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Generalized BER Expression of MPSK in the Presence of Phase Error
Yeonsoo Jang,Dongweon Yoon,Sang-Kon Lee IEEE 2013 IEEE communications letters Vol.17 No.12
<P>In this letter, we derive an exact and general closed-form expression for the bit error rate (BER) of Gray coded M-ary phase shift keying (MPSK) in the presence of a fixed phase error. We also propose a very simple and tight approximate expression from the derived exact expression. To validate the exactness of the proposed exact and general expression and the tightness of the proposed approximation, we compare the results obtained from the proposed expressions with those from computer simulations. We also present the average BER results of MPSK for random phase errors caused by phase-locked loop or imperfect channel estimation by using the derived expressions.</P>
Multipath effect on radar detection of nonfluctuating targets
Yeonsoo Jang,Hyeongyong Lim,Dongweon Yoon IEEE 2015 IEEE transactions on aerospace and electronic syst Vol.51 No.1
<P>We derive the probability density function (PDF) of a received radar signal in the presence of multipath when a reflecting surface with an arbitrary reflection coefficient exists. Using the PDF, we present the detection probabilities of nonfluctuating targets for various reflection coefficients and analyze the multipath effect on radar detection.</P>
Development and Validation of the Non-Alcoholic Fatty Liver Disease Self-Management Questionnaire
( Yeonsoo Jang ),( Oh Young Kwon ),( Ji Yea Lee ),( Seung Up Kim ) 대한간학회 2020 춘·추계 학술대회 (KASL) Vol.2020 No.1
Aims: Non-alcoholic fatty liver disease (NAFLD) is one of common causes of chronic liver disease. The prevalence of NAFLD is increasing with other weight related disease such as obesity, diabetes and metabolic diseases. Self-management is known as a crucial key to improve health outcomes of patients with chronic diseases including NAFLD. However, there is no instrument to measure the level of self-management for patients with NAFLD. This study aims to develop and validate NAFLD self-management questionnaires. Methods: A 23-item of Non-Alcoholic Fatty Liver Disease Self-Management Questionnaire (NAFLD-SMQ) was initially developed after theoretical and literature review by three phases: (1) Items generation; (2) Evaluation of the items; and (3) Psychometric evaluation. Data collection was from April-November in 2019. Participants were 155 individuals recruiting from S hospital in South Korea. The questionnaire was tested by the construct validity using for exploratory factor analysis. Results: Items of the questionnaire were generated based on guideline for patients with NAFLD and the Individual and Family Self-Management Theory. A six-factor was extracted from construct validation using exploratory factor analysis: lifestyle management, drinking management, sleep management, health-supplements management, medical treatment compliance, and family support. These factors accounted for 66.2% of total variation, and have an eigenvalue higher than 1 in the scale. The corrected item-total correlation coefficients ranged 0.33-0.59, and all items were significantly correlated with the total score. Cronbach’s alpha of the total items was 0.87. Conclusions: The NAFLD-SMQ was developed through three phases, and the results of EFA were determined to be valid and reliable. Healthcare providers should assess and evaluate the level of self-management to provide tailored interventions based on their care needs. This instrument would provide useful information for healthcare providers who assess self-management level for individuals with NAFLD. In addition, it may be used as the indicator of health outcomes in this population.
모노펄스 레이더에 대한 전파왜곡 시스템의 요구 성능 분석
장연수(Yeonsoo Jang),김기백(Ghiback Kim),박진태(Jintae Park),이창훈(Changhoon Lee) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.6
모노펄스 레이더에 대한 효과적인 재밍은 전파를 왜곡시키는 것이다. 그 중 대표적인 전파왜곡 기법은 두 개의 송신기를 이용하는 크로스 아이 기법이다. 크로스 아이 기법은 모노펄스 레이더의 구현 구조에 관계없이 각도를 기만할 수 있지만, 충분한 각도기만 효과를 갖기 위해서는 두 송신기의 위상 및 진폭 정확도가 확보되어야 한다. 이러한 위상 및 진폭 정확도는 전파왜곡 시스템을 구현하는데 있어서 핵심적인 요구 성능 파라미터이고, 목표로 하는 각도 오차에 따라 그 요구값이 달라진다. 본 논문에서는 목표하는 각도 오차에 따라 필요한 최소 위상차 및 진폭비를 수식으로 유도하고 그 결과를 분석한다. One of the effective jamming methods to disturb monopulse radars is a wavefront distortion. Most well-known wavefront distortion is the cross eye technique which uses two transmitters. The cross eye can make angle error regardless of monopulse radar structure but high accuracies of phase and amplitude between two transmitters should be needed to make large angle error. Thus, the accuracies of phase and amplitude are essentially required performance parameters for implementation of wavefront distortion systems and the required values of accuracy is dependant on amount of angle error. In this paper, we derive expressions for minimum required values of phase difference and amplitude ratio according to amount of angle error and analyze the results.