• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1284-1294
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• 2010

The ZigBee is one of the most important technologies for composing USN. It is one of the IEEE 802.15.4 standards to support personal area networks. It uses a hierarchical routing or an on-demand route discovery strategy as an address allocation method. A hierarchical routing doesn't use a routing table but only uses a child node or a parent node as an intermediate node for data delivery. Therefore, the ZigBee network's topology greatly affects the overall network performance. In this paper, we propose a more trustworthy algorithm than only using the depth and widely variable LQI during network formation, and moreover we propose an algorithm to measure network's trustworthiness. We simulate our algorithm using the NS-2 and implement our network using the MG2400 ZigBee module for verifying performance.

• Korean Journal of Community Nutrition
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• v.5 no.2
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• pp.185-192
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• 2000

As the percentage of the elderly in the population increases, research to identify the nutritional and health status of the elderly, to understand the factors influencing on them, and to delay aging have been done actively. It is necessary for these studies to be longitudinal. This study was carried out to assess the change of health-related habits such as dietary behaviors and smoking, alcohol drinking and exercising habit, and health status between previous study(1991/1994) and post study(1998) for middle-aged men and women living in Chonju. For the present study, the data of 63 pairs(23 men and 40 women) were analyzed. They were 11 men and 12 women followed up from 82 men and 100 women surveyed in 1994. Mean ages in the 1991/4 and 1998 studies were 53.6y(range 42-63y) and 59.0y(range 46-72y) respectively. The survey was conducted with interview using a questionnaire including dietary behaviors and health-related habits, and anthropometric measurement and blood test for analyzing biochemical indices in 1991/4 and 1998. To understand these changes over time, $\chi$$^2$-statistics, t-test and paired t-test were analyzed with an SAS package program. As people age, there were significantly decreases in the proportions to eat lightly salted foods and drink alcohol. Significant longitudinal increases in triceps skin fold thickness, ${\gamma}$-GPT and HDL-cholesterol and significant decrease in hemoglobin value were noted over time in both men and women. In addition a significant decrease in blood glucose level was noted over time in women. Weight, blood glucose and total cholesterol increased significantly with age in those had had breakfast regularly or those had not used more slat at the table in the past. From this study, were found out the subjects of this study had relatively desirable health-related habits. But as improper health-related habits are likely to result in inappropriate health status(eg, increase in WHR, triglyceride, total cholesterol and LDL-cholesterol), it is recommended that nutrition education in necessary as soon as possible to meet the health elderly.

• Korean Journal of Remote Sensing
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• v.26 no.6
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• pp.605-615
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• 2010

This study demonstrates the feasibility of small satellite, namely PROBA platform with the compact high resolution imaging spectrometer (CHRIS), for aerosol retrieval in Hong Kong. The rationale of our technique is to estimate the aerosol reflectances by decomposing the Top of Atmosphere (TOA) reflectances from surface reflectance and Rayleigh path reflectances. For the determination of surface reflectances, the modified Minimum Reflectance Technique (MRT) is used on three winter ortho-rectified CHRIS images: Dec-18-2005, Feb-07-2006, Nov-09-2006. For validation purpose, MRT image was compared with ground based multispectral radiometer measurements and atmospherically corrected Landsat image. Results show good agreements between CHRIS-derived surface reflectance and both by ground measurement data as well as by Landsat image (r>0.84). The Root-Mean-Square Errors (RMSE) at 485, 551 and 660nm are 0.99%, 1.19%, and 1.53%, respectively. For aerosol retrieval, Look Up Tables (LUT) which are aerosol reflectances as a function of various AOT values were calculated by SBDART code with AERONET inversion products. The CHRIS derived Aerosol Optical Thickness (AOT) images were then validated with AERONET sunphotometer measurements and the differences are 0.05~0.11 (error=10~18%) at 440nm wavelength. The errors are relatively small compared to those from the operational moderate resolution imaging spectroradiometer (MODIS) Deep Blue algorithm (within 30%) and MODIS ocean algorithm (within 20%).

