• Title/Summary/Keyword: frequency-response

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Research on flood risk forecast method using weather ensemble prediction system in urban region (앙상블 기상예측 자료를 활용한 도시지역의 홍수위험도 예측 방안에 관한 연구)

  • Choi, Youngje;Yi, Jaeeung
    • Journal of Korea Water Resources Association
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    • v.52 no.10
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    • pp.753-761
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    • 2019
  • Localized heavy storm is one of the major causes of flood damage in urban regions. According to the recent disaster statistics in South Korea, the frequency of urban flood is increasing more frequently, and the scale is also increasing. However, localized heavy storm is difficult to predict, making it difficult for local government officials to deal with floods. This study aims to construct a Flood risk matrix (FRM) using ensemble weather prediction data and to assess its applicability as a means of reducing damage by securing time for such urban flood response. The FRM is a two-dimensional matrix of potential impacts (X-axis) representing flood risk and likelihood (Y-axis) representing the occurrence probability of dangerous weather events. To this end, a regional FRM was constructed using historical flood damage records and probability precipitation data for basic municipality in Busan and Daegu. Applicability of the regional FRMs was assessed by applying the LENS data of the Korea Meteorological Administration on past heavy rain events. As a result, it was analyzed that the flood risk could be predicted up to 3 days ago, and it would be helpful to reduce the damage by securing the flood response time in practice.

Optimization and Evaluation of Flight Control Laws to Satisfy Longitudinal Handling Quality and Stability Margin Requirements (종축 비행성 요구도 및 안정성 여유 만족을 위한 비행제어법칙 최적화 및 평가)

  • Kim, Seong Hyeon;Ko, Deuk Won;Lee, Tae Hyun;Kim, Dong Hwan;Kim, Byoung Soo
    • Journal of Aerospace System Engineering
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    • v.15 no.5
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    • pp.8-15
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    • 2021
  • This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.

Combined Effects of Different Wavelength Laser Stimulations and Electroacupuncture on Neuropathic Pain (파장별 레이저 자극과 전침 결합 시술이 신경병리성 동통에 미치는 영향)

  • Cho, Myoung-rae;Kim, Myeong-hun;Moon, Youngmin;Jeong, Sungho;Na, Chang-su
    • Korean Journal of Acupuncture
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    • v.38 no.3
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    • pp.151-161
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    • 2021
  • Objectives : The effects of a combined stimulation of 658 nm, 830 nm, 904 nm, and 1064 nm laser acupuncture treatment (LAT) and electroacupuncture treatment (EAT) on GB39 and GB34 on neuropathic pain in rats induced by tibial and sural nerve transection were studied in this paper. Methods : To express a neuropathic pain model, surgery was performed to transection rats' tibial and sural nerves. The rats were divided into normal group, control group, and experimental groups. In addition, the experimental groups were divided into 658 nm laser and electroacupuncture (LAT658+EAT), 830 nm laser and electroacupuncture (LAT830+EAT), 904 nm laser and electroacupuncture (LAT904+EAT), and 1064 nm laser and electroacupuncture (LAT830+EAT). For the treatment of the experimental groups, electroacupuncture and different laser wavelengths were alternately applied to GB34 and GB39 twice a week for 3 weeks for 1 minute 30 seconds. The withdrawal response of neuropathic rats' legs by acetone stimulation was observed, as well as the c-Fos in the central gray region in the midbrain of neuropathic rats together with Bax, Bcl2, and mGluR5 expressions associated with apoptosis. Results : Compared with the control group, a significant decrease in the frequency of paw withdrawal in response to acetone allodynia was observed in LAT658+EAT and LAT830+EAT groups in 6th times, LAT904+EAT group in 2nd, 3rd, and 6th times, and LAT1064+EAT group in 2nd and 6th times, respectively. For c-fos positive cells in the central gray region, a significant decrease was observed in LAT830+EAT, LAT904+EAT, and LAT1064+EAT groups in comparison with the control group. In Bax expression, LAT1064+EAT group showed a significant decrease compared to the control group. In Bcl-2 expression, the LAT658+EAT,the LAT904+EAT, and the LAT1064+EAT groups increased significantly compared to the control group. LAT830+EAT, LAT904+EAT, and LAT1064+EAT groups showed significantly increased mGlu5 expression compared to the control group. Conclusions : The combination of laser for each wavelength and electroacupuncture alternately performed in this study is thought to be effective in improving neuropathic pain and apoptosis.

