• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.15 no.3
• /
• pp.453-462
• /
• 2002

Discrete-sizing or standardized steel profiles are used in steel design and construction practice. However, most of numerical optimization methods follow additional step(round-up discrete-sizing routine) to use the standardized steel section profiles, and accordingly the optimality of the resulting design nay be doubtful. Thus, in this paper, an efficient multi-level optimization algorithm is proposed to improve the shortcoming of the conventional optimization methods using the round-up discrete-sizing routine. Also, multi-level optimization technique with a decomposition method that separates both system-level and element-level is incorporated in the algorithm to enhance the performance of the proposed algorithms. The proposed algorithm is expected to achieve considerable improvement on both the efficiency of the numerical process and the accuracy of the global optimum.

• Proceedings of the Korea Society for Simulation Conference
• /
• 1999.04a
• /
• pp.110-114
• /
• 1999

본 연구는 Zeigler가 제안한 이산 사건 시스템 형식론(DEVS: Discrete Event System Specification)을 이용한 거시적 및 미시적 교통류 시뮬레이션 방법론의 개발을 주 목적으로 한다. 도로 교통망의 모델링 방법은 미시적(microscopic)방법과 거시적(macroscopic)방법으로 분류된다. 이러한 모델링 방법들은 그 목적에 따라 각기 표현되어 제각기 사용되어 왔으나, 시스템 이론적으로 이들은 독립적 모델이 아니며 오히려 이들은 서로 동질적 추상화 관계에 있어서, 통합 모델링 환경의 구축시 미시적 모델들로부터 추상화에 의한 거시적 모델의 자동생성 등 설계상의 효율뿐 아니라 모델간의 일관성을 통한 모델 유효성을 보장할 수 있는 장점이 제공될 수 있다. 따라서, 본 논문에서는 서로 다른 표현 방법(즉, 이산시간 형식론과 이산사건 형식론)간의 통합 표현을 기반으로 양자간의 추상화 관계를 도출하고, 이를 이용한 모델 추상화를 통해 거시적 및 미시적 교통류 시뮬레이션 방법론을 제안한다. 시스템 이론적 접근을 토대로 접근한 통합 교통류 시뮬레이션 환경은 미국 Berkeley 대학 교통 연구소에서 개발한 SHIFT 등과 같은 최첨단 교통류 시뮬레이션 도구에 비하여 SES/MB를 기반을 시스템 이론적이며 소프트웨어공학적인 접근을 통하여, 1) 기존 제어 방식의 검증 및 신뢰도 분석, 2) 각종 사건, 사고의 시간별 파급효과 분석, 3) 도로건설 계획안에 대한 타당성 검토, 4) 운전자 및 관리자를 위한 예측된 교통정보 등을 제공할 수 있을 것으로 기대된다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.5
• /
• pp.1078-1084
• /
• 2010

This paper presents a speech enhancement system which restores the amplitude components and phase components by discrete Fourier transform (DFT), using neural network training by back-propagation algorithm. First, a neural network is trained using DFT amplitude components and phase components of noisy speech signal, then the proposed system enhances speech signals that are degraded by white noise using a neural network. Experimental results demonstrate that speech signals degraded by white noise are enhanced by the proposed system using the neural network, whose inputs are DFT amplitude components and phase components. Based on measuring spectral distortion measurement, experiments confirm that the proposed system is effective for white noise.

• Journal of Korean Society of Steel Construction
• /
• v.17 no.4 s.77
• /
• pp.385-394
• /
• 2005

In this paper, a discrete optimum design program was developed using the refined fuzzy-genetic algorithms based on the genetic algorithms and the fuzzy theory. The optimum design in this study can perform section and shape optimization simultaneously for planar and spatial steel structures. In this paper, the objective function is the weight of steel structures and the constraints are the design limits defined by the design and buckling strengths, displacements, and thicknesses of the member sections. The design variables are the dimensions and coordinates of the steel sections. Design examples are given to show the applicability of the discrete optimum design using the improved fuzzy-genetic algorithms in this study.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.34 no.8
• /
• pp.1258-1264
• /
• 2005