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.4
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• pp.246-254
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• 2015

This study explored the effect of rainfall pattern and soil characteristics on water management in rice paddy fields, using a soil water balance model, BUDGET. In two sites with different soil textural group, coarse loamy soil (Gangseo series) and fine soil (Hwadong series), respectively, we have monitored daily decrease of water depth, percolation rate, and groundwater table. The observed evapotranspiration (ET) was obtained from differences between water depth decrease and percolation rate. The root mean square difference values between observed and BUDGET-estimated ET ranged between 10% and 20% of the average observed ET. This is comparable to the measurement uncertainty, suggesting that the BUDGET model can provide reliable ET estimation for rice fields. In BUDGET model of this study, irrigation requirement was determined as minimum water need for maintaining water-saturated soil surface, assuming 100 mm of bund height and no lateral loss of water. The model results showed different water balance and irrigation requirement with the different soil profile and indicated that minimum percolation rate by plow pan could determine the irrigation requirement of rice paddy field. For the condition of different rainfall distribution, the results presented different irrigation period and amounts, representing the importance of securing water for irrigation against different rainfall pattern.

• Journal of Biomedical Engineering Research
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• v.41 no.6
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• pp.219-227
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• 2020

In this study, we tried to quantify the actual cross-sectional area inside the bore when scanning by the MRI system with various bore sizes. To this end, a comparative analysis was conducted by both of blueprint of each MRI equipment and actual measurement in the field. As a result of analysis, ACSA(Actual Cross-Sectional Area) in Ingenia CX, Elition X, uMR 780, Omega, Vida, Lumina, Architect, Premier is recorded as 171230, 232150, 242100, 309332, 230760, 230760, 229380 and 235990 ㎟, respectively ACSA% was 60.6, 60.3, 73.0, 70.0, 60.0, 60.0, 59.6, and 61,3%. In addition, DTB (Distance from Table top to Bore top) recorded 400, 407, 445, 495, 405, 405, 405, 403, and 412 mm. Through this study, it was confirmed that there is a difference between the bore size according to each MRI system and the actual cross-sectional area during MRI scanning. Accordingly, if we consider the internal actual area just not bore size at the clinical site, useful diagnostic images can be obtained in the end with better convenience.

• Journal of Korea Trade
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• v.25 no.2
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• pp.58-74
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• 2021

Purpose - This paper research on the embodied carbon emission in Sino-Korea trade. It calculates and analyzes the carbon emission coefficient and specific carbon emissions in Sino-Korea trade from 2005 to 2014. Design/methodology - This paper conducted an empirical analysis for embodied carbon emission in Sino-Korea trade during the years 2005-2014, using a multi-region input-output model. First, direct and complete CO2 emission coefficient of the two countries were calculated and compared. On this basis, combined with the world input-output table, the annual import and export volume and sector volume of embodied carbon emission are determined. Then through the comparative analysis of the empirical results, the reasons for the carbon imbalance in Sino-Korea trade are clarified, and the corresponding suggestions are put forward according to the environmental protection policies being implemented by the two countries. Findings - The results show that South Korea is in the state of net trade export and net embodied carbon import. The carbon emission coefficient of most sectors in South Korea is lower than that of China. However, the reduction of carbon emission coefficient in China is significantly faster than that in South Korea in this decade. The change of Korea's complete CO2 emission coefficient shows that policy factors have a great impact on environmental protection. The proportion of intra industry trade between China and South Korea is relatively large and concentrated in mechanical and electrical products, chemical products, etc. These sectors generally have large carbon emissions, which need to be noticed by both countries. Originality/value - To the best knowledge of the authors, this study is the first attempt to research the embodied carbon emission of ten consecutive years in Sino-Korea Trade. In addition, In this paper, some mathematical methods are used to overcome the error problem caused by different statistical caliber in different databases. Finally, the accurate measurement of carbon level in bilateral trade will provide some reference for trade development and environmental protection.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.1
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• pp.95-101
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• 2022

