Optical fiber AC voltage sensor

Kim, Soobong,Park, Jaehee,Han, Won-Taek Wiley Subscription Services, Inc., A Wiley Company 2009 MICROWAVE AND OPTICAL TECHNOLOGY LETTERS Vol.51 No.7

<P>A fiber-optic interferometric voltage sensor with a high-sensitivity is investigated. The fiber-optic voltage sensor is composed of an in-line Michelson interferometer bonded to a piezoelectric transducer (PZT). The in-line Michelson interferometer is a hollow optical fiber spliced to a single-mode fiber at one end and cleaved at the other end. A phase shift in the sensor output signal is induced when applying an AC voltage to the PZT; and a higher-amplitude voltage produces an output interference signal with a higher frequency. The relation between the amplitude of the applied voltage and the phase shift of the sensor output signal is found to be approximately linear and the slope of the relation graph is about 0.116 πradian/V. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1689–1691, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24434</P>

Microscopic Optical Beam Profile Measurement Technique for Near-Infrared Light by Using a Scanning Thermal Probe

Kim Hyuntae,Choi Soobong,Park Woongkyu,Cho Sangjoon,Kim Cheolsu 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.10

In this paper, we report that the beam profile of the near-infrared light from superluminescent diodes (SLDs) can be measured with a resolution below the diffraction limit by using the photothermal effect and scanning thermal microscopy (SThM). Due to the sub-diffraction resolution of SThM, the beam profile measured using SThM was much clearer than the beam profile obtained by using the knife-edge method. By stacking cross-sectional images of the optical beam profile obtained by using SThM, we were able to obtain successively the three-dimensional optical beam profile. Our novel method of using small probes to measure optical beam profiles is compatible with conventional microscopy systems and can potentially be used in various applications.

Bridge Health Monitoring with Consideration of Environmental Effects

Kim, Yuhee,Kim, Hyunsoo,Shin, Soobong,Park, Jong-Chil The Korean Society for Nondestructive Testing 2012 한국비파괴검사학회지 Vol.32 No.6

Reliable response measurements are extremely important for proper bridge health monitoring but incomplete and unreliable data may be acquired due to sensor problems and environmental effects. In the case of a sensor malfunction, parts of the measured data can be missing so that the structural health condition cannot be monitored reliably. This means that the dynamic characteristics of natural frequencies can change as if the structure is damaged due to environmental effects, such as temperature variations. To overcome these problems, this paper proposes a systematic procedure of data analysis to recover missing data and eliminate the environmental effects from the measured data. It also proposes a health index calculated statistically using revised data to evaluate the health condition of a bridge. The proposed method was examined using numerically simulated data with a truss structure and then applied to a set of field data measured from a cable-stayed bridge.

An Analysis of Internal Structural Organisation of UK's Urban Fringe Management Initiatives and Its Roles

Kim, Yong-Bum,Kim, Soobong,Cho, Jin-Hee 한국환경과학회 2004 한국환경과학회지 Vol.13 No.5

The purpose of this research was to investigate and analyse the internal structural organisation of UK's urban fringe management initiatives and its roles. Caerphilly Mountain Countryside Service and Thames Chase Community Forest Initiatives were investigated. The Caerphilly Mountain Countryside Service Initiative operates through a tiered structure consisting of the Caerphilly Mountain Joint Committee, the Officers' Working Party. and the management team. The Thames Chase Community Forest Initiative is operated through a tiered structure comprising the Thames Chase Joint Committee and the management team. Although the role of each management initiative is invested differently in certain internal organisational bodies, such as the governance body and the management body, what is common to all the urban fringe management initiatives is that the governance body within each management initiative tries to speak with one voice to bring about an effective operation process, and the management team employs a variety of devices to secure the enrolment of a variety of interest groups in its operational processes.

대학생의 건강증진 - 계명대학교 성서캠퍼스의 보행성을 중심으로

Soobong Kim,Eunjeong Jeon,Hyeshick Moon 전북대학교 부설 휴양및경관계획연구소 2015 휴양및경관연구 (J East Asian Landscape Studies) Vol.9 No.2

