• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.2
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• pp.219-226
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• 2013

Against the global eavesdropping in wireless sensor networks, tremendous amount of dummy packets for faking are likely to be continuously generated in order to keep the location privacy of the communication source and destination. In our approach only certain disk-shaped zones of encompassing sources and destination are allowed to issue dummy packets during the data transfer so that the amount of generated packets is reduced while the location privacy of the source and destination remains secret. To this end we design a routing protocol and propose a detailed formal specification of it, and verify major characteristics.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.433-438
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• 2020

Nodes on a data communication path in a wireless network emit electro-magnetic waves whenever they transmit packets; thus, the path can be exposed and identified with capturing and analyzing a sequence of the signals emitted there. One of countermeasures against a malicious eavesdropper is to let certain nodes mimic the nodes on the data path in sending dummy packets. In this paper we propose a packet transfer protocol which establishes the shortest path between source-destination pair a time and restricts heavy generation of dummy packets. We verify the location-privacy of a node on the communication paths through simulation.

• Journal of Aerospace System Engineering
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• v.12 no.5
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• pp.24-31
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• 2018

The objectives of this study is to carry out Bird strike analysis and tests of a blade antenna of aircraft. FEMs (Finite Element Models) were created for the analysis, while dummy and real antennas were used for the bird strike tests. In the analysis, birds were modeled with SPH (Smooth Particle Hydrodynamics) method, and the behaviors of the bird, antenna, and joint structure between antenna and aircraft fuselage were simulated with the FSI (Fluid-Structure Interaction) method. After the bird strike test was performed, the results of the analysis and test showed that they had a positive relationship. The damage of antenna and bolted joint was checked, and the structural integrity of the airframe was proved.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.05a
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• pp.649-652
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• 2019

최근에 카메라를 사용하여 물체를 인식하고 수량을 측정하는 연구가 진행되고 있다. 하지만 건축 자재와 같이 인접한 동일 물체의 경우, 인식과 측정이 어려우며, 이와 관련된 연구는 부족한 실정이다. 본 논문에서는 이러한 문제를 해결하기 위해 딥러닝과 드론을 사용하는 방법을 통하여 자재 더미의 윗면과 측면의 촬영, 드론 로그를 사용하한 드론 높이와 Yaw값 획득, 영상 내 자재 종류와 영역 정보 등 미리 학습된 딥러닝 모델을 사용한 획득방법, 드론 촬영 시의 Yaw값 차이를 이용해 윗면과 측면이 공통으로 가지는 직선 검색, 자재 더미의 가로, 세로, 높이의 비율 등을 통한 각 화소 비율과 자재 개수의 영역별 가상의 체적값 분석, 드론의 화각, 높이를 사용한 체적 사진측량값 획득, 가상 체적과 사진측량법 사이의 오차 최소화 비율 등을 연구하였다.

• Resources Recycling
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• v.9 no.6
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• pp.53-57
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• 2000

In the present paper, a current technical progress for recycling of used steel can is described. The developed technology was a kind of pre-treatment through an automatic equipment system to increase recycling and melting efficiency of used steel co. The process consisted of several unit processes such as breaking of steel can bale, removing dust, separation of aluminum can, delacquering, and compressing to bale. Also, aluminum powders were recovered as a by-product at the delacquering step. The process was carried out automatically through by use of the developed equipment system. The automatic system could be very available in mass treatment of used steel can.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.11 no.6
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• pp.111-122
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• 2016

Support and efforts are being strengthened at the national level for entrepreneurial activities that are expected to revitalize our economy. Generally, according to the previous studies, it is known that entrepreneurship positively affects economic growth and the reduction of unemployment rate through employment creation. The analysis of the impact of entrepreneurial activities on economic growth and job creation is mainly based on national comparative analysis. In this paper, however, the impact of start-up activities in the Busan metropolitan city on regional economic growth and employment improvement. In this study, the dummy variables were assigned to firms within three years, five years, and ten years after start-up according to the period since the start-up of the firm. As a result of the empirical analysis, the value of dummy variable of the start - up firms was found to be significant in the analysis of the sales growth rate as the dependent variable according to the preceding study by Evans(1987). Therefore, it can be seen that the growth rate of the start - up company is higher than that of the other companies and it is positive for the regional economic growth. In addition, the coefficient of the dummy variable decreases from the enterprise analysis to the latter within three years, five years, and ten years after the start-up, and confirms that the coefficient of the firm's start-up years has a negative value. I could see more clearly. On the other hand, in the analysis of the effect of start-up firms on unemployment rate reduction, the growth rate of regular workers was higher than that of other firms. This suggests that it positively affects the reduction of the unemployment rate in the region. In addition, in the dynamic analysis using the Almon estimation formula and the Koyck model, the effect of log-transformed net start-up firms on the growth rate of new workers is very significant. As a result of the above model, It is reaffirmed that start-up activity has a positive effect on employment growth.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.4
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• pp.112-117
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• 2002

