• Title/Summary/Keyword: scale-model

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Impedance-based Long-term Structural Health Monitoring for Jacket-type Tidal Current Power Plant Structure in Temperature and Load Changes (온도 및 하중 영향을 고려한 임피던스 기반 조류발전용 재킷 구조물의 장기 건전성 모니터링)

  • Min, Jiyoung;Kim, Yucheong;Yun, Chung-Bang;Yi, Jin-Hak
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.5A
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    • pp.351-360
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    • 2011
  • Jacket-type offshore structures are always exposed to severe environmental conditions such as salt, high speed of current, wave, and wind compared with other onshore structures. In spite of the importance of maintaining the structural integrity for offshore structure, there are few cases to apply structural health monitoring (SHM) system in practice. The impedance-based SHM is a kind of local SHM techniques and to date, numerous techniques and algorithms have been proposed for local SHM of real-scale structures. However, it still requires a significant challenge for practical applications to compensate unknown environmental effects and to extract only damage features from impedance signals. In this study, the impedance-based SHM was carried out on a 1/20-scaled model of an Uldolmok current power plant structure under changes in temperature and transverse loadings. Principal component analysis (PCA) was applied using conventional damage index to eliminate principal components sensitive to environmental change. It was found that the proposed PCA-base approach is an effective tool for long-term SHM under significant environmental changes.

A Study on the Dynamic Purchase Response Function for Fashion Goods (패션제품의 동태적 구매반응함수에 관한 연구)

  • Lee, Min Ho;Kwak, Young Sik;Hwang, Sun-Jin
    • Journal of the Korean Society of Costume
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    • v.64 no.2
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    • pp.35-49
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    • 2014
  • In cases of fashion businesses operating by consignment, base estimate on quantity of sales is the most essential part of merchandising. This study classified factors influential to sales into factors with systematic influence and factors with unsystematic influence. In order to find out influence of each factor on sales, non-linear regression was used with SPSS package on the basis of actual data on sales for 5 years for sport shoes brand. Major findings of this study are as follows. First, price level had significant negative(-) influence on sales. Second, price expectation effects had significant negative(-) influence on sales. Third, competitor's price effect showed significant negative(-) value. Fourth, day-of-the-week effect showed significant positive(+) effect. The theoretical marketing implications of this study are as follows. First, study on price leads to expansion of the researches from apparels to sport shoes. Field of study on price was enlarged through expansion of variable of study from price level and price expectation effect to promotion, day-of-the-week effect and rainfall effect. Second, quantitative scale of day-of-the-week effect was found and it could be confirmed that there was seasonal differences with day-of-the-week effect. Implications of above findings on marketing managers are as follows. First, it was found that an increase in competitiveness of brand power and a decline in absolute value of competitor's price effect can be realized when new product groups are developed to meet the unsatisfied needs in the market. Second, it was possible to find out the parameters scales of the price response function, making it possible to estimate sales for the next season, and in turn realize increase in rate of sales and profit rate. This research is based on the dynamic price response function, which is rare to find in the apparel business and it academic significance due to its expanding response model which was focused on price in conventional researches to non-systematic variables.

5-MHz Volume Backscattering Strength Measurements from Suspended Sediment Concentrations (5 MHz 신호를 이용한 부유물의 농도에 따른 후방산란강도 측정)

  • Lee, Changil;Choi, Jee Woong
    • The Journal of the Acoustical Society of Korea
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    • v.32 no.1
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    • pp.14-21
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    • 2013
  • The erosion, suspension, and transport of sediment frequently occur in the coastal waters and estuarine. These processes often generate the so-called fluid mud layer, which is defined as a high-concentration aqueous suspension of fine grained sediment (> 10 g/l), consisting mainly of silt and clay-size particles. Therefore the high-resolution ultrasound is mostly used to detect or monitor the fluid mud layer. Because the sound attenuation tends to increase rapidly with the suspended sediment concentration, it is necessary to consider the accurate attenuation correction to estimate the backscattering strengths from the suspended sediment layers. In this paper, the volume backscattering strengths with various suspended sediment concentrations were measured using 5-MHz ultrasound signal in a small-scale water tank. The sound attenuation due to the viscosity and scattering from suspended sediment particles was predicted by the Richard's model and applied to the sonar equation to estimate the volume backscattering strengths from the suspended sediment concentrations. For the case that the additional attenuation was not considered, the volume backscattering strengths increased to the concentration of 20 g/l, and over this point, the backscattering strengths were roughly constant. However, for the case that the attenuation due to the suspended sediment concentration was considered, the backscattering strengths increased with the concentration.

