• 한국군사과학기술학회지
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• 제6권4호
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• pp.80-88
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• 2003

Radar signal simulation is increasingly gaining in importance according as modem radar systems are more complex. Although computer performance has been advanced, it is difficult to implement the real-time simulation because the detailed model for the radar is necessary to get the desired accuracy. In order to achieve real time operation, we propose radar signal generation technique using ambiguity function, Instead of wellknown correlation method. The ambiguity function is the mathematical modeling of the signal processing procedure which is a simulation section to require the most computations.

• 한국전자파학회논문지
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• 제23권3호
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• pp.410-413
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• 2012

2차원 레이다 간섭계에서 표적의 공간 도달 각도를 추정하는 방법 중에서 1차원 알고리즘과 디지털 빔 포밍알고리즘, 위상차의 최소 자승 오차 알고리즘들의 각도 모호성 해소 성능을 비교한다. 위상 비교 모노 펄스 알고리즘의 경우, 2차원 레이다 간섭계에 적용하기 위해 방위각 방향과 고각 방향으로 각각 적용하였다. 성능 비교를 위해 Monte carlo 시뮬레이션 방법을 이용하여 2차원 레이다 간섭계에서 각도 추정 알고리즘 별 각도 모호성 해소 확률과 수행 시간을 비교하였다. 각도 모호성 해소 확률과 수행 시간을 고려할 때 위 여러 방법 중에서 위상 비교 모노 펄스 알고리즘이 실시간 신호 처리 분야에 가장 효율적임을 보여준다.

• Korean Journal of Geomatics
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• 제3권2호
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• pp.129-140
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• 2004

This paper addresses solutions th the challenges of carrier phase integer ambiguity resolution and cycle slip detection/identification, for maintaining high accuracy of an integrated GPS/Pseudolite/INS system. Such a hybrid positioning and navigation system is an augmentation of standard GPS/INS systems in localized areas. To achieve the goal of high accuracy, the carrier phase measurements with correctly estimated integer ambiguities must be utilized to update the system integration filter's states. The contribution presents an effective approach to increase the reliability and speed of integer ambiguity resolution through using pseudolite and INS measurements, with special emphasis on reducing the ambiguity search space. In addition, an algorithm which can effectively detect and correct the cycle slips is described as well. The algorithm utilizes additional position information provided by the INS, and applies a statistical technique known as th cumulative-sun (CUSUM) test that is very sensitive to abrupt changes of mean values. Results of simulation studies and field tests indicate that the algorithms are performed pretty well, so that the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.

• 대한간호학회지
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• 제31권4호
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• pp.571-583
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• 2001

Purpose: The purpose of this study was to examine the levels of burnout experienced by Korean hospital nurses (N=198), and to identify predictors of their nursing outcomes such as job performance, work satisfaction, and productivity. Method: Hierarchical multiple regression was used to identify predictors of each nursing outcomes. Included predictors were nurses' general characteristics, work- related characteristics (role stress and perceived control), and burnout. Results: Korean nurses experienced higher levels of burnout compared to the cutoffs suggested by Maslach and Jackson (1986) and to those in the USA. For each nursing outcome, predictor variables explained 39% of the variance in role performance, 30% of the variance in work satisfaction, and 38% of variance in productivity. Higher personal accomplishment, lower role ambiguity, being staff nurses, and lower emotional exhaustion were related to higher job performance, and higher productivity. Lower role conflict and role ambiguity were also related to higher work satisfaction. Conclusion: Based on the findings of this study, managemental interventions for nurses to reduce their burnout experience are needed. Further study in this area is warranted.

• International Journal of Aeronautical and Space Sciences
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• 제5권2호
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• pp.1-8
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• 2004

Real-Time Kinematic GPS positioning is widely used for many applications.Resolving ambiguities is the key to precise positioning. Integer ambiguity resolution isthe process of resolving the unknown cycle ambiguities of double difference carrierphase data as integers. Two important issues of resolving are efficiency andreliability. In the conventional search techniques, we generally used chi-squarerandom variables for decision variables. Mathematically, a chi-square random variableis the sum of mutually independent, squared zero-mean unit-variance normal(Gaussian) random variables. With this base knowledge, we can separate decisionvariables to several normal random variables. We showed it with related equationsand conceptual diagrams. With this separation, we can improve the computationalefficiency of the process without losing the needed performance. If we averageseparated normal random variables sequentially, averaged values are also normalrandom variables. So we can use them as decision variables, which prevent from asudden increase of some decision variable. With the method using averaged decisionvalues, we can get the solution more quicklv and more reliably.To verify the performance of our proposed algorithm, we conducted simulations.We used some visual diagrams that are useful for intuitional approach. We analyzedthe performance of the proposed algorithm and compared it to the conventionalmethods.

