• 한국전자파학회논문지
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• 제12권7호
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• pp.1086-1093
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• 2001

본 논문에서는 n차 오차신호발생기(error signal generator)를 이용한 postdistortion 방식의 RF 전력증폭기의 선형화 기법을 제안하였다. n차 ESG(error signal generator)는 전력증폭기의 기저대역 등가 복소 전달함수를 바탕으로 오차신호를 발생시켜, 이를 전력증폭기의 출력 단에서 n차 이하의 비선형성만을 제거한다. 따라서, 출력 단의 n차 이상의 혼변조 왜곡(intermodulation distortion) 성분에 영향을 미치지 않으며, 개루프(open-loop) 형태이므로 시스템의 안정성을 보장할 수 있다. 또한, 전력증폭기의 입력 신호를 이용하여 오차신호를 발생시키므로 feedforward 방식에서와 같이 오차신호 발생에 따른 주신호 경로(main signal path)의 시간지연 회로가 불필요하다. 실험 결과로 7차 ESG를 이용한 postdistorter를 최대 출력이 5 W인 셀룰러 대역 A급 증폭기에 적용한 경우의 혼변조 왜곡 개선도와 3-carrier CDMA 신호를 이용한 측정 결과를 제시하여 본 방법의 타당성을 검증하였다.

• 사상체질의학회지
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• 제19권2호
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• pp.30-39
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• 2007

1. Objectives The Face is an important standard for the classification of Sasang Constitution. We are developing 3D Automatic Face Recognition Apparatus(3D-AFRA) to analyse the facial characteristics. This apparatus show us 3D image and data of man's face and measure facial figure data. So we should examine the figure restoration error of 3D Automatic Fare Recognition Apparatus(3D-AFRA) in hardware Error Analysis. 2. Methods We scanned Face status by using 3D Automatic Face Recognition Apparatus(3D-AFRA). And also we scanned Face status by using laser scanner(vivid 9i). We compared facial shape data be restored by 3D Automatic Face Recognition Apparatus(3D-AFRA) with facial shape data that be restorated by 3D laser scanner. And we analysed the average error and the maximum error of two data. 3. Results and Conclusions In frontal face, the average error was 0.48mm. and the maximum error was 4.60mm. In whole face, the average error of was 0.99mm. And the maximum error was 6.64mm. In conclusion, We assessed that accuracy of 3D Automatic Face Recognition Apparatus(3D-AFRA) is considerably good.

• 한국전자파학회지:전자파기술
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• 제5권1호
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• pp.40-50
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• 1994

자신이 위치를 파악하는 전자항해 시스템 중에서도 저궤도 위성인 GPS 위성을 이용한 위치측정 방식은 지구상 어느곳에서 언제든지 고정밀 3차원의 전천후 실시간 위치측정이 가능한 방식이다. 이 GPS위성의 전파가 통과하게 되는 전리층의 변화를 분석하기 위하여 전리층 변동에 다른 현상을 관측하여 GPS 위성에 의한 위치 측정 오차와 전리층 변화와의 관계를 모델링 하여 임의의 지역에서의 GPS 수신기에 의한 실제의 샘플 데이타를 사용하여 시간, 양각, 방위각 등을 변화시켜 가면서 컴퓨터 시뮬레이션을 통하여 성능을 비교 분석하였다 실험결과 제안한 단일 주파수 GPS 사용자일 경우에 전리층 시간지연은 어느정도의 오차가 존재하지만 실제 실험에의한 시간지연이 5~6nsec이고 본 논문에서의 결과가 상태가 양호한 경우에는 5~7nxec정도까지 근접함을 알 수 있었다. 이것은 본논문에서의 전리층 전파특성 알고리듬이 실제 실험 결과치와 근하하게 일치함을 나타낸다.

• Journal of applied mathematics & informatics
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• 제15권1_2호
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• pp.29-51
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• 2004

In this paper, we propose a new mixed finite element method, called the characteristics-mixed method, for approximating the solution to Burgers' equation. This method is based upon a space-time variational form of Burgers' equation. The hyperbolic part of the equation is approximated along the characteristics in time and the diffusion part is approximated by a mixed finite element method of lowest order. The scheme is locally conservative since fluid is transported along the approximate characteristics on the discrete level and the test function can be piecewise constant. Our analysis show the new method approximate the scalar unknown and the vector flux optimally and simultaneously. We also show this scheme has much smaller time-truncation errors than those of standard methods. Numerical example is presented to show that the new scheme is easily implemented, shocks and boundary layers are handled with almost no oscillations. One of the contributions of the paper is to show how the optimal error estimates in $L^2(\Omega)$ are obtained which are much more difficult than in the standard finite element methods. These results seem to be new in the literature of finite element methods.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권1호
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• pp.45-56
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• 2015

