TWR 기반 군집 협업측위 시스템의 오차 전파 분석

임정민,이창은,성태경,Lim, Jeong-Min,Lee, Chang-Eun,Sung, Tae-Kyung 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.9

Alternative radio-navigation technologies aim at providing continuous navigation solution even if one cannot use GNSS (Global Navigation Satellite System). In shadowing region such as indoor environment, GNSS signal is no longer available and the alternative navigation system should be used together with GNSS to provide seamless positioning. For soldiers in battlefield where GNSS signal is jammed or in street battle, the alternative navigation system should work without positioning infrastructure. Moreover, the radio-navigation system should have scalability as well as high accuracy performance. This paper presents a TWR (Two-Way-Ranging)-based cooperative positioning system (CPS) that does not require location infrastructure. It is assumed that some members of CPS can obtain GNSS-based position and they are called mobile anchors. Other members unable to receive GNSS signal compute their position using TWR measurements with mobile anchors and neighboring members. Error propagation in CPS is analytically studied in this paper. Error budget for TWR measurements is modeled first. Next, location error propagation in CPS is derived in terms of range errors. To represent the location error propagation in the CPS, Location Error Propagation Indicator (LEPI) is proposed in this paper. Simulation results show that location error of tags in CPS is mainly influenced by the number of hops from anchors to the tag to be positioned as well as the network geometry of CPS.

장애인연금제도가 필수재 및 장애추가비용 지출에 미치는 영향: 성향점수매칭과 이중차이분석 활용

임정민(Jeong Min Lim) 한국장애인복지학회 2024 한국장애인복지학 Vol.63 No.-

본 연구의 목적은 장애인연금제도가 필수적인 생활비 부담을 완화시키는지, 그리고 고소득층 중증장애인가구와의 추가비용지출 격차를 감소시키는지를 살펴보는 것이다. 이러한 목적과 관련하여 장애인삶패널조사 1차(2018년)와 3차(2020년) 데이터를 활용하였고, 성향점수매칭과 이중차이분석을 수행하였다. 단순이중차이 분석결과, 중증장애인가구는 장애인연금 수급에도 불구하고 필수재 지출 부담 수준이 높게 나타났으며, 일부 비목에서만 긍정적 효과가 나타났다. 더불어 본 연구는 소득 계층에 따라 장애추가비용 지출 격차가 더욱 확대되는 결과를 도출함으로써 장애인연금 수급가구의 경제적 복지 수준이 낮음을 발견하였다. 한편 이중차이회귀분석 결과, 장애인연금제도의 정책적 효과는 없는 것으로 나타났다. 본 연구는 그동안 간과되어왔던 장애인연금을 수급하는 중증장애인가구의 소비지출 실태를 드러내고, 다음과 같이 정책적 제언을 하고자 한다. 먼저 장애인연금제도의 기초급여와 부가급여가 적절한 수준에서 제공되고 있는지에 대한 논의가 필요하다. 다음으로 장애인연금의 지급 대상자 범위를 확대하여 불평등을 최소화하고, 보다 공정한 지원체계를 구축하여야 할 것이다. 이와 같은 정책적 개입은 중증장애인가구의 소비를 변화시켜 경제적 복지 수준의 향상을 가져올 것으로 예상된다. The purpose of this study is to examine the impact of disability pension on alleviating the financial burden associated with essential expenses and narrowing the gap in disability costs between high-income households with severely disabled members and others in Korea. In pursuit of these objectives, Propensity score matching (PSM) and Difference-in-Differences analysis (DID) analysis were conducted to utilize data from the disability life panel survey 1st (2018) and 3rd (2020). As a result, despite receiving disability pensions, households with severely disabled members experienced a high burden in essential expenses. Moreover, the study revealed that they faced the gap in additional disability costs based on their income class. Thus, policy interventions are required to increase the disability pension amount and extend the eligible recipients.