Experimental Investigations on Air Entrainment Through an Air Vent Installed on a Gated Conduit of a Reservoir (저수지 취수시설의 공기관을 통한 공기연행에 대한 실험적 연구)

  • Kang, Min Goo;Park, Young Jin;Kim, Ji Seong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.33 no.1
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    • pp.149-155
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    • 2013
  • In this study, factors that affect the air entrainment within a closed conduit by air drawn in through an air vent are investigated using a hydraulic scale model, which represents a gated circular conduit system connected to the intake tower of an irrigation reservoir. In addition, using data obtained during the hydraulic experiments, experimental equations are developed to estimate the amount of air drawn in through the air vent. In case of pressurized flow conditions downstream of hydraulic jumps, the relationships between $\frac{Q_a}{Q_w}$ and $Fr_g-1$ of the data form a experimental equation, $\frac{Q_a}{Q_w}=0.0304(Fr_g-1)^{1.0622}$; in case of free surface flow conditions, $\frac{Q_a}{Q_w}=0.0271(Fr_g-1)^{1.8205}$. Comparing two data sets observed under the two flow regimes with the results of previous researchers, patterns of the data sets are similar to the results estimated using the equations presented previously, and this indicates that the quality of the data obtained during the hydraulic experiments is ensured. In addition, it is revealed that air entrainment phenomena in the regions close to air vents are affected by the characteristics of supercritical flows downstream of gates. Finally, it is concluded that the equation developed for pressurized flow conditions can be applied to design of air vents.

Spatial Analysis of Typhoon Genesis Distribution based on IPCC AR5 RCP 8.5 Scenario (IPCC AR5 RCP 8.5 시나리오 기반 태풍발생 공간분석)

  • Lee, Sungsu;Kim, Ga Young
    • Spatial Information Research
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    • v.22 no.4
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    • pp.49-58
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    • 2014
  • Natural disasters of large scale such as typhoon, heat waves and snow storm have recently been increased because of climate change according to global warming which is most likely caused by greenhouse gas in the atmosphere. Increase of greenhouse gases concentration has caused the augmentation of earth's surface temperature, which raised the frequency of incidences of extreme weather in northern hemisphere. In this paper, we present spatial analysis of future typhoon genesis based on IPCC AR5 RCP 8.5 scenario, which applied latest carbon dioxide concentration trend. For this analysis, we firstly calculated GPI using RCP 8.5 monthly data during 1982~2100. By spatially comparing the monthly averaged GPIs and typhoon genesis locations of 1982~2010, a probability density distribution(PDF) of the typhoon genesis was estimated. Then, we defined 0.05GPI, 0.1GPI and 0.15GPI based on the GPI ranges which are corresponding to probability densities of 0.05, 0.1 and 0.15, respectively. Based on the PDF-related GPIs, spatial distributions of probability on the typhoon genesis were estimated for the periods of 1982~2010, 2011~2040, 2041~2070 and 2071~2100. Also, we analyzed area density using historical genesis points and spatial distributions. As the results, Philippines' east area corresponding to region of latitude $10^{\circ}{\sim}20^{\circ}$ shows high typhoon genesis probability in future. Using this result, we expect to estimate the potential region of typhoon genesis in the future and to develop the genesis model.