본 연구에서는 문맥 정보를 함께 고려해야만 인식할 수 있는 단어 오류에 대하여 오류 인식 방법과 수정 후보 생성 방법을 제안한다. 이 문제는 기존의 영어권에서 이미 많이 다룬 연구 주제이다. 본 연구에서는 영어 자동채점 시스템에서 사용하도록 특화된 방법을 제안한다. 문맥 정보를 고려한 단어 오류 검사에서는 자주 혼동되어 사용되는 단어집합(confusion set)을 활용한다. 비영어권 사용자의 작문 특성을 반영하기 위해 기존의 영어권에서 구축한 혼동집합 이외에 자동으로 혼동집합을 구축하여 실험해 보았다. 또한 품사 중의성으로 인해 기존의 구문오류 검사기가 다루지 못하는 오류를 정의하고 오류 인식과 오류수정 후보를 생성하는 방법을 제안한다. 실제 한국어가 모국어이면서 초/중급 작문 수준의 수험생들이 작성한 영어 문장에 대해 평가해 본 결과, 약 70.48%의 f1 값을 얻어 기존의 영어권 결과에 비해 뒤지지 않는 성능을 보였다.

• 한국정보과학회논문지:시스템및이론
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• 제26권10호
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• pp.1225-1236
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• 1999

기존의 오류 제어 방법들은 실시간 특성과 신축적인 신뢰성을 가지는 멀티미디어 통신 응용의 특징을 충분히 반영하지 못하고 있다. 본 연구는 기존의 재전송을 기반으로 하는 방법에 두 가지 기법을 추가하여 이 문제에 접근하였다. 첫째, 실시간 데이타의 마감 시간을 고려하여 미리 재전송을 실시하는 사전 재전송과 시간적으로 불가능하다고 판단될 때 복구를 포기하는 재전송 포기를 통한 적시 재전송 기법이다. 둘째, 요구되는 신뢰성에 근접하도록 오류가 많이 발생하였을 때만 재전송을 하는 선택적 오류 제어 기법이다. 본 연구는 두 기법을 적용한 오류 제어 프로토콜을 구현하고 네트워크 환경을 바꾸어 가며 성능을 검사하였다. 실험 결과, 제안된 오류 제어 방법은 전체적인 오류 제어 부하는 감소시키면서 오류 복구율을 높인다는 점을 확인하였다.Abstract The current error control schemes do not fit well to the characteristics of multimedia communications: real-time transmission and flexible reliability requirements. This research proposes a new error control scheme, which extends the retransmission-based error control with the following two mechanisms. First, error recovery is performed in two timely fashions: one is retransmission in advance where a retransmission is performed early enough for the deadline if an error is suspected, and the other is retransmission abort where a retransmission is given up if its recovery within the deadline seems to be impossible. Second, error control is selectively performed only when an actual error rate approaches to the threshold on a given reliability requirement. The proposed scheme has been implemented and experimented in various network environments. The performance results show that it has lower control overhead and higher error recovery than the existing schemes.

• Child Health Nursing Research
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• 제5권1호
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• pp.48-58
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• 1999

The purpose of this study was to determine the most accurate technique measuring the apical pulse rate, using three counting duration 15, 30 and 60 seconds, and two methods start ‘0’ and start ‘1’. The instrument used in the study was the EKG monitor, stethoscope and stopwatch. Data was analyzed by utilizing SPSSWIN program. General characteristics of the subjects were analyzed by frequency, percentile, mean, SD. The subject of this research is made up of 46 children and 20 nurses. The children were infants, & under the age of 5. They were hospitalised in PICU & NICU in 2 tertiary hospitals in seoul from Jan. 1. 1998 to Sep. 10. 1998. The measurement of starting 1 & measurement of starting ‘0’ used the T-test to find out the measurement error. Apical pulse duration of 15, 30, 60 seconds were used to find out measurement error, the measurement error depend on experience of Nurse were analyzed by using ANOVA. The result of this study are as follows. 1. When comparing the starting poin of apical pulse 0&1, starting with 1 the measurement error is less, but not statiscally significant. 2. When counting the apical pulse by 15, 30,60 sec. ; 60 seconds counting duration was more accurate, but not statistically significant. 3. The mean of measure error ; Group under 100/min, is 10.33 ; from 100 re 119/min, is 8.30 ; from 120 to 139/min, is 4.76 ; from 140 to 159/min, is 6.09 ; above 160, is 17.83. The differences of these groups are statistically significant. When 60sec were counted, under 140/min the mean of measurement error is 3.4. Also when 30 seconds were counted from 140/min to 159/min the measurement error is 7.14, above 160/min the measurement error is 16.4. That measurement mean is the smallest than the other durations. During the 15 sec. count the measurement error was the largest of them all. 4. By the experience of the nurses, the apical pulse count measurement error was discovered. Under a year experience this measurement error was the largest(11.09), 1 year to under 3 years, the error is the smallest(4.86). 3 year to under 6 years the error is 8.33, 5 years above the error is 6.11 but this is not statistical significant. Under a year experience when counting 15, 30, 60 seconds the error is the largest. The group of the nurses from a year to under 3 years, the measurement error is the smallest of all the groups. The result of the study is to determine the technique measuring the apical pulse rate, Hargest (1974), starting point ‘0’ is not proved. When the pulse rate increases the 30 sec measurement rate is accurate. Under 140/min the 60 sec measurement rate is the most accurate. Depending on the nurses experiences, there is a variable difference to the apical pulse rate measurement. Especially new nurses training courses should enforce the children’s pulse rate count and the basic vital signs.