열수송관에서 pH에 따른 부식생성물이 탄소강의 부식에 미치는 영향

임정민(Jeong Min Lim),소윤식(Yoon Sik So),김우철(Woo Cheol Kim),김정구(Jung Gu Kim) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

pH of district heating water is controlled to prevent a fracture of pipeline by corrosion. However, corrosion behavior of carbon steel is changed by corrosion products. Therefore, in this study, the corrosion behavior of long-term used heat transport pipeline was evaluated as variable of pH in a simulated district heating water. The corrosion behavior was evaluated after accelerating the 10 years corrosion using a galvanostatic test according to pH 5, 7, 9 and 11. As a result, localized corrosion was occurred in pH 5 and 11, and uniform corrosion was shown in pH 7 and 9. In pH 9 and 11, magnetite was formed on the surface of specimen. The high electrical conductivity of magnetite induces galvanic corrosion between carbon steel and magnetite, resulting in localized corrosion. At pH 7 and 9, the corrosion rate was the lowest at pH 9. Therefore, pH of heating water should be managed not to be lower than 5 or higher than 11. Also, it is best to maintain a pH of 9 for a long-term use of the pipeline.

약 신호 환경에서의 Assisted-Galileo 신호 획득 성능 분석

임정민(Jeong-Min Lim),박지원(Ji-Won Park),성태경(Tae-Kyung Sung) 제어로봇시스템학회 2013 제어·로봇·시스템학회 논문지 Vol.19 No.7

EU’s Galileo project is a market-based GNSS (Global Navigation Satellite System) that is under development. It is expected that Galileo will provide the positioning services based on new technologies in 2020s. Because Galileo E1 signal for OS (Open Service) shares the same center frequency with GPS L1 C/A signal, CBOC (Composite Binary Offset Carrier) modulation scheme is used in the E1 signal to guarantee interoperability between two systems. With E1 signal consisting of a data channel and a pilot channel at the same frequency band, there exist several options in designing signal acquisition for Assisted-Galileo receivers. Furthermore, compared to SNR worksheet of Assisted-GPS, some factors should be examined in Assisted-Galileo due to different correlation profile and code length of E1 signal. This paper presents SNR worksheets of Galileo E1 signals in E1-B and E1-C channel. Three implementation losses that are quite different from GPS are mainly analyzed in establishing SNR worksheets. In the worksheet, hybrid long integration of 1.5s is considered to acquire weak signal less than -150dBm. Simulation results show that the final SNR of E1-B signal with -150dBm is 19.4dB and that of E1-C signal is 25.2dB. Comparison of relative computation shows that E1-B channel is more profitable to acquire the strongest signal in weak signal environment. With information from the first satellite signal acquisition, fast acquisition of the weak signal around -155dBm can be performed with E1-C signal in the subsequent satellites.

Geometry 정보와 오차 공분산을 이용한 협업 측위 오차 모델링

임정민(Jeong-Min Lim),오정훈(Jeong-Hun Oh),유상훈(Sang-Hoon Yoo),이창은(Chang-Eun Lee),성태경(Tae-Kyung Sung) 대한전기학회 2013 대한전기학회 학술대회 논문집 Vol.2013 No.10

열수송관에서 pH에 따른 부식생성물이 탄소강의 부식에 미치는 영향

임정민(Jeong Min Lim),소윤식(Yoon Sik So),김우철(Woo Cheol Kim),김정구(Jung Gu Kim) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

pH of district heating water is controlled to prevent a fracture of pipeline by corrosion. However, corrosion behavior of carbon steel is changed by corrosion products. Therefore, in this study, the corrosion behavior of long-term used heat transport pipeline was evaluated as variable of pH in a simulated district heating water. The corrosion behavior was evaluated after accelerating the 10 years corrosion using a galvanostatic test according to pH 5, 7, 9 and 11. As a result, localized corrosion was occurred in pH 5 and 11, and uniform corrosion was shown in pH 7 and 9. In pH 9 and 11, magnetite was formed on the surface of specimen. The high electrical conductivity of magnetite induces galvanic corrosion between carbon steel and magnetite, resulting in localized corrosion. At pH 7 and 9, the corrosion rate was the lowest at pH 9. Therefore, pH of heating water should be managed not to be lower than 5 or higher than 11. Also, it is best to maintain a pH of 9 for a long-term use of the pipeline.

