• Journal of electromagnetic engineering and science
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• 제16권1호
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• pp.57-65
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• 2016

In this paper, based on the mode analysis of four-conductor lines, the extended mixed-mode chain-parameters and S-parameters of four-conductor lines are estimated using current division factors. The extended mixed-mode chain-parameters of cascaded four-conductor lines are then obtained with mode conversion. And, the extended mixed-mode S-parameters of cascaded four-conductor lines can be predicted from the transformation of the extended chain-parameters. Compared to the extended mixed-mode S-parameters of four-conductor lines, the cross-mode S-parameters are induced in the extended mixed-mode S-parameters of cascaded four-conductor lines, due to the imbalanced current division factors of cascaded two sections. The generated cross-mode S-parameters make the equivalent different- and common-mode conductors not independent from each other again. In addition, a new mode conversion, which applies the imbalanced current division factors, between the extended mixed-mode S-parameters and standard S-parameters is also proposed in this paper. Finally, the validity of the proposed extended mixed-mode S-parameters and mode conversion is confirmed by a comparison of the simulated and estimated results of shielded cable.

• 대한전자공학회논문지TE
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• 제37권1호
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• pp.1-11
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• 2000

본 논문에서는 HEMT의 산란계수와 DC특성을 측정하여 모델링 변수들을 정확하게 추출하는 방법을 제안하였다, HEMT의 소신호 등가회로 모델링 변수들 중 extrinsic 직렬 저항은 측정한 DC특성을 이용하여 FUKUI 방법으로 구하였고, 다른 모델링 변수들은 HP 8510C Network Analyzer를 사용하여 여러 바이어스에서 측정한 S-parameter를 이용하여 변수 값을 결정하였다. 최적화 과정을 거쳐 얻은 등가 회로의 중요한 변수인 gm값은 실제 측정한 gm값과 0.078%오차만을 보인 반면, 제작자가 제공한 데이터를 이용하여 최적화하여 얻은 gm값은 실제 측정한 gm값과 175.38%나 오차를 보였다. 그러므로 반드시 정확하게 측정하여 얻은 초기 값을 가지고 정확한 변수를 측정할 수 있다는 것과 HEMT 모델링 변수들을 추출하는 과정을 자세하게 제시했다.

• 전자공학회논문지
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• 제49권11호
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• pp.205-210
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• 2012

본 논문에서는 RED 파라미터를 조정하여 차등화 서비스의 서비스 품질 관리의 성능을 고찰한다. 차등화 서비스는 CIR 혹은 PIR 같은 QoS 파라미터를 이용하여 특정 트래픽의 패킷들을 구분한다. 구분된 패킷을 표시하기 위해 코드 포인트가 사용되며 각각의 가상 큐에 입력된다. 코드 포인트에 따라서 각 가상 큐에는 다른 RED 파라미터 값들이 적용된다. 코드 포인트 값이 커질수록 엄격한 RED 파라미터 값들이 할당된다. RED 파라미터를 조정하여 서비스 품질을 관리 할 수 있음을 보이기 위해 본 논문은 간단한 2 색 표식을 갖는 타임 슬라이딩 윈도우의 정책 모델을 사용하였다. NS-2를 이용한 실험 결과, RED 파라미터를 조정하여 차등화 서비스의 서비스 품질이 효과적으로 관리됨을 확인하였다.

• Structural Engineering and Mechanics
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• 제69권4호
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• pp.361-369
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• 2019

The determination of Paris' law parameters based on crack growth experiments is an important procedure of fatigue life assessment. However, it is a challenging task because it involves various sources of uncertainty. This paper proposes a novel probabilistic method, termed the S-N Paris law (SNPL) method, to quantify the uncertainties underlying the Paris' law parameters, by finding the best estimates of their statistical parameters from the S-N curve data using a Bayesian approach. Through a series of steps, the SNPL method determines the statistical parameters (e.g., mean and standard deviation) of the Paris' law parameters that will maximize the likelihood of observing the given S-N data. Because the SNPL method is based on a Bayesian approach, the prior statistical parameters can be updated when additional S-N test data are available. Thus, information on the Paris' law parameters can be obtained with greater reliability. The proposed method is tested by applying it to S-N curves of 40H steel and 20G steel, and the corresponding analysis results are in good agreement with the experimental observations.