A Pharmacogenomic-based Antidepressant Treatment for Patients with Major Depressive Disorder: Results from an 8-week, Randomized, Single-blinded Clinical Trial

  • Han, Changsu;Wang, Sheng-Min;Bahk, Won-Myong;Lee, Soo-Jung;Patkar, Ashwin A.;Masand, Prakash S.;Mandelli, Laura;Pae, Chi-Un;Serretti, Alessandro
    • Clinical Psychopharmacology and Neuroscience
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    • v.16 no.4
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    • pp.469-480
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    • 2018
  • Objective: Pharmacogenomic-based antidepressant treatment (PGATx) may result in more precise pharmacotherapy of major depressive disorder (MDD) with better drug therapy guidance. Methods: An 8-week, randomized, single-blind clinical trial was conducted to evaluate the effectiveness and tolerability of PGATx in 100 patients with MDD. All recruited patients were randomly allocated either to PGATx (n=52) or treatment as usual (TAU, n=48) groups. The primary endpoint was a change of total score of the Hamilton Depression Rating Scale-17 (HAMD-17) from baseline to end of treatment. Response rate (at least 50% reduction in HAMD-17 score from baseline), remission rate (HAMD-17 score ${\leq}7$ at the end of treatment) as well as the change of total score of Frequency, Intensity, and Burden of Side Effects Ratings (FIBSER) from baseline to end of treatment were also investigated. Results: The mean change of HAMD-17 score was significantly different between two groups favoring PGATx by -4.1 point of difference (p=0.010) at the end of treatment. The mean change in the FIBSER score from baseline was significantly different between two treatment groups favoring PGATx by -2.5 point of difference (p=0.028). The response rate (71.7 % vs. 43.6%, p=0.014) were also significantly higher in PGATx than in TAU at the end of treatment, while the remission rate was numerically higher in PGATx than in TAU groups without statistical difference (45.5% vs. 25.6%, p=0.071). The reason for early drop-out associated with adverse events was also numerically higher in TAU (n=9, 50.0%) than in PGATx (n=4, 30.8%). Conclusion: The present study clearly demonstrate that PGATx may be a better treatment option in the treatment of MDD in terms of effectiveness and tolerability; however, study shortcomings may limit a generalization. Adequately-powered, well-designed, subsequent studies should be mandatory to prove its practicability and clinical utility for routine practice.

Vitalization of Ecological, Scenic, Participative aspects of Urban Agriculture - Focusing on Population Characteristics and Individual Recognitions - (생태, 경관, 참여 측면의 도시농업 활성화 방안 모색 - 인구집단 특성과 개인의 주관적 인식 분석을 중심으로 -)

  • Chang, Insu;Suh, Tongju;Kim, Hong sok(Brian)
    • Journal of the Korean Regional Science Association
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    • v.34 no.4
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    • pp.35-48
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    • 2018
  • The purpose of this study is to empirically investigate the experiences and subjective opinions of urban agriculture in order to explore ways to vitalize urban agriculture. More specifically, we divides environmental value into three categories of ecology, landscape, and participation, and defines a function of urban agriculture to improve environmental values related to the three categories mentioned above. The main results of the empirical analysis using the survey data are summarized as follows. First, the probability of gathering information about urban agriculture is higher in metropolitan cities than small cities, and the larger the residence size, the higher the probability of actual urban agriculture participation. Second, the positive response rate was high for the three categories of urban agriculture, while the negative response rate was high for the surrounding environment. The implications derived from the analysis are as follows. First, the opposite results of experiences of urban agriculture suggests that local governments should further promote urban agriculture-based investment policies. In addition, these policies need to be preceded by analysis of the characteristics of population groups in the region Also, it is necessary to improve the environment through urban agriculture.

