• 대한의용생체공학회:의공학회지
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• 제19권2호
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• pp.143-152
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• 1998

In this paper, we present the performances of a Doppler system using single channel RF(Radio Frequency) sampling. This technique consists of undersampling the ultrasonic blood backscattered RF signal on a single channel. Conventional undersampling method in Doppler imaging system have to use a minimum of two identical parallel demodulation channels to reconstruct the multigate analytic Doppler signal. However, this system suffers from hardware complexity and problem of unbalance(gain and phase) between the channels. In order to reduce these problems, we have realized a multigate pulsed Doppler system using undersampling on a single channel, It requires sampling frequency at $4f_o$(where $f_o$ is the center frequency of the transducer) and 12bits A/D converter. The proposed " single-Channel RF Sampling" method aims to decrease the required sampling frequency proportionally to $4f_o$/(2k+1). To show the influence of the factor k on the measurements, we have compared the velocity profiles obtained in vitro and in vivo for different intersequence delays time (k=0 to 10). We have used a 4MHz center frequency transducer and a Phantom Doppler system with a laminar stationary flow. The axial and volumetric velocity profiles in the vessel have been computed according to factor k and have been compared. The influence of the angle between the ultrasonic beam and the flow axis direction, and the fluid viscosity on the velocity profiles obtained for different values of k factor is presented. For experiment in vivo on the carotid, we have used a data acquisition system with a sampling frequency of 20MHz and a dynamic range of 12bits. We have compared the axial velocity profiles in systole and diastole phase obtained for single channel RF sampling factor.ng factor.

• 한국정보시스템학회지:정보시스템연구
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• 제16권1호
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• pp.135-158
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• 2007

The purpose of this research is to identify multidimensional motivation factors that determine the piracy of copyrighted digital music. The model is based on TPB(theory of planned behavior) as well as other models in consumer behavior. An empirical study resulted in the following findings. first Both individual's attitude toward music piracy and individual's perceived behavior control have positive impacts on the individual's behavioral intention of piracy. It turned out that perceived behavior control has a stronger impact on behavioral intention than attitude does. Second, the level of individual's moral judgment has negative impacts on both the attitude and behavioral intention toward music piracy. Third, individual's experience in music piracy positively affects the attitude, but does not directly or indirectly affect the behavior intention. Fourth, an economic gain from music piracy is not a significant factor in determining both attitude and behavioral intention. Fifth, the risk of being prosecuted for music piracy is a major factor in determining one's attitude, although the risk is not significant enough to change one's behavioral intention. This research found that individuals' intention to pirate digital music is mainly affected by the moral and ethical standards of the individuals and by the extra resources and abilities they possess. Such factors as economic gain and law enforcement were not significant enough to alter one's behavioral intention. This research is significant in that it established a behavioral model to understand the piracy of copyrighted digital music and that it empirically tested the model with Internet users in Korea. This is one of the first empirical studies in Korea to touch such ethically and perhaps politically sensitive issues as online music piracy.

• Asian-Australasian Journal of Animal Sciences
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• 제17권8호
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• pp.1150-1157
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• 2004

This experiment was conducted to investigate effects of phase feeding and sugar beet pulp (SBP) on growth performance, nutrient digestibility, nitrogen excretion, blood urea nitrogen (BUN) concentration and carcass characteristics in finishing pigs. A total of 128 pigs were allotted at 53.9 kg BW to 8 replicates in a 2$\times$2 factorial arrangement in a randomized complete block (RCB) design. The first factor was phase feeding (2 or 3 phase feeding) and SBP (SBP: 0% or 10%) was the second factor. Ten percent SBP supplement groups showed lower average daily feed intake (ADFI) than 0% SBP supplement groups (p<0.05). However, there were no significant difference in average daily gain (ADG) and feed:gain ratio among treatments during overall experimental period. Nutrient digestibility was not affected by phase feeding or SBP supplementation. Urinary nitrogen excretion in 10% SBP supplement group was lower than that in 0% SBP supplement group (p<0.05) and total nitrogen excretion was lower in SBP supplement group than in the group without SBP. Urinary and total nitrogen were numerically decreased in three phase feeding compared to two phase feeding. The BUN concentration in three phase feeding groups was lower than two phase feeding groups at 47 and 63 day (p<0.05). Consequently, results of this experiment demonstrated that three phase feeding was more acceptable than two phase feeding for finishing pigs. And sugar beet pulp could be supplemented in finishing pig diet for decreasing urinary nitrogen excretion without retardation in growth performance of pigs.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.265-271
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• 1992

