• Journal of Power Electronics
• /
• 제18권2호
• /
• pp.445-455
• /
• 2018

A novel algorithm is proposed to regulate the neutral point potential in neutral point clamped three-level inverters. Oscillations of the neutral point potential and an unbalanced dc-link voltage cause distortions of the output voltage. Large capacitors, which make the application costly and bulky, are needed to eliminate oscillations. Thus, the algorithm proposed in this paper utilizes the finite-control-set model predictive control and the multistage medium vector to solve these issues. The proposed strategy consists of a two-step prediction and a cost function to evaluate the selected multistage medium vector. Unlike the virtual vector method, the multistage medium vector is a mixture of the virtual vector and the original vector. In addition, its amplitude is variable. The neutral point current generated by it can be used to adjust the neutral point potential. When compared with the virtual vector method, the multistage medium vector contributes to decreasing the regulation time when the modulation index is high. The vectors are rearranged to cope with the variable switching frequency of the model predictive control. Simulation and experimental results verify the validity of the proposed strategy.

• 유통과학연구
• /
• 제20권2호
• /
• pp.55-64
• /
• 2022

Purpose: This research is aimed to study the level of the intellectual potential distribution, as well as the correlation between economic growth and key indicators of intellectual potential in each region of Kazakhstan. A review of the conceptual framework shows that there is a large body of research evaluating the level of intellectual potential in different ways based on different factors. Research design, data, and methodology: The research methodology is divided into two groups the integral index method using the normalization of indicators, weighting, and ranking; the method of correlation analysis. By the proposed methodological approaches, were calculated a set of factors affect the distribution of the intellectual potential. Statistics are taken for indicators of development of the intellectual potential for 2011-2020 from the Bureau of National Statistics. Results: Ranking results showed gaps between regions in Kazakhstan by the level of intellectual potential. Correlation analysis results revealed a statistically significant relationship on expenditures on R&D, computer literacy, innovative products, number of PhD students, and cultural and leisure indicators. Conclusions: Based on the obtained results of the intellectual potential level development there were given recommendations for the reproduction and regulation of the intellectual potential in the future.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.511-514
• /
• 2007

This study aims to derive the effect of road traffic noise perception by the visual and aural information through a laboratory experiment. To verify the result more precisely, ME(Magnitude Estimation) and SD(Semantic Differential Method) evaluation on the effect of visual and aural effect were carried out by 43 university students. As the result, up to 10% of psychological reduction effect was shown under the 65dB(A). As the noise level, it was analyzed that the vision affected about 7dB(A) and sound affected 5dB(A). However, if these two are given simultaneously, mainly sound affects to reduce the annoyance of noise and the vision next. Compared with the urban central circumstances, this effect(2dB(A) under 65dB(A) noise) was shown smaller than field test.

• International Journal of Advanced Culture Technology
• /
• 제9권3호
• /
• pp.23-33
• /
• 2021

"China's Western Development Policy" has brought multiple opportunities to the development of tourism in Southwest China including Sichuan, Guizhou, Yunnan, Chongqing and Tibet. The 4 provinces and 1 municipality overall show a certain degree of accumulation effect and coordinated development in tourism due to their location, traffic and traditional economic cooperation. This study takes the Southwest China as the research object and utilized the spatial dislocation model and the tourism spatial misalignment index to estimate the mismatch degree between tourism resources and tourism income among provinces and try to find out the internal reason background. The results show that each of the five provinces has its own advantages in index of economy, tourism resources, human resource, and transportation, leading to differences in the center of gravity of the entire region in all aspects. In view of the results of spatial dislocation analysis, suggestions for improvement and optimization are put forward to promote the high-quality development of tourism in Southwest region. development.

• Journal of Community Nutrition
• /
• 제6권2호
• /
• pp.97-102
• /
• 2004

A cross-sectional epidemiologic study was conducted to evaluate vitamin C nutritional status by assessing dietary intake and blood vitamin C level and to identify the relationships between dietary vitamin C intake, serum vitamin C level and blood lead level in Korean lead workers. The study population was 118 lead workers from two battery manufacturing factories and 63 non-lead-exposed controls. A food consumption survey was conducted by the 24-hr recall method to determine the dietary vitamin C intake level. The anthropometric measurements, blood collection, and survey were performed between September and November, 2000. Blood lead levels and serum vitamin C levels were measured using an atomic absorption spectrometer and high performance liquid chromatography, respectively. Vitamin C nutritional status of Korean lead workers was lower than that of the control group, in terms of both dietary intake and the biochemical index: the mean daily dietary intake level of vitamin C of lead workers was 65.9mg (94% RDA), while that of controls was 132.6mg(189% RDA) ; and the serum vitamin C status of lead workers (0.10mg/dl) was significantly lower than that of controls (1.08mg/dl ; p<0.001). Both dietary vitamin C intake and serum vitamin C levels showed a significant negative correlation with blood lead level (p<0.001), which indicates that strategies of dietary management to promote the health of Korean lead workers should focus on promoting the vitamin C intakes of individuals.