간호대학생의 인성, 긍정심리자본이 학업탄력성에 미치는 영향

임정민 ( Jeong-min Lim ) 한국산업융합학회 2023 한국산업융합학회 논문집 Vol.26 No.6

The purpose of this study was to investigate the relationship between personality, positive psychological capital, and academic resilience of nursing students and to identify the factors affecting academic resilience of nursing students. Data were collected from 199 nursing students in their first and second year at C nursing college in M-gun, J-do, and a survey was conducted from July 10 to July 28, 2023. The collected data were analyzed using descriptive statistics, t-test, one-way ANOVA, Scheffe test, Pearsons correlation coefficient, Stepwise multiple regression analysis was conducted. Personality had a significant positive correlation with positive psychological capital(r=.62, p<.001) and academic resilience(r=.68, p<.001), and positive psychological capital had a significant positive correlation with academic resilience(r=.79, p<.001). The major factor influencing the academic resilience of nursing students was positive psychological capital, followed by personality, interpersonal relationship, and college life satisfaction, and their total explanatory power was 72% (F=102.85, p<.001). Based on the results of this study, it is necessary to develop an educational program that can increase positive psychological capital in order to strengthen the academic resilience of nursing students, and efforts should be made to introduce and manage it in the nursing curriculum.

TWR 기반 군집 협업측위 시스템의 오차 전파 분석

임정민(Jeong-Min Lim),이창은(Chang-Eun Lee),성태경(Tae-Kyung Sung) 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.4

Alternative radio-navigation technologies aim at providing continuous navigation solution even if one cannot use GNSS (Global Navigation Satellite System). In shadowing region such as indoor environment, GNSS signal is no longer available and the alternative navigation system should be used together with GNSS to provide seamless positioning. For soldiers in battlefield where GNSS signal is jammed or in street battle, the alternative navigation system should work without positioning infrastructure. Moreover, the radio-navigation system should have scalability as well as high accuracy performance. This paper presents a TWR (Two-Way-Ranging)-based cooperative positioning system (CPS) that does not require location infrastructure. It is assumed that some members of CPS can obtain GNSS-based position and they are called mobile anchors. Other members unable to receive GNSS signal compute their position using TWR measurements with mobile anchors and neighboring members. Error propagation in CPS is analytically studied in this paper. Error budget for TWR measurements is modeled first. Next, location error propagation in CPS is derived in terms of range errors. To represent the location error propagation in the CPS, Location Error Propagation Indicator (LEPI) is proposed in this paper. Simulation results show that location error of tags in CPS is mainly influenced by the number of hops from anchors to the tag to be positioned as well as the network geometry of CPS.

Geometry 정보와 오차 공분산을 이용한 협업 측위 오차 모델링

임정민(Jeong-Min Lim),오정훈(Jeong-Hun Oh),유상훈(Sang-Hoon Yoo),이창은(Chang-Eun Lee),성태경(Tae-Kyung Sung) 대한전기학회 2013 정보 및 제어 심포지엄 논문집 Vol.2013 No.10

실내 비행 로봇을 위한 WPAN 기반 자가 측위 시스템 개발

임정민(Jeong-Min Lim),정원민(Won-Min Jeong),성태경(Tae-Kyung Sung) 제어로봇시스템학회 2015 제어·로봇·시스템학회 논문지 Vol.21 No.5

As flying robots are becoming popular, there are increased needs to use themforsuch purposes as parcel delivery, serving in restaurants, and stage performances. To control flying robots such as quad copters, localization is essential. In order to properly position flying robots, many techniques are in development, including IR (infra-red)-based systemswhich catch markers on a flying robot in order that it can position itself. However, this technique demonstrates only short coverage. Furthermore, localization from inertial sensors diverges as time passes. For this reason, this paper suggests a TWR (two-way ranging) based positioning technique. Despite the weaknesses in currently available TWR system, this paper suggests a self-positioning and outlier detection technique in order to provide reliable position information with a faster update rate. The self-positioning system sends a shorter message which reduces wireless traffic. By detecting and removing outlier measurements, a positioning result with better accuracy is acquired. Finally, this paper shows that the suggesting system detects outlierssequentially from less than half the number of anchors in localization system according to the degree of outlier in measurement and the noise level. By performing an outlier algorithm, better positioning accuracy is acquired as shown in the experimental result.