It is the purpose of this paper to present a dialogical designing method for control system using a rough grasp of the unknown process property. We deal with a single-input single-output feedback control system with a fuzzy controller. The process property is roughly estimated by the step response, and the fuzzy controller is interactively modified according to the operator's requests. The modifying rules mainly derived from computer simulation are useful for almost every process, such as an unstable process and a non-minimum phase process. The fuzzy controller is tuned by taking notice of four characteristics of the step response: (1) rising time, (2) overshoot, (3) amplitude and (4) period of vibration. The tuning position of the controller is fourfold: (1) antecedent gain factor GE or GCE, (2) consequent gain factor GDU, (3) arrangement of the antecedent fuzzy labels and (4) arrangement of the control rules. The rules give an instance to the respective items of the controller in an effective order. The modified fuzzy PI controller realizes a good response of a stable process. However, because the GDU tuning becomes difficult for the unstable process, it is necessary to evaluate the stability of the process from the initial step response. The fuzzy PI controller is applied to the process whose initial step response converges with GDU tuning. The fuzzy PI controller with modified sampling time is applied to the process whose step response converges under the repeated application of the GDU tuning. The fuzzy PD controller is applied to the process whose step response never converges by the GDU tuning.

• Asian-Australasian Journal of Animal Sciences
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• 제18권4호
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• pp.532-537
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• 2005

Increasing of body weight has been one of the important economic factors in the poultry industry. Insulin-like growth factor (IGF)-I is a polypeptide that serves to regulate muscle development and body growth. Moreover, IGF-I is related to feed efficiency. However, there are few studies regarding the regulatory roles of chicken IGF-I/-II compared with that of mammals. Especially, the Korean Native Ogol Chicken (KNOC) has a lean body growth and its body weight is generally lighter than the broiler chicken. Therefore, this study was conducted to investigate associations among serum IGF-I/-II concentration, feed efficiency, and body growth in KNOC. The body weight and feed intake of KNOC were recorded from 20 to 36 weeks at 2 weeks intervals, and blood was taken every 2 weeks. Serum IGF-I/-II were measured by RIA. Chickens were divided into two groups, high and low serum IGF-I concentration. Generally, feed efficiency and growth performance (body weight and weight gain) in the high serum IGF-I group were higher than those of the low group during the experimental period. In particular, the body weight of the IGF-I high group were significantly different from those of the IGF-I low group at 34 and 36 weeks, respectively (p<0.05). Moreover, body weight, weight gain, and feed efficiency had a significant correlation with serum IGF-I at several weeks (p<0.05 and p<0.01). These results show that IGF-I plays an important role in body growth and suggests a possibility that serum IGF-I could be used as a selection marker for body growth in KNOC.

• 조명전기설비학회논문지
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• 제19권8호
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• pp.116-121
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• 2005

전류모드 아날로그 회로를 이용하여 FIR(Finite Impulse Response) 필터를 설계하는 경우에 tap coefficient와 전류모드 FFT(Fast Fourier Transform) LSI의 회전인자(twiddle factor)를 실현시키기 위해서는 높은 정밀도를 갖는 전류 감쇠 회로가 필요하게 된다. 본 논문은 전류 모드 신호처리 기술에서 전류감쇠 회로의 감쇠 정밀도를 향상시킬 수 있는 기술을 소개하고자한다. 먼저 게이트 길이 비율을 조정하는(gate-ratioed) Current Mirror 회로를 사용하는 기존의 전류 감쇠 조정회로에 있어서의 DC offset 전류 에러에 대하여 분석하였으며, 다음으로 DC offset 전류 에러를 제거할 수 있는 전류감쇠 회로를 제안하였다. 회로 구성은 입력 전류를 1/N로 감쇠시킬 수 있도록 N개의 Current Mirror를 병렬로 연결하는 기본 구성을 하였으며, Kirchhoff 전류 법칙에 근거하여, 전류 감쇠가 결정되도록 설계하였다. 또한 Current Mirror 회로에서, 정전류원의 사용을 줄일 수 있는 회로설계를 제안하였다. 제안된 전류 감쇠 회로에서 정밀도는 Current Mirror의 ac 이득 에러에 의하여 제한되며 High Swing Current Mirror를 기본 Current Mirror로 사용한 경우에, 최대 정밀도는 이론상 입력 전류의 -80[dB]까지 실현가능하다.