We determined the effect of chlorine dioxide ($ClO_{2}$) treatment on microbial growth and quality of saury. Saury samples were treated with aqueous $ClO_{2}$ at 3, 10, and 50 ppm. After the treatment, saury samples were stored at -20$^{\circ}C$ and 4$ ^{\circ}C$, respectively. Saury samples treated with $ClO_{2}$ had significantly lower total bacterial counts during storage. In particular, treatment of 50 rpm $ClO_{2}$ decreased total bacterial count most significantly among the $ClO_{2}$ treated saury samples. After 4 days, populations of total bacteria for the control reached 6.43 log CFU/g, while the sample treated with 50 ppm of $ClO_{2}$ had 5.47 log CFU/g at the 9th day of storage. $ClO_{2}$ treatment also delayed increase in the population of psychrotrophic bacteria on saury. The pH of saury samples decreased with increase of $ClO_{2}$ concentration. Volatile basic nitrogen (VBN) and thiobarbituric acid reactive substance (TBARS ) values of saury samples increased during storage, regardless of $ClO_{2}$ concentration. Sen-sory evaluation of saury samples showed that treatment with $ClO_{2}$ could improve the quality of saury. These results indicate that $ClO_{2}$ treatment could be useful in improving microbial safety and quality of saury.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.19 no.1
• /
• pp.17-27
• /
• 2013

The effects of chlorine dioxide gas ($ClO_2$) treatments between high-concentration-short-time and low-concentration-long-time on maintaining the quality of cherry tomatoes (Lycopersicon esculentum Mill. cv 'unicorn') were investigated. Tomatoes were treated with 5 ppm for 10 min and 10 ppm for 3 min as high-concentration-short-time $ClO_2$ gas treatment conditions and 1 ppm for once a day interval in terms of low-concentration-long-time $ClO_2$ gas treatment condition, respectively. After $ClO_2$ gas treatments, tomatoes were storage at 5 and $23^{\circ}C$ for 7 days. Weight loss, changes in tomato color, firmness, soluble solids content, pH, growth of total microorganism, and decay rate were evaluated. On day 7, tomatoes treated with chlorine dioxide gas showed low values of respiratory rate, total microbial growth, and decay rate compared to those of tomato without chlorine dioxide gas treatment. Additionally, tomatoes treated the chlorine dioxide were kept the values of firmness and soluble solids content during storage. However, chlorine dioxide gas treatment on tomatoes had no direct effect on weight loss, pH, and color. Results showed that both $ClO_2$ concentration and treatment time played the important roles for keeping the quality of tomatoes during storage. Tomatoes with chlorine dioxide gas treatment of low-concentration-long-time had more effective values of firmness, the total microbial growth, and decay rate than those with two chlorine dioxide gas treatments of high-concentration-short-time. Results suggest the potential use of chlorine dioxide gas treatment of low-concentration-long-time as an highly effective method for keeping the freshness of cherry tomato.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.12
• /
• pp.1622-1627
• /
• 2007

This study was undertaken to evaluate the effects of chlorine dioxide on reducing E. coli O157:H7 and L. monocytogenes on broccoli served in foodservice institutions. Broccoli samples inoculated with $10^6$ CFU/mL of E. coli O157:H7 and L. monocytogenes were treated with chlorine dioxide. Treatments with 5, 10, and 20 ppm for 1, 5, and 10 min were not sufficient in controlling E. coli O157:H7 on broccoli. L. monocytogenes were effectively reduced by $2.19{\sim}2.48log\;CFU/g\;and\;3.31{\sim}3.87log\;CFU/g$ with 10 and 20 ppm chlorine dioxide for 1, 5, and 10 min treatment, respectively, compared with the control. E. coli O157:H7 and L. monocytogenes population were significantly negatively correlated with concentration and treatment time of chlorine dioxide. These results show that the use of chlorine dioxide was effective in sanitizing L. monocytogenes on broccoli and the level of concentration was more associated with populations of E. coli O157:H7 and L. monocytogenes than treatment time of chlorine dioxide on broccoli.

