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정성택,박종남,김선진,조규재 한국공작기계학회 2002 한국공작기계학회 춘계학술대회논문집 Vol.2002 No.-
In recent days the more use of CFRP composite is in the airplane, automobile, and sport goods, etc., the more necessity of research on it in this engineering. In this research, the CFRP composite specimen are fabricated by 48 CFRP plies with 8 orientation angles, and the specimens are drilled with 3 tools. The results are analyzed with consideration of cutting force, type of tools and fabrication condition. The specimens with each drilling conditions are also investigated with SEM. The optimal drilling conditions such as drill types and cutting force with respect to the fabricating condition are studied.
지성민,서용칠,구교진,현창택 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2
In terms of the Safety, a risk of accident in construction industry is the most dangerous thing in any other industries. So, there have been many studies to improve the safety performance of construction projects. But, the most of them were dealt with controls in the job site and the contractor. For these reasons, the purpose of this study(Construction Safety Management) is two-part. : One is showing the basic items composed of prequalification in Construction Safety Management, and the other is improving the selection method to meet the owner's needs including a Contractor's Safety Management Performance.
Al-Zn-Mg-Cu-Zr 합금의 집합조직 발달과 기계적 특성에 미치는 Sc 첨가의 영향
제창웅,진승준,정동석,임성택,이용연,박노진 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.10
The texture and mechanical properties during fabrication processes - extrusion, cold rolling and aging treatment - of plate in the 7050 Al alloys without/with 0.1%Sc were investigated. In both the cross section(CS) and longitudinal section(LS) of the specimen without Sc, after cold rolling, texture of R-fiber was predominant. In the Sc added alloy after cold rolling, {112}<111>(Cu)+weak (123)<634>(S) texture components developed in the CS of the specimen while strong (3-fiber+(110)<001>(Goss) components developed in the LS of the specimen. After solution treatment and aging treatment, the alloy (CS and LS) without Sc had random texture, but by the alloys with the 0.1%Sc, the components of the rolling texture are not changed. After the aging treatment, hardness and tensile strength of the alloy with 0.1%Sc increased about 15% and 17%, respectively, than those without Sc. Tensile strength of the Sc added specimen was the highest along the rolling direction where the <111> texture was strongly developed. On the other hand, in the specimen without Sc, the mechanical properties were not dependent on the direction of the sample. (Received May 3, 2004)
Estimation of Soil Organic Carbon (SOC) Stock in South Korea Using Digital Soil Mapping Technique
Seong-Jin Park,Soon-Ik Kwon,Seong-Heon Kim,Jaehong Shim,Yun-Hae Lee,Taek-Keun Oh 한국토양비료학회 2021 한국토양비료학회지 Vol.54 No.2
Estimation of soil organic carbon (SOC) stocks is highly relevant considering that SOCs is the central driver in soil fertility and climate change mitigation. This study aims to (i) evaluate the SOC stock in the first 0 - 30 ㎝ and 0 - 100 ㎝ soil layer on a national scale from spatially explicit explanatory environmental variables and a legacy soil database and (ii) the spatial distribution of SOCs at national scale through digital mapping technique. A spatial model was established using Cubist, a decision tree algorithm and based on soil data (s factor), climatic (c factor), topographic (r factor). Results showed that soil texture, soil parent, mean annual precipitatio and elevation were the most important predictors of SOCs. The Cubist prediction model had a Root Mean Squared Error (RMSE) equal to 19.5 at 0 - 30 ㎝, 68.7 at 0 - 100 ㎝. The predicted mean SOC stock from fitted models was 35 ton C ㏊<SUP>-1</SUP> for 0 - 30 ㎝ depth, 87 ton C ㏊<SUP>-1</SUP> for 0 - 100 ㎝ soil depth. In total, soil stored approximately 330 Mt C for 0 - 30 ㎝ depth and 842 Mt C for 0 - 100 ㎝ depth.
Analysis of Theoretical Bounds in Noisy Threshold Group Testing
Jin-Taek Seong 한국정보과학회 2022 Journal of Computing Science and Engineering Vol.16 No.3
The objective of this study was to describe a noisy threshold group testing model where positive and negative cases could occur depending on virus concentration in coronavirus disease 2019 (COVID-19) diagnosis with output results flipped due to measurement noise. We investigated lower bounds for successful reconstruction of a small set of defective samples in the noisy threshold group testing framework. To this end, using Fano’s inequality, we derived the minimum number of tests required to find unknown signals with defective samples. Our results showed that the minimum number of tests on probability of error for reconstruction of unknown signals was a function of the defective rate and noise probability. We obtained lower bounds for performance of the noisy threshold group testing framework with respect to noise intervals. In addition, the relationship between defective rate of signals and sparsity of group matrices to design optimal noisy threshold group testing systems is presented.
Predicting the Performance of Cooperative Wireless Networking Schemes With Random Network Coding
Jin-Taek Seong,Heung-No Lee Institute of Electrical and Electronics Engineers 2014 IEEE Transactions on Communications Vol. No.
<P>In this paper, we consider a cooperative wireless network in which there are multiple sources and multiple relays. Owing to unreliable wireless channels, the quality of network links between nodes can vary. This results in the failure of intermediate nodes that generate linear combinations of incoming messages in network coding schemes. We propose an analytical framework to evaluate the recovery performance of source messages at the base station. To this end, we consider a random transmission matrix in which each element of the transmission matrix is processed a random variable, where its distribution is a function of the outage probability. We derive an upper bound for the reconstruction performance, i.e., decoding failure probability and nullity. The proposed framework provides an evaluation tool that enables us to investigate the impact of a large number of sources and relays, as well as the field size of the network codes on system performance.</P>