This paper proposes a method to process the shape of an optical transmission road and attempts to determine the most suitable single processing method for an acrylic plate optical transmission road. In addition, by manufacturing an automatic pattern processing device to generate certain shapes on the acrylic plate at regular intervals, and measuring the illuminance of the patterned acrylic plate optical transmission road, the measured illuminance was confirmed to fall under the KS illuminance values presented in Table 1. In conclusion, when an incident light of approximately 20,000 lx is applied, the transmission illumination is approximately 200 lx, which represents a transmission rate of approximately 1% for incident light and corresponds to the KS illumination criterion F. Additionally, the right-angle triangular pyramid base size (A) processed at a temperature of 350 ℃ for one second was 2 mm, exhibiting the largest transmission illumination of 280 lx. When the transparent acrylic plate was set to a constant size of 1.6 mm at the bottom of the right-angle triangular pyramid, the fastest response occurred at a processing tip temperature of 350 ℃ (0.04 s). On the other hand, it took 10 s to process the size of the bottom of the right-angled triangular pyramid at a temperature of 200 ℃ to 1.6 mm, and it was confirmed that the optical transmission efficiency was significantly reduced because of the burr that occurred at this time.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.591-596
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• 2022

Since 4-bar linkage widely used in various industrial fields has a fixed link length, it is inconvenient to add an independent link structure or control device to change the movement of output link. Therefore, this paper proposes a new concept of variable 4-bar linkage mechanism to selectively adjust the movement of the output link to fit desired situations, and applied to the commercial table fans, which is a representative product using a 4-bar linkage system. The optimal rotation angle steps for efficiency are determined experimentally and the appropriate lengths of linkage to fit each step are calculated analytically. Changes in the linkage length are implemented by the rotational motion using a grooved cylindrical cam and the feasibility of the proposed variable linkage mechanism is verified through fabrication and measurement. The presented variable link mechanism is expected to improve the efficiency of industrial robots and fuel valve systems.

• Journal of the Korean GEO-environmental Society
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• v.24 no.1
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• pp.45-50
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• 2023

In order to prevent slope disasters caused by rainfall, it is very important to quickly exclude rainfall. In Korea, horizontal drainage holes with excellent economic feasibility and construction performance are generally applied as a method to lower the underground water level. However, horizontal drainage holes constructed on the site are often uniformly constructed regardless of the presence or absence of other water or ground conditions, and it is often difficult to expect drainage performance of horizontal drainage holes due to poor maintenance. In this study, an artificial ground was created using model construction and horizontal drainage experiments were conducted to measure the amount of horizontal drainage drain in a certain amount of control area 0%, 25%, 50%, 75%, and an evaluation table (draft) that can quantitatively evaluate horizontal drainage based on measurements and design documents is proposed as basic data.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.489-502
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• 2022

This paper is aimed at developing an optimization-based Finite Element model updating approach for structural damage identification and quantification. A modal flexibility-based error function is introduced, which uses modal assurance criterion to formulate the updating problem as an optimization problem. Because of the inexplicit input/output relationship between the candidate solutions and the error function's output, a robust and efficient optimization algorithm should be employed to evaluate the solution domain and find the global extremum with high speed and accuracy. This paper proposes a new multi-stage Selective Particle Swarm Optimization (SPSO) algorithm to solve the optimization problem. The proposed multi-stage strategy not only fixes the premature convergence of the original Particle Swarm Optimization (PSO) algorithm, but also increases the speed of the search stage and reduces the corresponding computational costs, without changing or adding extra terms to the algorithm's formulation. Solving the introduced objective function with the proposed multi-stage SPSO leads to a smart feedback-wise and self-adjusting damage detection method, which can effectively assess the health of the structural systems. The performance and precision of the proposed method are verified and benchmarked against the original PSO and some of its most popular variants, including SPSO, DPSO, APSO, and MSPSO. For this purpose, two numerical examples of complex civil engineering structures under different damage patterns are studied. Comparative studies are also carried out to evaluate the performance of the proposed method in the presence of measurement errors. Moreover, the robustness and accuracy of the method are validated by assessing the health of a six-story shear-type building structure tested on a shake table. The obtained results introduced the proposed method as an effective and robust damage detection method even if the first few vibration modes are utilized to form the objective function.