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뇌기반 진화적 접근법에 따른 과학 야외학습이 초등학생들의 흥미와 성취도에 미치는 영향
박형민 ( Hyoungmin Park ),김재영 ( Jaeyoung Kim ),임채성 ( Chaeseong Lim ) 한국초등과학교육학회 2015 초등과학교육 Vol.34 No.2
This study analyzed the effects of science outdoor activity applying a Brain-Based Evolutionary (ABC-DEF) approach on elementary school students`` interest and academic achievement. Samples of the study were composed of 3 classes of 67 sixth graders in Seoul, Korea. Unit of ‘Ecosystem and Environment’ was selected as a object of the research. Textbook- and teachers`` guidebook-based instruction was implemented in comparison group, brain-based evolutionary approach within classroom in experimental group A, and science outdoor learning by a brain-based evolutionary approach in experimental group B. In order to analyze the quantitative differences of students`` interests and achievements, three tests of ‘General Science Attitudes’, ‘Applied Unit-Related Interests’, and ‘Applied Unit-Related Achievement’ were administered to the students. To find out the characteristics which would not be apparently revealed by quantitative tests, qualitative data such as portfolios, daily records of classroom work, and interview were also analyzed. The major results of the study are as follows. First, for post-test of interest, a statistically significant difference between comparison group and experimental group B was found. Especially, the ‘interests about biology learning’ factor, when analyzed by each item, was significant in two questions. Results of interviews the students showed that whether the presence or absence of outdoor learning experience influenced most on their interests about the topic. Second, for post-test of achievement, the difference among 3 groups according to high, middle, and low levels of post-interest was not statistically significant, but the groups of higher scores in post-interest tends to have higher scores in post-achievement. It can be inferred that outdoor learning by a brain-based evolutionary approach increases students`` situational interests about leaning topic. On the basis of the results, the implications for the research in science education and the teaching and learning in school are discussed.
소형 유도탄을 위한 고이득 관측기 적용 구동 강건 제어기 설계
이형민(Hyoungmin Lee),박치형(Chihyoung Park),박은주(Eunjoo Park),정승환(Seunghwan Jung),서석훈(Suhkhoon Suh),조승환(Seunghwan Cho) 한국추진공학회 2015 한국추진공학회 학술대회논문집 Vol.2015 No.11
소형 유도탄을 위한 구동 강건 제어기 설계 기법 및 고이득 관측기 기반의 제어기법이 제안된다. 유도탄의 비행 시 발생하는 외란추력, 마찰계수 등의 불확정성을 갖는 파라미터들은 시스템의 구동제어 성능에 직접적인 영향을 준다. 이러한 시스템의 불확정성을 효과적으로 추정할 수 있는 고이득 관측기를 통해 외란이 추정되며 추정된 외란이 제어입력에 전향제어 방식으로 보상된다. Simulink 기반의 시뮬레이션을 통해 제안된 방식이 구동 강건 제어기에 적합함 입증하였다. This study Presents a robust actuation controller for undersize missile and High Gain Observer-based control. During flight of a missile, the force disturbance and mecheanical parameter variations such as the friction coefficient gives a direct influence on the actuation control performance of missile. The system uncertainty caused by the force disturbance and mechanical parameter variations is estimated through a high gain observer and compensated by a feedforward manner. For suitability of this design, it is proved that the robust actuation controller using simulation based on Similink.
박형민(Hyoungmin Park),심규석(Kyuseok Shim),장원준(WonjunChang) 한국정보과학회 2006 한국정보과학회 학술발표논문집 Vol.33 No.2C
실제 데이터들은 압축이 필요할 정도로 큰 경우가 종종 있다. 일반적인 구조론적 데이터 압축 방법은 테이블을 긴 바이트 스트링으로 취급하여 바이트 레벨에서 압축을 시도한다. 이런 경우에 보통 압축의 효율과 검색의 용이성(특정 레코드의 애프리뷰트 값을 찾아내기 위해 압축을 풀어야 하는 부분의 크기)사이에 교환관계가 발생한다. 이런 점에서 검색을 위해 압축을 풀 필요가 없는 의미론적 압축 방법이 주목을 받고 있다. 이 논문에서는 기존의 파시클(fascicle) 알고리즘을 개선하는 새로운 의미론적 알고리즘을 제시하고 실험을 통하여 제안된 알고리즘의 우수성을 입증한다.
Feasibility Study on Integration of SSR Correction into Network RTK to Provide More Robust Service
Lim, Cheol-Soon,Park, Byungwoon,Kim, Dong-Uk,Kee, Chang-Don,Park, Kwan-Dong,Seo, Seungwoo,So, Hyoungmin,Park, Junpyo The Institute of Positioning 2018 Journal of Positioning, Navigation, and Timing Vol.7 No.4
Network RTK is a highly practical technology that can provide high positioning accuracy at levels between cm~dm regardless of user location in the network by extending the available range of RTK using reference station network. In particular, unlike other carrier-based positioning techniques such as PPP, users are able to acquire high-accuracy positions within a short initialization time of a few or tens of seconds, which increases its value as a future navigation system. However, corrections must be continuously received to maintain a high level of positioning accuracy, and when a time delay of more than 30 seconds occurs, the accuracy may be reduced to the code-based positioning level of meters. In case of SSR, which is currently in the process of standardization for PPP service, the corrections by each error source are transmitted in different transmission intervals, and the rate of change of each correction is transmitted together to compensate the time delay. Using these features of SSR correction is expected to reduce the performance degradation even if users do not receive the network RTK corrections for more than 30 seconds. In this paper, the simulation data were generated from 5 domestic reference stations in Gunwi, Yeongdoek, Daegu, Gimcheon, and Yecheon, and the network RTK and SSR corrections were generated for the corresponding data and applied to the simulation data from Cheongsong reference station, assumed as the user. As a result of the experiment assuming 30 seconds of missing data, the positioning performance compensating for time delay by SSR was analyzed to be horizontal RMS (about 5 cm) and vertical RMS (about 8 cm), and the 95% error was 8.7 cm horizontal and 1cm vertical. This is a significant amount when compared to the horizontal and vertical RMS of 0.3 cm and 0.6 cm, respectively, for Network RTK without time delay for the same data, but is considerably smaller compared to the 0.5 ~ 1 m accuracy level of DGPS or SBAS. Therefore, maintaining Network RTK mode using SSR rather than switching to code-based DGPS or SBAS mode due to failure to receive the network RTK corrections for 30 seconds is considered to be favorable in terms of maintaining position accuracy and recovering performance by quickly resolving the integer ambiguity when the communication channel is recovered.