• 전기학회논문지
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• 제56권6호
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• pp.1105-1110
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• 2007

This paper describes an equivalent circuit modeling of 4-port connector system. A coupled transmission line was designed and fabricated, mimicking a 4-port connector system, and then S-parameters were measured using 4 port VNA (Vector Network Analyzer). The S-parameters from measurement and from Full-wave simulator coincided quite nice. By using these S parameters, an equivalent circuit parameters for a 4-port system was obtained. The time domain response from the equivalent circuit model matched to the signals, which was measured using TDR(Time Domain Reflectometry) meter. We were also convinced that there should be enough bandwidth to get a meaningful time domain result from Fourier inverse transformation of the S parameters. In addition, we applied the conversion algorithm to the 4-port connector system, which calculates the S-parameters of a 4 port system using the data from a 2-port VNA with the other ports open. Comparison of the two data, one from measurement and the other one from the conversion algorithm, was made in this manuscript.

• 한국전자파학회논문지
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• 제11권6호
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• pp.876-885
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• 2000

추가적인 DC 측정이나 반복 계산법 또는 최적화 방법에 의존하지 않고도, 정상적인 바이어스(Normal activebias) 조건에서 측정하 S-파라미터로부터 MESFET과 HEMT의 외부 기생 저항을 간단히 구할 수 있는 방법이 제시되었다. 이를 위해서 zero 바이어스 조건에서 측정한 Z-파라미터로부터 Rs와 Rd의 차이를 구할수 있다는 사실이 이용된다. 측정한 S-파라미터로부터 외부 기생 인덕터와 캐패시터의 효과를 제거하면, 내부 소자와 외부 기생 저항을 포함한 새로운 소자를 정의할 수 있다. 내부 소자의 Y-파라미터인 Yint,11과 Yint,12의 실수부 값이 이론적으로 0이라는 사실을 이용하여 S-, Y-, Z-파라미터 행렬간의 상화관계를 이용하여 기생 저항 값을 쉽게계산할수 있다. 제시된 방법으로 기생 저항들을 구하고, 이 결과를 이용하여 내부 소자 등가회로를 구한 후에 40GHz까지 S-파라미터를 계산한 결과, 측정된 S-파라미터와 잘 일치하였다.

• Animal Bioscience
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• 제34권6호
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• pp.949-956
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• 2021

Objective: This study was focused on the estimation of parameters of Wood's model and description of the lactation curve using the cows which were lactated over 24 months on the first lactation. Methods: The database included 1,333 pure-bred dairy Simmental primiparous cows which lactated for 24 months (732 days). The initial dataset entering the procedure of assessment of parameters of Wood's function included 35,826 milk yield records. Milk yield was recorded throughout lactation, with the earliest record taken on day 6 and the latest on day 1,348 of lactation. This dataset was used for the assessment of parameters a, b, c of Wood's model using the non-linear statistical procedure. These parameters were estimated for different length of lactation. The assessed parameters were used for calculation of some characteristics of lactation curves. Results: The lowest value of a parameter (15.2317) of Wood's model of lactation curve was found out in lactations up to 305 days long, contrary to b and c parameters which were highest in those lactations (0.1029 and 0.0015, respectively). The maximum value of a parameter (17.4329) was found out in lactations up to 640 days long, unlike b and c parameters which were minimal in those lactations (0.0603 and 0.0010, respectively). Conclusion: It can be concluded that the parameters of Wood's model and the shape of lactation curve are changing with the growing number of milk yield records. Also, the assessed parameters revealed a significant milk production potential after 305 days of lactation.