• 전기전자학회논문지
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• 제23권3호
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• pp.1112-1115
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• 2019

본 논문에서는 정찰포탄의 활공날개에 적용할 수 있는 새로운 평판형 무지향성 마이크로스트립 안테나를 제안하였다. 제안한 안테나는 무지향성 방사패턴을 얻기 위하여 얇은 기판에 7개의 정육각형 공진기를 준원형을 배열한 구조를 가지고 있다. 안테나 기판의 하단부에 그물망 형태로 이루어진 접지선 구조를 적용하여, 안테나의 공진주파수와 임피던스 대역폭에 관한 연구를 수행하였다. 그물망 형태의 접지선 구조의 유효성을 검증하기 위하여, 접지선의 선폭을 이론적으로 분석하여 상대 대역폭, Q-factor 및 안테나 이득을 만족시키기 위한 최적화 기법을 수행하였다. 제안한 안테나는 모의실험결과와 유사한 측정결과를 보임으로써, 무지향성 방사패턴이 잘 형성됨을 시연하였다. 마지막으로 제작한 안테나 시제품은 5.77 GHz를 중심으로 약 5.65%의 상대대역폭에 해당하는 326 MHz의 동작대역폭을 확인하였으며, 공진주파수 5.84 GHz에서 5.49 dBi의 안테나 이득을 확인하였다.

• 대한본초학회지
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• 제39권1호
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• pp.11-21
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• 2024

Objectives : This study aims to analyze the anti-obesity effect of Syzygium aromaticum L. (SA) in obese mice made by a 60% high-fat diet (HFD). Methods : The antioxidant activities of SA were evaluated in vitro. To assess the anti-obesity effect of SA, male C57BL/6 mice were divided into five groups: Normal, Control, GC100 (Garcinia cambogia 100 mg/kg/day), SA100 (SA 100 mg/kg/day), SA200 (SA 200 mg/kg/day). All groups underwent a 6-week regimen of HFD and oral administration, except for the Normal group. Subsequently, we performed blood analysis, western blotting, and histopathological staining. Results : SA demonstrated effectiveness in antioxidant measurements. SA treatment resulted in a significant decrease in body weight gain, along with reductions in liver and epididymal fat weights. Serum triglyceride (TG), total cholesterol (TC), glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), and leptin levels were reduced with SA treatment. Moreover, in the SA100 group, the reduction of both TG and TC synthesis was caused by inhibiting the sterol regulatory element-binding transcription factor 1 (SREBP-1) and sterol regulatory element-binding transcription factor 2 (SREBP-2) through the Sirtuin 1 (Sirt1)/phospho-AMP-activated protein kinase (p-AMPK) pathway. Furthermore, SA treatment at a dose of 100 mg/kg reduced the accumulation of lipid droplets in the liver and the adipocyte size of the epididymal fat. Conclusion : Our research reveals the anti-obesity effects of SA by demonstrating its ability to inhibit body weight gain and lipid accumulation, suggesting that SA might be promising for obesity treatment.

• 디지털융복합연구
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• 제11권12호
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• pp.237-243
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• 2013

기업은 시작과 동시에 계속기업을 영위하면서 사회적 책임도 가지게 된다. 하지만 최근 기업의 평균수명이 점점 단축되고 있으며 기업환경 또한 급격하게 변화하고 있다. 따라서 본 연구에서는 글로벌 기업의 장수요인 분석을 통하여 기업의 장수, 즉 계속기업의 해답을 얻고자 하였다. 지멘스와 듀폰의 두 거대 글로벌기업의 장수요인을 분석해 본 결과 그 요인은 사업포트폴리오 변화, 위험관리, 지속적 연구개발, 신뢰경영, 친환경경영등의 요인이 설명되었다. 이는 지속적 내, 외부 환경 분석 및 핵심역량 강화를 통한 책임경영의 구현이 곧 장수경영의 핵심으로 나타나고 있다.

• 전자공학회논문지
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• 제51권9호
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• pp.165-170
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• 2014

음성 인식을 위한 전처리기로 주변 잡음을 제거해 주는 음성향상 기법이 강조되고 있다. 다양한 음성향상 기법들 중 코드북 기반 음성향상 기법은 nonstationary 잡음 환경에서도 효율적으로 동작한다. 하지만, 기존 코드북 기반 음성향상 기법에서는 입력 신호와 음성 및 잡음 코드벡터 간에 미스매치가 발생하여 부정확한 게인이 추정되는 문제가 있다. 본 논문에서는 부정확한 게인을 보상하기 위해 long-term 잡음 추정 알고리즘을 사용하여 매 프레임 별로 신호 대 잡음비기반의 Normalized Weighting Factor (NWF)를 구하고, 이것을 기존 게인에 보상하는 방식을 제안한다. 제안된 코드북 기반 음성향상 기법은 기존 코드북 기반 음성향상 기법에 비해 향상된 성능을 보였다.