Profiling Approach for the Choice between Speculation and Postponement Strategy in Supply Chain Management (공급사슬관리의 예측전략과 지연전략 선택을 위한 프로파일링 접근법)

  • Kang, Sung-Wook;Kim, Gyu-Bae
    • Journal of Distribution Science
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    • v.12 no.4
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    • pp.47-54
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    • 2014
  • Purpose - The postponement strategy, which delays the form, place, and production of products as late as possible, has been widely considered as a competitive supply chain management scheme in an era of mass customization and modular manufacturing. An interesting business phenomenon is that not all manufacturing/logistics firms choose the postponement strategy. Given that postponement is a counter-measure to speculation, which has some advantages under certain environments, the current imprudent inclination toward the postponement strategy may cause firms to lose the potential of the speculation strategy, an alternative strategy in supply chain management. Building on the logistics and manufacturing literature, this study examines characteristics of two contrasting strategies, postponement and speculation, and major factors favoring each strategy. Research design, data, and methodology - We apply the profiling approach to two business cases, HP printer and LG mobile phone. The profiling approach is a method of choosing a particular strategy aligned with environmental factors. While various approaches have been used to check the fit between a business strategy and environmental factors, the literature on manufacturing strategy and logistics has commonly adopted the profiling approach. Major factors used in profiling variables are derived from the literature. Two samples, HP printer and LG mobile phone, are selected, because they represent major characteristics appropriate for each strategy. The profiling is based on data from semi-organized interviews with managers. Results - The profiling approach shows that the postponement strategy is a suitable one for HP printers. Most factors, such as product life cycle, large production volume, low-price, product value, and monetary density, support delaying end products until as late as possible. Despite some exceptions, such as delivery time and economy of scale, our analysis states that the overall profile of HP printer is favorable for the postponement strategy. On the other hand, LG mobile phone may adapt the speculation strategy. Although it has large production volume and low delivery frequency, most characteristics support the speculation strategy for this product. An interesting finding is that, despite common perception that advanced technology products such as mobile telephones favor the postponement strategy, profiling proposes the speculation strategy for this product. Conclusions - Our analysis shows that speculation is not the universal option for supply chain management, and that, when choosing a specific strategy, one should consider many factors simultaneously. A major implication of our work is to emphasize the role of environmental factors such as supply chain variables in choosing an inventory strategy, and the importance of fit rather than solely strategic orientation. A theoretical contribution is to demonstrate the benefit of the simultaneous consideration of business variables in choosing specific strategies. For practitioners, our work leads us to consider the existence and the potential of speculation as a counter-measure to postponement. In addition, the comprehensive framework in this research may be instantly used in examining a practical strategy.

Analysis on the Effects of Land Cover Types and Topographic Features on Heat Wave Days (토지피복유형과 지형특성이 폭염일수에 미치는 영향 분석)

  • PARK, Kyung-Hun;SONG, Bong-Geun;PARK, Jae-Eun
    • Journal of the Korean Association of Geographic Information Studies
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    • v.19 no.4
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    • pp.76-91
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    • 2016
  • The purpose of this study is to analyze the effects of spatial characteristics, such as land cover and topography, on heat wave days from the city of Milyang, which has recently drawn attention for its heat wave problems. The number of heat wave days was calculated utilizing RCP-based South Korea climate data from 2000 to 2010. Land cover types were reclassified into urban area, agricultural area, forest area, water, and grassland using 2000, 2005, and 2010 land cover data constructed by the Ministry of Environment. Topographical features were analyzed by topographic position index (TPI) using a digital elevation model (DEM) with 30 m spatial resolution. The results show that the number of heat wave days was 31.4 days in 2000, which was the highest, followed by 26.9 days in 2008, 24.2 days in 2001, and 24.0 days in 2010. The heat wave distribution was relatively higher in agricultural areas, valleys, and rural areas. The topography of Milyang contains more mountainous slope (51.6%) than flat (19.7%), while large-scale valleys (12.2%) are distributed across some of the western region. Correlation analysis between heat wave and spatial characteristics showed that the correlation between forest area land cover and number of heat wave days was negative (-0.109), indicating that heat wave can be mitigated. Topographically, flat areas and heat wave showed a positive correlation (0.305). These results provide important insights for urban planning and environmental management for understanding the impact of land development and topographic change on heat wave.