• 한국산학기술학회논문지
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• 제20권4호
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• pp.489-496
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• 2019

본 논문은 철도차량 및 자동차용 패널의 진동 및 소음억제용으로 사용되는 감쇠 처리재의 감쇠특성 평가에 관한 연구이다. 감쇠재의 모드별 매개변수들을 구하기 위해 다른 종류의 PVC를 알루미늄과 철계 빔위에 도포한 시편을 제작하여 가진시험을 수행하였다. 시편은 10 Hz부터 1,000 Hz까지의 주파수 대역을 조화력으로 가진하여 가속도계로 전달 모빌리티값을 측정하였다. 감쇠계수는 몇 가지 이론인 반력법, 최소 탄젠트오차법 및 최소 각오차법 조합법과 위상변화법을 모드 원호곡선 맞춤과 최소자승오차법을 사용하여 작성한 통합 프로그램을 이용하여 평가하였다. 감쇠값이 비교적 낮고 측정값이 선형인 경우는 어느 방법을 사용해도 되나, 감쇠값이 높거나 측정값에 비선형특성이 있는 경우에는 최소 각오차법이 감쇠계수 측정오차를 줄일 수 있다. 도포 감쇠재의 동적특성 평가로부터 구한 재료의 물성값은 차체나 철도차량 하부 기기함과 같이 복잡한 구조물의 소음해석을 위한 유한요소법에 사용할 수 있다. 빔 시험에서 수행한 모드별 감쇠계수의 특성 평가 결과 2차 이상 모드의 주파수 대역에서 감쇠 효과가 크기 때문에 구조소음억제에 유용할 것으로 사료된다.

• 한국안전학회지
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• 제24권3호
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• pp.71-78
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• 2009

During a learning process, a human being is assumed to experience knowledge-based behaviors, rule-based behaviors, and skill-based behaviors sequentially if Rasmussen was right. If any psycho-physiological symptom to those different levels can be obtained, it can be useful as a measure whether a human being is fully trained and has gotten a skill in his work. Therefore, this study aimed to draw relationships between human performance measures and psycho-physiological measures while committing a computer-simulated pointing task by utilizing the power spectrum technique of EEG data, especially with the ratio of relative beta-to-alpha band power. The result showed that, during correct responses, the ratio came to stabilize as all the performance data went stable. However, response time was not a simple linear function of task difficulty level only, but a joint function of task characteristics as well as behavior levels. Comparing relative band power ratios from errors and correct responses, activated states of one's brain could be explained, and characteristics of the task could understood. To tell that of pointing task, correlations around C3, C4, P3, P4 and 01, 02 area were significant and high in correct response cases whereas most correlation coefficients went down in error cases standing for imbalance of psycho-motor functions. Though task difficulty was the only one factor that could influence on relative band power ratio with statistical significance, it should be comprehended to mean a different way of expression indicating task characteristics since at least error-some situation could be explained with the help of relative band power ratio that absolute band power failed.

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1317-1326
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• 1999

As the integration ratio and operation speed increase, it has become an important problem to estimate the dissipated power during the design procedure as a method to reduce the TTM(time to market). This paper proposed a prediction model to estimate the maximum dissipated power of a CMOS logic gate. This model uses a calculational method. It was formed by including the characteristics of MOSFETs of which a CMOS gate consists, the operational characteristics of the gate, and the characteristics of the input signals. As the modeling process, a maximum power estimation model for CMOS inverter was formed first, and then a conversion model to convert a multiple input CMOS gate into a corresponding CMOS inverter was proposed. Finally, the power model for inverter was applied to the converted result so that the model could be applied to a general CMOS gate. For experiment, several CMOS gates were designed in layout level by $0.6{\mu}m$ layout design rule. The result by comparing the calculated results with those from HSPICE simulations for the gates showed that the gate conversion model has within 5% of the relative error rate to the SPICE and the maximum power estimation model has within 10% of the relative error rate. Thus, the proposed models have sufficient accuracies. Also in calculation time, the proposed models was more than 30 times faster than SPICE simulation. Consequently, it can be said that the proposed model could be used efficiently to estimate the maximum dissipated power of a CMOS logic gate during the design procedure.