Development Strategy of Smart Urban Flood Management System based on High-Resolution Hydrologic Radar (고정밀 수문레이더 기반 스마트 도시홍수 관리시스템 개발방안)

  • YU, Wan-Sik;HWANG, Eui-Ho;CHAE, Hyo-Sok;KIM, Dae-Sun
    • Journal of the Korean Association of Geographic Information Studies
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    • v.21 no.4
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    • pp.191-201
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    • 2018
  • Recently, the frequency of heavy rainfall is increasing due to the effects of climate change, and heavy rainfall in urban areas has an unexpected and local characteristic. Floods caused by localized heavy rains in urban areas occur rapidly and frequently, so that life and property damage is also increasing. It is crucial how fast and precise observations can be made on successful flood management in urban areas. Local heavy rainfall is predominant in low-level storms, and the present large-scale radars are vulnerable to low-level rainfall detection and observations. Therefore, it is necessary to introduce a new urban flood forecasting system to minimize urban flood damage by upgrading the urban flood response system and improving observation and forecasting accuracy by quickly observing and predicting the local storm in urban areas. Currently, the WHAP (Water Hazard Information Platform) Project is promoting the goal of securing new concept water disaster response technology by linking high resolution hydrological information with rainfall prediction and urban flood model. In the WHAP Project, local rainfall detection and prediction, urban flood prediction and operation technology are being developed based on high-resolution small radar for observing the local rainfall. This study is expected to provide more accurate and detailed urban flood warning system by enabling high-resolution observation of urban areas.

Rotordynamic Performance Measurements and Predictions of a FCEV Air Compressor Supported on Gas Foil Bearings (가스 포일 베어링으로 지지되는 연료전지 전기자동차용 공기압축기의 회전체동역학적 성능 측정 및 예측)

  • Hwang, Sung Ho;Moon, Chang Gook;Kim, Tae Ho;Lee, Jongsung;Cho, Kyung Seok;Ha, Kyoung-Ku;Lee, Chang Ha
    • Tribology and Lubricants
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    • v.35 no.1
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    • pp.44-51
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    • 2019
  • The paper presents the rotordynamic performance measurements and model predictions of a fuel cell electric vehicle (FCEV) air compressor supported on gas foil bearings (GFBs). The rotor has an impeller on one end and a thrust runner on the other end. The front (impeller side) and rear (thrust side) gas foil journal bearings (GFJBs) are located between the impeller and thrust runner to support the radial loads, and a pair of gas foil thrust bearings are located on both sides of the thrust runner to support the axial loads. The test GFJBs have a partial arc shim foil installed between the top foil and bump strip layers to enhance hydrodynamic pressure generation. During the rotordynamic performance tests, two sets of orthogonally installed eddy-current displacement sensors measure the rotor radial motions at the rotor impeller and thrust ends. A series of speed-up and coast-down tests to 100k rpm demonstrates the dominant synchronous (1X) rotor responses to imbalance masses without noticeable subsynchronous motions, which indicates a rotordynamically stable rotor-GFB system. Finite element analysis of the rotor determines the rotor free-free (bending) natural modes and frequencies well beyond the maximum rotating frequency. The predicted damped natural frequencies and damping ratios of the rotor-GFB system reveal rotordynamic stability over the speeds of interest. The imbalance response predictions show that the predicted critical speeds and rotor amplitudes strongly agree with the test measurements, thus validating the developed rotordynamic model.

Current Trend in Use of Occupational Therapy Assessment Tool by Pediatric Occupational Therapist (국내 아동 작업치료사의 평가도구 사용 동향)