• 농촌계획
• /
• 제15권4호
• /
• pp.135-146
• /
• 2009

Urban forest area in South Korea has been increased up to 20.8% of national land as of 2007 by the mergence of municipalities and counties. The rate of park and green tract among urban forest averages out to about 4% nationally but the Capital, Seoul, almost 105% level, not easy to split the two. Park and green has positive management system because of its infrastructure attribute and relevant security obligation standard while urban forest left alone with no such concerns. The most important reason of the negligence comes from institutional inertia although it is possible to be managed functionally by forest laws as like forests of park, landscape, wind and noise protection, and timber product. As a results, it reaches below than 92.64% of the national average level of the timber stockpile especially in the metropolitan areas and loses broad acres rapidly due to the easy conversion system to the urban land usage. Therefore, there must be required some alternative methodologies to conserve and foster it. The paper proposes the four urban forest management types and their control methods. The four types divide into conservation, foster, development, and reservation ones. Also it suggests the five furtherance tract types with the combination among the four earlier types, optionally having one of the six aim climaxes and recommends the standardization of operation design. The total green quantity index of urban forest also suggested by the weight method according to location and DBH class. The case study of the suggested model was executed on the Daejon Metropolitan area and its index calculated as 110.4% level compared with the acreage.

• The Journal of Asian Finance, Economics and Business
• /
• 제6권4호
• /
• pp.27-35
• /
• 2019

The paper examines the level of disclosure on Islamic banks' performance in the United Arab Emirates (UAE). The data was collected through content analysis of annual reports and financial statements of all fully-fledged Islamic banks working in the UAE over the period 2009 to 2013. Return on Assets is used as a proxy for the performance of Islamic banks while disclosure index is used as a proxy for Islamic banks' disclosure. Also, predetermined variables are used in the study like Size, Deposits, Non-Performing Investments and Capital to Risk Weighted Assets Ratio. Two-Stage Least-Square regression method is used to check the interdependence relationships between disclosure and performance of Islamic banks in the UAE. The results show a significant relationship between performance and disclosure in the UAE Islamic banks. Our regression results show that Islamic banks with higher levels of disclosure lead to higher operating performance. Furthermore, the performance has a great impact on the level of disclosure which means Islamic banks with high performance measures will disclose more information for investors and other institutions in order to reduce the cost of equity and increase their values in the market. This study is considered as a battery for further studies in the relationship between disclosure and financial performance of Islamic banks at a global level.

• Earthquakes and Structures
• /
• 제13권4호
• /
• pp.365-375
• /
• 2017

Seismic risk management has two main technical aspects: to recommend the construction of high-performance buildings and other structures using earthquake-resistant designs or evaluate existing ones, and to prepare emergency plans using realistic seismic scenarios. An overview of seismic risk assessment methodologies in Croatia is provided with details regarding the components of the assessment procedures: hazard, vulnerability and exposure. For Croatia, hazard is presented with two maps and it is expressed in terms of the peak horizontal ground acceleration during an earthquake, with the return period of 95 or 475 years. A standard building typology catalogue for Croatia has not been prepared yet, but a database for the fourth largest city in Croatia is currently in its initial stage. Two methods for earthquake vulnerability assessment are applied and compared. The first is a relatively simple and fast analysis of potential seismic vulnerability proposed by Croatian researchers using damage index (DI) as a numerical value indicating the level of structural damage, while the second is the Macroseismic method.

• 한국지반공학회논문집
• /
• 제23권11호
• /
• pp.59-66
• /
• 2007

자갈혼합재료의 역학특성에 미치는 자갈혼합율의 영향을 분석하기 위하여 화강풍화토를 이용한 대형 일차원압축시험을 실시하였다. 본 연구에서는 일본 야마구치현(山口縣) 시모노세키시(下關市)에서 채취한 화강풍화토를 이용해 입도를 조절한 후 일정한 다짐에너지로 다짐한 공시체를 시험에 사용하였다. 시험결과, 동일한 함수비에서 동일한 다짐에너지로 다짐을 실시하여도 자갈혼합율에 따라 서로 다른 건조밀도를 보였고, 이로부터 최대건조밀도를 나타내는 자갈혼합율이 존재하는 것과 이 자갈혼합율에서 최소의 압축지수를 보이는 것을 확인하였다. 또한 본 연구에서는 이상혼합체이론(two-phase mixture theory)을 이용해 자갈혼합율의 영향을 정량적으로 평가할 수 있는 방법을 제안하였고, 제안한 방법을 통해 산정한 초기건조밀도와 재료정수는 실내시험으로부터 얻은 실측값을 정확히 추정하는 것으로 평가되었다.

• 한국기계가공학회지
• /
• 제17권6호
• /
• pp.7-15
• /
• 2018

We propose a method for evaluating sound quality quantitatively to develop high-level home appliances (HA). Generally, a refrigerator has diverse movable parts such as slider, drawer, and folding shelf. Therefore, an engineering treatment to control the noise quality is considered as one of key technologies for a higher level refrigerator. Among the movable parts, we have selected a folding shelf as an example, which is commonly setup inside of a home refrigerator for increasing space convenience, to control the noise quality. However, it is known that its noise level is very high comparing to other movable parts when folding or unfolding actions. In order to evaluate and compare the noise quality, we have tested different eighteen models, and have suggested an impact sound quality index (ISQI) based on subjective evaluation data obtained experimentally by thirty two evaluators. The ISQI was formulated using three sound quality elements (noise peak, raising time, impact duration) to determine psycho-acoustic properties. Through this work, we developed an evaluating process and ISQI that was verified the usefulness by comparing the test results of personal perceptions given by evaluators with the prediction value of ISQI. We showed a good relations between them, so we believe that the proposed method and ISQI can be utilized to control of the noise quality of HA effectively.