• 한국군사과학기술학회지
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• 제14권4호
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• pp.590-597
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• 2011

The IDRS provides detection, classification and bearing/range estimation by performing wavefront curvature analysis on an intercepted active transmission from target. Especially, a estimate of the target bearing/range that significantly affects the optimal operation of own submarine is required. Target bearing/range can be estimated by wavefront curvature ranging which use the difference of time arrival at sensors. But estimation ambiguity occur in bearing/range estimation due to a number of peaks caused by high center frequency and limited bandwidth of the intercepted active transmission and distortion caused by noise. As a result the bearing/range estimation performance is degraded. To estimate target bearing/range correctly, bearing/range estimation method that eliminate estimation ambiguity is required. In this paper, therefore, for wavefront curvature ranging, NLS cost function with curve fitting method is proposed, which provide robust bearing/range estimation performance by eliminating estimation ambiguity. Through simulation the performance of the proposed bearing/range estimation methods are verified.

• Journal of Information Technology Applications and Management
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• 제23권2호
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• pp.113-141
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• 2016

This study identifies and validates the factors that affect sales performance of salespersons in the business software industry. In the study, in order to measure the dependent variable (performance of the salesperson) more comprehensively, multiple items are utilized and both outcome and behavior indicators are used. Independent variables are identified based on the classification of Verbeke et al. [(2011] including sales related knowledge, degree of adaptiveness, role ambiguity, and work engagement. Results of the hypotheses testing show that 'sales related knowledge' and 'work engagement' are statistically significant factors, but 'degree of adaptiveness' and 'role ambiguity' are not. This study has a few limitations and future research direction to overcome the limitation is suggested : use of both perceptions of the salesperson and objective measures in measuring the related variables; study including cognitive ability; analyses of the factors across various types of software companies; and analyses of the factors on the team level.

• 한국직업건강간호학회지
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• 제27권2호
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• pp.77-88
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• 2018

Purpose: This study aimed to investigate the degree of role conflict and its ambiguity, and fatigue in clinical nurses and to analyze the effect of these on their self-resilience in order to provide fundamental data for improving their working environment after the Middle East Respiratory Syndrome outbreak. Methods: After the collection of data from 258 clinical nurses in five general hospitals, t-test, ANOVA, Pearson's correlation coefficient, and multiple regression were performed using IBM SPSS Statistics 20.0. Results: A significant positive correlation was found between nurses' role conflict and ambiguity and fatigue; while a negative correlation was found between nurses' role conflict and ambiguity and self-resilience. A significant negative correlation was found between fatigue and self-resilience. According to the study results, the factor that affected clinical nurses' self-resilience the most was role conflict and its ambiguity, followed by marital status, fatigue, educational level, religion, and related tasks, which together accounted for 38% of self-resilience in clinical nurses. Conclusion: To improve weaknesses in nursing care after the Middle East Respiratory Syndrome outbreak, the scope of nursing care was changed upon the expansion of integrated nursing and care-giving services. Therefore, in the rapidly changing environment of nursing, policies to improve nursing performance, as well as successful reaction capability, are suggested.

• 대한토목학회논문집
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• 제34권1호
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• pp.341-353
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• 2014

GPS 반송파를 사용하여 센티미터 수준 정확도의 동적 측위를 위해서는 반송파 관측데이터에 포함하고 있는 미지정수를 결정하여 정밀한 기하거리로 환산하는 것이 필수적이다. 본 논문에서는 GPS에 의한 실시간 구조물 모니터링에 효율적으로 적용가능한 반송파 관측데이터 순간미지정수 결정 성능향상을 위한 알고리즘을 연구하였다. 이를 위하여 구조물에 설치한 GPS 수신기 이동 범위와 그 네트워크를 수학적으로 모형화하고 '정수제약 최소제곱법'을 통해 정확한 위치를 추정하는 절차를 제안하였다. 이 절차에는 추정해의 신뢰성 향상을 위해 실수해의 과대오차 최소화에 필요한 품질제어와 기하적 구속조건을 이용한 미지정수 타당성 검정을 포함하고 있다. 제안된 순간미지정수 결정절차를 과학기술용 계산용 소프트웨어인 MATLAB에 의해 실시간 적용 가능하도록 구현하고 장대교량에 해당하는 사장교 현장 관측데이터를 처리하여, 그 성능을 미지정수결정 성공률, 통계모형의 영향 그리고 연산시간에 대해 분석하고 결과를 요약하였다.

• Journal of Positioning, Navigation, and Timing
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• 제10권3호
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• pp.159-168
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• 2021

Precise Point Positioning-Real Time Kinematic (PPP-RTK) is an improved PPP method that provides the user receiver with satellite code and phase bias correction information in addition to the satellite orbit and clock, thus enabling single-receiver ambiguity resolution. Single station PPP-RTK concept is special case of PPP-RTK in that corrections are computed, instead of a network, by only one single GNSS receiver. This study is performed to experimentally verify the positioning accuracy performance of single baseline RTK level by a user who utilizes correction for a single station PPP-RTK using dual frequencies. As an experimental result, the horizontal and vertical 95% accuracy was 2.2 cm, 4.4 cm, respectively, which verify the same performance as the single baseline RTK.