  • Lee, Sun-Hee;Hong, Cho-Rong;Park, Hae Yean
    • The Journal of Korean Academy of Sensory Integration
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    • v.16 no.3
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    • pp.23-33
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    • 2018
  • Objective : The purpose of this study is to investigate trend in use of occupational therapy assessment tools used by pediatric occupational therapist. Methods : Survey questionnaire developed for this study were used to for data collection. The questionnaires are divided into 10 area: occupational performance, activities of daily living, education, play, sensory-perceptual, motor and praxis, cognition, social interaction skills, development, and physical examination. Total 105 responses were analyzed using descriptive statistics analysis and frequency analysis. Results : For the general process of evaluation in pediatric occupational therapy, major response on the initial evaluation time was 30~60minutes (41.9%), and major response on the re-evaluation period was 3~6months (41.0%). The major assessment tool for each area Canadian Occupation Performance Measure (55.2%) for occupational performance assessments, Wee Functional Independence Measure (57.1%) for activities of daily living assessments, School Function Assessment (2.5%) for education assessments, Knox Preschool Play Scale (28.6%) for play assessments, Developmental Test of Visual Perception (94.3%) for sensory-perceptual assessments, Bruininks-Oseretsky Test of Motor Proficiency (42.9%) for motor and praxis assessments, Evaluation of Social Interaction (6.1%) for social interaction skills assessments, Denver Developmental Screening Test (92.4%) for development assessments, Clinical Observation (89.5%) for physical examination assessments. Conclusion : The study identified the most assessment tools used for specific area by pediatric occupational therapists. The results can be used as a basic data to educate about pediatric occupational therapy evaluation, as well as to develop new assessment tools in pediatric setting in future.

The Effect of Changes in Airbnb Host's Marketing Strategy on Listing Performance in the COVID-19 Pandemic (COVID-19 팬데믹에서 Airbnb 호스트의 마케팅 전략의 변화가 공유성과에 미치는 영향)

  • Kim, So Yeong;Sim, Ji Hwan;Chung, Yeo Jin
    • Journal of Intelligence and Information Systems
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    • v.27 no.3
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    • pp.1-27
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    • 2021
  • The entire tourism industry is being hit hard by the COVID-19 as a global pandemic. Accommodation sharing services such as Airbnb, which have recently expanded due to the spread of the sharing economy, are particularly affected by the pandemic because transactions are made based on trust and communication between consumer and supplier. As the pandemic situation changes individuals' perceptions and behavior of travel, strategies for the recovery of the tourism industry have been discussed. However, since most studies present macro strategies in terms of traditional lodging providers and the government, there is a significant lack of discussion on differentiated pandemic response strategies considering the peculiarity of the sharing economy centered on peer-to-peer transactions. This study discusses the marketing strategy for individual hosts of Airbnb during COVID-19. We empirically analyze the effect of changes in listing descriptions posted by the Airbnb hosts on listing performance after COVID-19 was outbroken. We extract nine aspects described in the listing descriptions using the Attention-Based Aspect Extraction model, which is a deep learning-based aspect extraction method. We model the effect of aspect changes on listing performance after the COVID-19 by observing the frequency of each aspect appeared in the text. In addition, we compare those effects across the types of Airbnb listing. Through this, this study presents an idea for a pandemic crisis response strategy that individual service providers of accommodation sharing services can take depending on the listing type.

A Comparative Study on the Brand Experiences of Metaverse and Offline Stores (메타버스와 오프라인 스토어의 브랜드 체험 비교 연구)

  • Gwang-Ho Yi;Yu-Jin Kim
    • Science of Emotion and Sensibility
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    • v.26 no.2
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    • pp.53-66
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    • 2023
  • In recent times, more fashion brands have been seeking ways to use metaverse platforms, in which users can actively participate, as their new brand touch-points. This study aims to compare the brand experiences of the fashion brand Gentle Monster's offline store and its equivalent metaverse store. By changing the order of offline and metaverse visits, two groups participated in the field study that allowed them to experience directly the offline and metaverse stores. As a result of the analysis, the following findings were discovered: (1) In the overall experiential response, the frequency of sensory modules responding to new information was much higher than that of feeling experiences; (2) Experiential responses were more active in the offline store where the subjects could touch and use products directly rather than in the metaverse; (3) Among the four types of theme space, the experiential response was the most frequent in the product space; (4) The first group that visited the metaverse store before the offline store showed a more active experience than the second group that visited the offline store first. Finally, the results of this study show that metaverse brand stores in virtual space not only provide differentiated experiences beyond the spatiotemporal constraints of real space but can also be used as a strategic tool to make offline store experiences more meaningful and rich.