Park, Sang-Min,Kim, Gang-Un,Kim, Ho-Joong,Kim, Hyoungmin,Chang, Bong-Soon,Lee, Choon-Ki,Yeom, Jin S. Elsevier 2019 SPINE JOURNAL Vol.19 No.5
<P><B>Abstract</B></P> <P><B>BACKGROUND CONTEXT</B></P> <P>Physical activity, such as muscle strengthening and aerobic exercise, has been found to be effective for low back pain (LBP). However, the association between weekly walking duration and LBP in the general population remains poorly understood.</P> <P><B>OBJECT</B></P> <P>This study aimed (1) to analyze the association between walking and LBP and (2) to examine this association according to walking duration and overall walking days per week in a general population over 50years of age using a representative sample of Korean adults.</P> <P><B>STUDY DESIGN</B></P> <P>Cross-sectional study.</P> <P><B>PATIENT SAMPLE</B></P> <P>Data from the Korea National Health and Nutrition Examination Surveys V and VI, performed from 2010 to 2015.</P> <P><B>OUTCOME MEASURES</B></P> <P>Multiple logistic regression analysis was performed to determine the association between walking days and duration and LBP. Analysis was restricted to participants aged over 50years who responded to surveys on LBP and walking activity.</P> <P><B>METHODS</B></P> <P>National health and nutrition examination surveys were performed in the Korean general population (N=48,482) from 2010 to 2015. LBP status was surveyed using a self-reported questionnaire form (“Have you complained of LBP for more than 30days during the past 3 months?”). Daily walking activity (low-intensity activity) was evaluated using the following two questions: (1) “During the last 7days, on how many days did you walk for at least 10 minutes at a time? This includes at work and at home, walking to travel from place to place, and any other walking that you have done solely for recreation, sport, exercise, or leisure.” (2) “How much time did you usually spend walking on each of those days?” Walking duration per day was classified into two categories: over 30min/day and over 1h/day. Overall walking days per week were categorized into <3, 3–4, and ≥5days/week. Basic characteristics, comorbidities, socioeconomic status, and other variables were used to create multiple logistic regression models. No sources of funding and no conflicts of interest were associated with this study.</P> <P><B>RESULTS</B></P> <P>Walking for more than 3days per week for over 30 minutes at a time was negatively associated with LBP in the unadjusted (adjusted odds ratio [aOR]: 0.65, p<.001) and fully adjusted logistic regression models (aOR: 0.79, p<.001). Similarly, walking for more than 5days per week for over 1 hour at a time was negatively associated with LBP in the unadjusted (aOR: 0.62, p<.001) and fully adjusted logistic regression models (aOR: 0.76, p<.001). The risk of LBP decreased with increasing walking days and duration.</P> <P><B>CONCLUSIONS</B></P> <P>Our study showed that longer walking duration was associated with a lower risk of LBP using a cross-sectional health survey in the Korean general population. Regular walking with a longer duration for more than 3days/week is significantly associated with a lower risk of LBP in the general population aged over 50years.</P>
Technical Issues on Implementation of GPS Signal Authentication System
So, Hyoungmin,Jang, Jaegyu,Lee, Kihoon,Park, Junpyo The Institute of Positioning 2018 Journal of Positioning, Navigation, and Timing Vol.7 No.3
In recent years, a satellite navigation signal authentication technique has been introduced to determine the spoofing of commercial C/A code using the cross-correlation mode of GPS P(Y) code received at two receivers. This paper discusses the technical considerations in the implementation and application of authentication system simulator hardware to achieve the above technique. The configuration of the simulator consists of authentication system and user receiver. The synchronization of GPS signals received at two devices, data transmission and reception, and codeless correlation of P(Y) code were implemented. The simulation test result verified that spoofing detection using P(Y) codeless correlation could be achieved.
Performance Analysis of Pseudolite Tropospheric Delay Models Using Radiosonde Meteorological Data
So, Hyoungmin,Park, Junpyo,Song, Kiwon The Institute of Positioning 2013 Journal of Positioning, Navigation, and Timing Vol.2 No.1
When pseudolite navigation system is applied to wide area, the tropospheric delay is the main error factor. In this study, we experimentally compared and analyzed the performance of the conventional pseudolite tropospheric delay models. The integration method using radiosonde meteorological data was suggested to derive the reference value for the comparison and analysis. Flight tests were carried out to analyze the performance of the tropospheric delay models according to the elevation angle and distance conditions between the user receiver and the pseudolite. As the results of this study, we provided the basis for the choice of tropospheric delay model appropriate to the relative location characteristics of the pseudolite and the user.