This study was conducted to induce the optimal composting conditions of pig manure mixed with sawdust and dried paper-mill sludge in the composting for production of high quality compost. Pig manure contains high water content and How C/N ratio because of comparatively high nitrogen content than sawdust and dried paper-mill sludge. Therefore the addition of dried paper-mill sludge and sawdust to the raw materials helps controlling the C/N and the water content of compost pile. The composting system used in the experiment was agitated static bed system. The physical properties of the mixed raw materials was not good at the working conditions in the early stage of composting. The temperature of compost heap reaches at $60^{\circ}C$within 5 day after starting composting in P-2 treatment mixed with pig manure and sawdust(56.6 : 43.4). Then the water content of P-2 was 58%. The pH in all treatments were slowly decreased as the composting was proceeded. Although the changes of T-C and T-N were not extended because of the short composting experiment period. Reduction rates of T-C in treatments were 5-12% without special difference. By considering the efficiency of composting in each of five treatments with pig manure the optimal water contents was about 57% level. Mixing a sawdust as a bulking agent was more positive than dried paper-mill sludge from a viewpoint of compost quality.

• Korean journal of applied entomology
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• v.20 no.4 s.49
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• pp.217-222
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• 1981

As a primary study on the economic injury level of A. tokionis larval populations in tobacco fields, we carried out some experiments for the evaluation of sampling efficiency of 3 sampling methods (pit-fall traps of apple pomace and rice bran, and clover patches) for the larval population and the regressions between loss and infested larval density The $10\times10cm$ clover patch showed a better sampling efficiency $11.8\;to\;18.0\%$ than the others. The sampling efficiency of clover patch becomes higher when the plots did not have any green plants. The linear regression equation (Y=4.2+1.383x) between loss (Y:kg/10a) and infested larval density (X: no. of larvae/plot) which was obtained by substitution of damage ratio and corrected damage ratio fitted the observed data better than the one (Y=2.68X) obtained without substitioning.

• Science of Emotion and Sensibility
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• v.21 no.1
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• pp.35-44
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• 2018

This study suggests the sensing method of the Three-dimensional respiration rate sensor based on surface area changes, and exploring the design direction of the three-dimensional breathing sensor and the design orientation of the garment. To achieve this, two types of three-dimensional respiration rate sensor were produced, and the study of the dummy and the subjects studied. The study I investigated the possibility of measurement of the three-dimensional respiration sensor by the study variables of the sensor type and speed of respiration. The study II proposes a suitable type of sensor for each of the three measuring positions in addition to the study variables in the study I. To evaluate accuracy, reproducibility, and reliability of the three-dimensional respiration rate sensor, the BIOPAC was used to measure the respiration rate simultaneously with the three-dimensional respiration rate sensor. Through all these results of the experiment, it explored the possibility of measurement of the three-dimensional respiration sensor for the dummy. It also proposed a suitable type of sensor by measuring the respiration rate for the human body.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.284-289
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• 2009

This study estimated the fiberboard demand using VAR and econometric model, and compared the prediction accuracy of the two models. And the variance decomposition and impulse response were analyzed using VAR model, and predicted the fiberboard demand. The VAR model was specified with lagged dependent variable, lagged own price, lagged construction product, dummy. The econometric model was specified with own price, substitute price, construction product, dummy. The dummy variable reflected the abrupt decrease in fiberboard demand in the late 1990's. The results showed that the fiberboard demand prediction can be performed more accurately by VAR model than by econometric model. In the VAR model of fiberboard demand, after twelve months, the construction product change accounts for about fifty percent of variation in the demand, and the own price change accounts for about thirty percent of variation in the demand. On the other hand, the impact of a shock to the construction product is significant for about twelve months on the demand of fiberboard, and the impact of a shock to the own price is significant for about six months on the demand of fiberboard.