Estimation of Representative Area-Level Concentrations of Particulate Matter(PM10) in Seoul, Korea (미세먼지(PM10)의 지역적 대푯값 산정 방법에 관한 연구 - 서울특별시를 대상으로)

  • SONG, In-Sang;KIM, Sun-Young
    • Journal of the Korean Association of Geographic Information Studies
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    • v.19 no.4
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    • pp.118-129
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    • 2016
  • Many epidemiological studies, relying on administrative air pollution monitoring data, have reported the association between particulate matter ($PM_{10}$) air pollution and human health. These monitoring data were collected at a limited number of fixed sites, whereas government-generated health data are aggregated at the area level. To link these two data types for assessing health effects, it is necessary to estimate area-level concentrations of $PM_{10}$. In this study, we estimated district (Gu)-level $PM_{10}$ concentrations using a previously developed pointwise exposure prediction model for $PM_{10}$ and three types of point locations in Seoul, Korea. These points included 16,230 centroids of the largest census output residential areas, 422 community service centers, and 610 centroids on the 1km grid. After creating three types of points, we predicted $PM_{10}$ annual average concentrations at all locations and calculated Gu averages of predicted $PM_{10}$ concentrations as representative Gu-estimates. Then, we compared estimates to each other and to measurements. Prediction-based Gu-level estimates showed higher correlations with measurement-based estimates as prediction locations became more population representative ($R^2=0.06-0.59$). Among the three estimates, grid-based estimates gave lowest correlations compared to the other two(0.35-0.47). This study provides an approach for estimating area-level air pollution concentrations and assesses air pollution health effects using national-scale administrative health data.

Dynamic Response of Plate Structure Subject to the Characteristics of Explosion Load Profiles - Part A: Analysis for the Explosion Load Characteristics and the Effect of Explosion Loading Rate on Structural Response - (폭발하중 이력 특성에 따른 판 구조물의 동적응답 평가 - Part A: 폭발하중 특징 및 재하속도의 영향 분석 -)

  • Kang, Ki-Yeob;Choi, Kwang-Ho;Ryu, YongHee;Choi, JaeWoong;Lee, Jae-Myung
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.28 no.2
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    • pp.187-195
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    • 2015
  • The gas explosions in offshore installations are known to be very severe according to its geometry and environmental conditions such as leak locations and wind directions, and a dynamic response of structures due to blast loads depends on the load profile. Therefore, a parametric study has to be conducted to investigate the effects of the dynamic response of structural members subjected to various types of load shapes. To do so, a series of CFD analyses was performed using a full-scale FPSO topside model including detail parts of pipes and equipments, and the time history data of the blast loads at monitor points and panels were obtained by the analyses. In this paper, we focus on a structural dynamic response subjected to blast loads changing the magnitude of positive/negative phase pressure and time duration. From the results of linear/nonlinear transient analyses using single degree of freedom(SDOF) and multi-degree-of freedom(MDOF) systems, it was observed that dynamic responses of structures were significantly influenced by the magnitude of positive and negative phase pressures and negative time duration.

The Effects of Parental Training Interventions on ADHD in Children: A Meta-Analysis (ADHD 아동을 위한 부모훈련 중재의 효과 연구: 메타분석)

  • Ra, Dae Yeop;Park, Hae Yean
    • The Journal of Korean Academy of Sensory Integration
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    • v.18 no.1
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    • pp.56-72
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    • 2020
  • Objective : The purpose is to analyze the effects of parent training interventions in reducing the symptoms of Attention Deficit Hyperactivity Disorder (ADHD) and to provide a basis for the effects. Methods : We collected literature published in international academic journals from 2009 to 2019 through ProQuest and Scopus databases. The search key terms were (ADHD OR Attention Deficit Hyperactivity Disorder) AND (Parent OR Mother OR Father) AND (Training OR Program OR Therapy OR Intervention) AND (Randomized OR Randomised OR Randomly). The PEDro scale was used to evaluate the quality of the studies, and a meta-analysis was conducted through Comprehensive Meta-Analysis 3.0. Results : Of 628 studies that we reviewed, 20 were eligible for inclusion. of parental training interventions for children with ADHD appeared close to a medium effect size while parent-child interventions (0.639) appeared to have a medium to large effect size. Oppositional defiant behavior and conduct disorder (0.737) in children and children's emotions (0.679) appeared close to a large effect size. ADHD symptoms hyperactivity and impulsivity (0.590) and child behavior (0.521) appeared to be over a medium effect size. We chose a random-effects model since heterogeneity tests showed significant results. Conclusion : We were able to confirm the effects of parent training interventions on the symptoms of children with ADHD. This will be used as evidence to provide a clinical basis for occupational therapists. More research related to parental training interventions should be carried out to ensure better reporting in the future.