본 연구는 캠퍼스 내 대학생들의 건강증진 가능성을 알아보기 위해 대학생의 건강상태, 신체활동 수준, 그리고 워커빌 리티에 영향을 주는 캠퍼스 공간에 대한 만족도를 확인해보고자 하였으며, 그 결과는 다음과 같다. 첫째, 대학생들의 건강상태 요인으로서 건강관련 삶의 질 측정결과 5개 영역 모두 건강한 상태였으나, 불안/우울 영역 에서 상대적으로 낮은 수준이었다. 또한, 조사대상자의 과반수가 저체중 또는 과체중・비만으로 건강증진의 필요성이 있음을 보여주었다. 둘째, 학생들은 신체활동 중 걷기/산책을 가장 선호한다고 응답하여 캠퍼스 워커빌리티 향상의 필요성을 제시하는 결과라 볼 수 있지만, 대학생들의 실제 캠퍼스 내 걷기수준은 단지 33.6% 만이 규칙적인 운동을 하고 있으며 대부분의 학생들은 앞으로 규칙적인 신체활동을 할 의사가 있다고 응답하였다. 특히 여학생의 경우 단지 18%(남학생, 48.4%)만이 규칙적으로 운동을 실천하므로 앞으로 여학생의 신체활동을 증가시키기 위한 환경을 조성할 필요성이 있겠다. 이와 더불어 신체활동의 건강증진 효과를 기대하기 위해서는 신체활동 시간도 중요하기 때문에 체육시설뿐만 아니라 캠퍼스의 보도, 산책로 등의 환경개선을 통해 1시간 이상 걷는 학생들의 비율을 증대할 필요성이 있다고 사료된다. 마지막으로, 계명대학교 학생들의 캠퍼스 공간에 대한 만족도를 조사한 결과 100점 만점으로 환산했을 때 54.8점에서 68.0점 수준으로 조사되었다. 걷기와 관련한 심리적 측면과 산책로에 대해서는 만족하고 있었으나, 걷기와 관련한 심미적 측면과 교통사고 안전 및 범죄 안전성 그리고 여성 혼자 걷기나 야간에 걷기의 안정성에 대해서는 다소 만족하지 않는 것을 알 수 있었다. 캠퍼스의 골격을 이루는 차량중심의 도로체계는 보행성을 저해하는 가장 큰 요소라 판단되며, 장기적 관점에서 보행자가 우선이 되는 캠퍼스 환경 개선이 요구된다 하겠다. The present study aimed to investigate potential of promoting health among university students for whom health conditions, physical activity, and walking-related campus satisfaction were identified. The results are as follows. First, when health-related life quality was measured in terms of five categories (exercise capacity, self-management, daily life, pain/discomfort, and anxiety/depression), the majority of students were healthy and showed a relatively lower score in the anxiety/depression category. Half of the participants could benefit from health promotion due to being underweight, overweight, or obese. Second, the students mostly responded walking as their favorite physical activity. Although this result may suggest the need for improved campus walkability, only 33.6% of university students regularly participated in walking exercises on campus, whereas most students responded that they intended to do so regularly in the future. In particular, since only 18% of female students exercised regularly (versus male students, 48.4%), it seems necessary to foster an environment that increases the physical activities of female students. At the same time, since an important effect of health promotion involves increased physical activity, it is necessary to implement environmental improvements that increase the ratio of students who walk more than 1 h including on-campus sidewalks, trails, and sports facilities. Finally, a survey of Keimyung University students of their satisfaction with on-campus spaces resulted in 54.8-68.0 of 100 possible points. The students were satisfied with the psychological aspects and trails but relatively less satisfied with walking-related aesthetic aspects, safety related to traffic accidents and crime, and safety of women who were walking alone or at night. The car-centric street system that is the main frame of campus is considered the largest inhibitor of walkability, so a long-term pedestrian-centric focus is required to improve the walking-related campus environment and promote health.

A Study on Daegu City Citizen’s Consciousness about Urban Green Space for Heat Wave Mitigation

Soobong Kim,Yoojung Lee,Hyeshick Moon 전북대학교 휴양및경관계획연구소 2018 휴양및경관연구 (J East Asian Landscape Studies) Vol.12 No.1

Daegu City has the most number of heat waves every year in the last 10 years among 7 metropolitan cities in Korea. As the slang, such as ‘Daefrica(Daegu + Africa)’ shown, Daegu City is recognized as a high temperature region in the summer. The purpose of this study is to understand the perception of urban green space as a mediator for heat wave mitigation for Daegu citizens. First, about 93.3% of the respondents perceived what the heat was. The most frequent cause of the increase in the number of heat waves was the increase in energy use (34.9%), ‘indiscriminate development’ (24.9%), ‘automobile and traffic increase’ (17.9%), ‘greenery reduction’ (12.6% ) were the most common cause. Second, 87.1% of respondents had positive perception about the mitigation effect on the effect of urban green space as a medium to mitigate the heat. In addition, 26.7% of respondents answered that they are very effective in mitigating the effect of the heat of urban greenery, and 95.1% of them responded more than ‘normal’. Third, as a result of examining the priorities of short and long-term heat-related policies, the short term was the highest (37.5%) in responding to ‘electricity tariff realization’ because of the high dependence on air conditioners. In contrast to the short-term perspective, the long-term policy for mitigating the heat wave was overwhelmingly supported by ‘expansion of urban green areas’ (50.7%). This is a result of confirming Daegu citizens’ consciousness which is highly evaluating the effect of urban green space as a medium for mitigating the heat. Fourth, the importance and performance of ‘urban green space type’ for mitigation of the heat wave were examined. The type of urban green space belonging to the phenomena maintenance area (quadrant Ⅰ), which both had high importance and performance, was classified as ‘neighborhood park’. In addition, it was surveyed as ‘Ssamji(mini) Park’ as the type of urban greenery in the concentrated improvement area (quadrant Ⅱ) where the importance is high but the performance is low. We believe that the value of urban green areas for mitigating the heat waves has been fully recognized through the recognition of Daegu citizens. We hope that the results of this study will be used as basic data for future Daegu city heat and urban greening policy.