• Korean journal of applied entomology
• /
• v.56 no.2
• /
• pp.147-152
• /
• 2017

Heart contraction is essential for insect hemolymph circulation, in which various physiological changes need control of the heart contraction. Thus, interruption of heartbeats intimidate insect survival. Chlorine dioxide induces release of reactive oxygen species (ROS), which has been regarded as the main insecticidal agent. This study analyzed the effect of chlorine dioxide on heartbeats of the Indianmeal moth, Plodia interpunctella. The larvae have the dorsal vessel on the medial dorsal region in a form of an extending tube from the first thorax to 10th abdominal segment. Dorsal vessel contraction was noticeable between 3rd and 10th abdominal segments, where five heart chambers were observed. Average heartbeat rate was 118.6 beats per min at $25^{\circ}C$. However, the heartbeats varied with ambient temperature. Injection of chlorine dioxide to hemocoel suppressed the heartbeats in a dose-dependent manner. The suppressive effect of chlorine dioxide also increased with exposure time to gas form of the chemical at 100 ppm. However, vitamin E (an antioxidant against ROS) treatment significantly rescued the larvae treated with chlorine dioxide in the heart contraction activity. These results suggest that chlorine dioxide negatively influences on the heart contraction of P. interpunctella via its production of ROS.

• Korean journal of applied entomology
• /
• v.56 no.3
• /
• pp.253-259
• /
• 2017

Fumigation using chlorine dioxide ($ClO_2$) has been regarded as a potential control technique against stored grain insect pests. The control efficacy can be enhanced with increase of opening rates of spiracles by facilitating the toxic gas delivery to internal body. To test this hypothesis, this study used the Indianmeal moth, Plodia interpunctella, which was known to be susceptible to $ClO_2$, and analyzed the opening rate of spiracles. A total of 9 pairs of spiracles were observed in P. interpunctella larvae, in which one pair was located on the prothorax and eight pairs were on the abdomen. Within the body, the spiracles were connected to longitudinal and transverse tracheal trunks. The open spiracles were determined by the dye-infiltration method. Based on this method, the opening rate of spiracles increased up to about 60% with increase of ambient temperatures. Furthermore, exposure to carbon dioxide stimulated the opening rate of spiracles up to about 95%. In contrast, exposure to $ClO_2$ prevented the spiracle opening and resulted in only 25% of spiracles in an opening state. The addition of carbon dioxide to $ClO_2$ treatment rescued the opening rate of spiracles as much as the carbon dioxide single treatment. Based on this modulatory activity of carbon dioxide against spiracles, the combined treatment of $ClO_2$ with carbon dioxide resulted in significant increase of its toxicity against P. interpunctella compared to a single $ClO_2$ treatment.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.13 no.4
• /
• pp.165-170
• /
• 2011

The ambient concentrations of nitrogen dioxide ($NO_2$) at 65 forest areas were measured every month using passive diffusive samplers from 2002 to 2009 and were compared to those at urban areas in order to investigate the characteristics of temporal and spatial distributions of $NO_2$ from the forest and urban areas. The annually averaged concentrations of $NO_2$ gradually decreased for both areas. The average concentration of $NO_2$ in the forest areas was 8.0 ppb, which was lower than that in the urban areas (i.e., 19.4 ppb) and the ecological standard level of the European Union (i.e., 14.6 ppb). The monthly average of $NO_2$ concentration depicted seasonal variations particularly in the urban areas, showing higher concentration in winter and lower concentration in summer. Strong locality of $NO_2$ concentration distribution illustrates that the locations near the metropolitan areas (e.g., Gyeonggi and Chungnam provinces) had the highest concentration during the measurement period. A significant positive correlation between $NO_x$ emissions and $NO_2$ concentration was observed, suggesting that the magnitude and proximity to sources of atmospheric nitrogen oxides would be important controlling factors.