safety and reliability of the upper launcher for the CFETR ECRH system, a design of the launcher based on the remote steering concept is currently being carried out for comparison with the front steering equivalent. This paper presents the remote steering system's conceptual design and simulation analysis. A Square Corrugated Waveguide (SCW) of 65 × 65 mm has been designed with an optimized length of 9.35 m. By changing the relative length of the waveguide, the transmission efficiency of the SCW is optimized within the range of steering angles ±12°. Different error factors are investigated in detail, and corresponding acceptable error ranges are provided. Considering these error factors and ignoring ohmic losses and thermal effects, the relative transmission efficiency of the SCW is estimated to be >98 % within the steering angle range. A matching steering unit for the SCW is designed, which consists of an ellipsoidal focusing mirror and a steerable flat mirror. The detailed design of the steerable mirror motion trajectory is presented. Also, the influence of the possible beam incident errors caused by the steering unit on the transmission efficiency is analyzed in detail.

• 한국정보과학회논문지:정보통신
• /
• 제35권4호
• /
• pp.282-291
• /
• 2008

본 논문에서는 무선 노드의 이동성에 따른 링크 에러로 인한 Mobile Ad hoc Network (MANET) IP 자동 네트워크 프로토콜(Address Autoconfiguration Protocol: AAP)의 메시지 복잡도를 분석하고자 한다. 링크 에러로 인해 목적지까지 전달되지 못한 메시지는 재전송되어야 하고, 이러한 재전송 횟수 (S)를 링크 에러 확률 ($P_e$)에 따라 계산하는 알고리즘을 제안하였다. 또한, O-표기법에 따라 N개의 노드에 의해 발생된 메시지의 Upper Bound를 각 AAP에서 유도하였다. 본 연구에서 검토된 AAP는 Strong Duplicate Address Detection (DAD), Weak DAD with proactive routing protocol (WDP), Weak DAD with on-demand routing protocol (WDO), MANETconf이다. 컴퓨터 기반 시뮬레이션에서, 제안된 알고리즘에 의해 링크 에러가 있을 때, 각 AAP의 성능을 분석해본 결과, WDP가 가장 낮은 메시지 복잡도를 가졌고, MANETconf가 가장 높은 메시지 복잡도를 보였다.

• 천문학회보
• /
• 제39권2호
• /
• pp.103-103
• /
• 2014

Manufacturing of lens and mirror using Diamond Turning Machine (DTM) offers distinct advantages including short fabrication time and low cost as compared to grinding or polishing process. However, the DTM process can leave mid-frequency error in the optical surface which generates an undesirable diffraction effect and stray light. The mid-frequency error is expected to be eliminated by mechanical polishing after the DTM process, but polishing of soft surface of ductile aluminum is extremely difficult because the polishing process inevitably degrades the surface form accuracy. In order to increase its surface hardness, we performed electroless nickel plating on the surface of diamond-turned aluminum (Al-6061T6) off-axis mirrors, which was followed by the 6-hour-long baking process at $200^{\circ}C$ for improving its hardness. Then we polished the nickel plated off-axis mirrors to remove the mid-frequency error and measured polished mirror surfaces using the optical surface profilometer (NT 2000, Wyko Inc.). Finally, we ascertained that the mid-frequency error on the mirror surface was successfully removed. During the whole processes of nickel plating and polishing, we monitored the form accuracy using the ultra-high accurate 3-D profilometer (UA3P, Panasonic Corp.) to maintain it within the allowable tolerance range (< tens of nm). The polished off-axis mirror was optically tested using a visible laser source and a pinhole, and the airy pattern obtained from the polished mirror was compared with the unpolished case to check the influence of mid-frequency error on optical images.

• 한국통신학회논문지
• /
• 제35권5A호
• /
• pp.504-512
• /
• 2010

본 논문에서는 무선 USB 칩-셋 내 무선통신시스템단에 적용될 수 있는 6비트 800MS/s 플래쉬 A/D 변환기를 설계하였다. 기존의 A/D 변환기에서 서로 독립적으로 사용되던 오차보정회로단과 동기화단을 하나의 회로로 간소화 시켜서, 하드웨어에 대한 부담을 감소시켰다. 제안한 오차보정회로는 기존의 오차보정회로보다 MOS 트랜지스터의 수를 5개 감소시킬 수 있으며, 오차보정회로 한 개당 면적은 9% 정도 감소하게 된다. 설계된 A/D 변환기는 $0.18{\mu}m$ CMOS 1-poly 6-metal 공정으로 제작되었으며 측정 결과 입력 범위 0.8Vpp, 1.8V의 전원 전압에서 182mW의 전력 소모를 나타내었다. 800MS/s의 변환속도와 128.1MHz의 입력주파수에서 4.0비트의 ENOB을 나타내었다.