Factors Influencing the Spatial Variation of Microplastics on High-Tidal Coastal Beaches in Korea.

Kim, In-Sung,Chae, Doo-Hyeon,Kim, Seung-Kyu,Choi, SooBong,Woo, Seung-Bum Springer-Verlag 2015 Archives of environmental contamination and toxico Vol.69 No.3

<P>The presence and distribution characteristics of microplastics become a big issue due to the adverse effects on marine organisms caused by not only microplastics but any incorporated and/or adsorbed pollutants. Distribution of microplastics (50- to 5000-μm size) was determined for three sandy beaches on an isolated island in a high-tidal costal region to elucidate spatial distributions in relation to beach locations. The abundances of microplastics (n?=?21) measured were 56-285,673 (46,334??71,291) particles/m(2) corresponding to the highest level globally. Out of observed polymer types, expanded polystyrene was overwhelmingly dominant. Although lying toward the estuary of the largest river in the country, the north-side beach contained a 100-fold lower abundance than two south-side beaches that faced southerly wind and currents that were prevalent throughout the study season. In addition, distinct differences between the beaches on either side were also present in terms of size distribution and spatial homogeneity of microplastics on the same beach. Winds and currents are therefore considered to be the driving forces in the distribution of microplastics.</P>

Study on Park Maintenance Status and Improvement Plan Using IPA Analysis - Focused on Neighborhood Parks in Daegu-si -

Soobong Kim,Dongkweon Lee,Hyeshick Moon 전북대학교 휴양및경관계획연구소 2017 휴양및경관연구 (J East Asian Landscape Studies) Vol.11 No.3

Despite the importance of city parks and the changes in perception and involvement of users, park management budgets are constantly being contracted. Accordingly, the problems on maintenance control of neighborhood parks are now being realized, and studies on management improvement are required. This study is focused on the operation conditions and user satisfaction of the neighborhood parks in Daegu. Based on the analysis, efficient park management measures are suggested and baseline data are provided for subsequent studies. Targeting the neighborhood parks that the primary local government of Daegu is directly managing, the maintenance management costs were compared for a period of five years, and the average budget per unit area was calculated based on the completed neighborhood parks. Eight neighborhood parks were selected, including Dalseo-gu, whose average budget per unit area is the highest, and Buk-gu, where it is the lowest. Further, field and user attitude surveys were carried out. From the results of the field survey, the administrative status on neighborhood parks of Dalseo-gu and Buk-gu showed a satisfactory level, beyond the average one. The management score on neighborhood parks of Dalseo-gu appeared higher than that in Buk-gu. According to the results of the attitude survey, which targeted the users of these parks, the main users utilizing the neighborhood parks were nearby residents, and their share of responses indicating that they go to the park on foot was the highest, 74.6%. Regarding the importance and satisfaction on the elements that compose the parks, classified in 7 point-scaled criteria, the favorable answers were those over 5 points. According to the levels of user satisfaction calculated based on this method, Buk-gu ranked higher than Dalseo-gu. Based on the expected level of service and the evaluation of how they are perceived, through an IPA analysis, the park facilities were divided into to four areas. As a result, it emerged that continuous interest and intensive management of the properties would be required.

GIS를 활용한 쓰레기 매립장 적지분석에 관한 연구

김수봉(Soobong Kim),최소정(So-Jeong Choe) 계명대학교 낙동강환경원 1998 環境科學論集 Vol.3 No.1

Strengthened and flexible pile-to-pilecap connections for integral abutment bridges

WooSeok Kim,Jaeha Lee,Kyeongjin Kim,Soobong Park,정유석 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.4

Pile-to-pilecap connection performance is important as Integral abutment bridges (IABs) have no expansion joints and their flexible weak-axis oriented supporting piles take the role of the expansion joint. This connection may govern the bridge strength and the performance against various lateral loads. The intention of this study is to identify crack propagation patterns when the pile-to-pilecap connection is subjected to lateral loadings and to propose novel connections for improved performance under lateral loadings. In this study, eight different types of connections were developed and modeled, using Abaqus 6.12 to evaluate performances. Three types were developed by strengthening the connections using rebar or steel tube: (i) PennDOT specification; (ii) Spiral rebar; and (iii) HSS tube. Other types were developed by softening the connections using shape modifications: (i) cylindrical hole; (ii) reduced flange; (iii) removed flange; (iv) extended hole; and (v) slot hole connection types. The connections using the PennDOT specification, HSS tube, and cylindrical hole were shown to be ineffective in the prevention of cracks, resulting in lower structural capacities under the lateral load compared to other types. The other developed connections successfully delayed or arrested the concrete crack initiations and propagations. Among the successful connection types, the spiral rebar connection allowed a relatively larger reaction force, which can damage the superstructure of the IABs. Other softened connections performed better in terms of minimized reaction forces and crack prevention.