• Journal of Periodontal and Implant Science
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• 제49권2호
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• pp.105-113
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• 2019

Purpose: An unresolved inflammatory state contributes to the pathogenesis of periodontal disease and metabolic syndrome (MetS). Therefore, the purpose of this study was to evaluate the role of lipoxin A4 (LXA4), a proresolving lipid mediator, in the association between periodontal disease and MetS. Methods: Sixty-seven patients with MetS and 65 patients without MetS were included in the study. Sociodemographic information was obtained via a questionnaire, and detailed medical diagnoses were made. Periodontal parameters (plaque index [PI], gingival index [GI], probing pocket depth [PD], and clinical attachment level [CAL]) and metabolic parameters were measured, and serum LXA4 levels were determined. The associations among MetS, periodontal parameters, and serum LX levels were evaluated by adjusted multivariate linear regression analyses. Results: Patients with MetS were older and had a higher body mass index than patients without MetS. Periodontal parameters (PI, GI, PD, and CAL) were higher in patients with MetS than in those without MetS. Serum LXA4 levels were higher in patients without MetS. Multivariate linear regression analysis indicated a positive association between MetS and periodontal parameters (PD and CAL). Negative associations were established between MetS and LXA4 levels, and between LXA4 and periodontal parameters (PI, PD, and CAL). Conclusions: The presence of higher values of periodontal parameters in patients with MetS and the negative relationship of LXA4 with MetS and periodontal disease may support the protective role of proresolving lipid mediators in the association between periodontal disease and MetS.

• 한국전자파학회논문지
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• 제25권8호
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• pp.808-820
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• 2014

본 논문에서는 10-dB 감쇠기 및 상용 패키지 된 MMIC 능동소자를 이용하여 구성된 증폭기, 2가지의 온-웨이퍼(on-wafer)형 DUT(Device-Under Test)를 구성하고, 이들의 잡음파라미터를 8-port 회로망을 이용하여 추출하는 방법을 제시하였다. 제작된 10-dB 감쇠기의 경우 수동소자이기 때문에, 이것의 S-파라미터를 측정하여 얻을 경우, 이것의 잡음파라미터를 알 수 있고, 또한 증폭기의 경우 이것의 잡음파라미터가 datasheet에 있다. 따라서 제안한 방법을 이용한 잡음파라미터 측정 결과에 대한 평가를 용이하게 할 수 있다. 기존 저자들에 의하여 발표된 6-포트회로망을 확장한 8-포트회로망을 이용한 잡음파라미터 측정은 사용된 8-포트회로망의 S-파라미터를 필요로 하는데, 동축형 DUT에 국한된다. 온-웨이퍼 프로브가 8-포트회로망에 삽입될 경우, 8-포트회로망의 S-파라미터 측정은 이종 형태의 커넥터를 갖는 8-포트회로망이 된다. 본 논문에서는 회로망 분석기(Network analyzer)의 Smart-cal 기능을 이용하여 8-포트회로망의 S-파라미터를 추출하였다. 측정된 잡음파라미터는 최소잡음지수, $NF_{min}$ 경우, 예상된 결과에 대하여 약 ${\pm}0.2dB$의 오차를 보인다. 다른 잡음파라미터는 주파수에 따라 예상된 결과와 근접하게 일치하는 결과를 보여주고 있다.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.344-353
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• 2000

Recent mechatronics technology is the most appropriate high technology in the agricultural application to save repetitious labor. Cow's body parameters were measured by traditional several measurer. Image processing technology was used to measure automatically their parameters to reduce lots of labor and time. The parameters were measured form a small model cow, which is easily measured, instead to a real cow. The image processing system designed and built for this project was composed of a Pentium PC, and TV frame card two cameras which were located on side and top of model cow. 11 parameters of cow's body were measured and the error between real data and the data by image processing was less than 10%. Based on the results of this research the parameters of a real cow could be measured in the future.