• 산업경영시스템학회지
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• 제34권2호
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• pp.1-8
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• 2011

This paper proposes a variable sampling interval multivariate $T^2$ control chart with sampling at fixed times, where samples are taken at specified equally spaced fixed time points and additional samples are allowed between these fixed times when indicated by the preceding $T^2$ statistics. At fixed sampling points, the $T^2$ statistics are composed of all quality characteristics and a part of quality characteristics are selected to obtain $T^2$ statistics at additional sampling points. A Markov chain approach is used to evaluate the performance of the proposed chart. Numerical studies for the performance of the proposed chart show that the proposed chart reduces the observations obtained from a process and detects the assignable cause of a process with low correlated quality characteristics quickly.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.977-982
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• 2000

As a newly structural system, RCS composite system has been researched last two decades. However mechanism of exterior T-type joint for RCS composite system is not well known. This research is focus on the exterior T-type joint for RCS composite system. Specimens are designed by the ASCE guideline, tested and compared with the inner RCS joint. Test variables include face bearing plate(FBP), extended face bearing plate(E-FBP) and U-bar. The tests indicate that the strength of exterior T-type joint is higher than that of the guideline by ASCE. The U-bar has a significant effect on the joint strength and absorbing the strain energy.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2012년도 한국컴퓨터종합학술대회논문집 Vol.39 No.1(C)
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• pp.286-288
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• 2012

Facing the counterfeiting acts towards various products, many manufacturers implement ePedigree system to secure their supply chain. Using ePedigree, a distribution history including a valid product identifier from the manufacturer until the final retailer is recorded. And this ePedigree is signed by each involved supply chain party using digital signature. With this digital signature, any unauthorized alteration to the ePedigree document would generate a failed verification process. If there is a counterfeit product using a fake ePedigree document, it wouldn't be able to pass the verification process either. Hence, there wouldn't be any counterfeit product that could enter the legal supply chain and bought by the consumer. We are proposing to use ECDSA instead of RSA since it has faster performance and shorter key size. At a certain same security level, ECDSA only needs 163 bits, while RSA needs 1024 bits.

• Smart Structures and Systems
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• 제22권1호
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• pp.95-103
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• 2018

Active vibration control via inertial mass actuators has been shown as an effective tool to significantly reduce human-induced vertical vibrations, allowing structures to satisfy vibration serviceability limits. However, a lot of practical obstacles have to be solved before experimental implementations. This has motivated simple control techniques, such as direct velocity feedback control (DVFC), which is implemented in practice by integrating the signal of an accelerometer with a band-pass filter working as a lossy integrator. This work provides practical guidelines for the tuning of DVFC considering the damping performance, inertial mass actuator limitations, such as stroke and force saturation, as well as the stability margins of the closed-loop system. Experimental results on a full scale steel-concrete composite structure (behaves similar to a footbridge) with adjustable span are reported to illustrate the main conclusions of this work.

• 상하수도학회지
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• 제22권2호
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• pp.179-182
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• 2008

The KIDEA process, occurred in single reactor, is operated by three consequential steps, i.e., aerobic, settling, and discharge while introducing wastewater into the bottom of reactor continuously. It could accomplish biological oxidation (BOD), nitrification, denitrification (T-N), phosphate removal (T-P), and solid separation (SS) through the operational mode mentioned. Especially, this system has removed the T-P by wasting certain amount of sludge at the end of aeration phase during 5~10 minutes and not returned the activated sludge into the reactor, that is, no RAS (Return Activated Sludge). All running mode and instrumentation were controlled by the PLC equipment automatically. In this study, therefore, we have evaluated T-P removal efficiency and moisture content (MC) performance under the different excess sludge wasting mode. T-P track study and MC with TS concentration were analyzed during aerobic and settling phase. It has revealed that there was no significant difference of released T-P concentration between the first case which waste the sludge at the end of aerobic phase (0.2mg/L) and the second case which waste the sludge at 40 min of settling phase (0.25mg/L). Also, dewatering duration and MC have decreased 1.7% when TS concentration was increased from 0.31% to 0.5% during aerobic condition. Hence, it has concluded the system performance was less influenced by the operation time change of PLC program.

• 디지털산업정보학회논문지
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• 제16권2호
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• pp.69-81
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• 2020

The objective of this study is to seek ways to maximize learning effects from e-learning by drawing improvement directions through investigating and analyzing an awareness of e-learning among e-learning attendees. The study was conducted among the attendees who are taking the e-learning program operated by K University and collected data from the students taking second semester in 2018 with the use of structured questionnaires. For data processing, SPSS Statistics 22.0 and AMOS were used, along with such analytical methods as frequency anslysis, descriptive statistical analysis, ANOVA (Analysis of Variance), t-analysis and cross tabulation. For significant data, it conducted an analysis by carrying out the Scheffe's test. According to the findings from this study, they showed a significant difference only in gender and curriculum desired to be opened in the question about e-learning participation motives per background factor. As for the learners' motives to study, it was confirmed that they tend to become more biased on time utilization and convenience of learning methods. The analysis of which factor of the three - learning factors, system factors and instructor's factors - has greatest effects on learning satisfaction indicated that learning factors influenced learning satisfaction the most in accordance with values for non-standard coefficient beta, followed by instructor factors which had a direct effect.

• 통합자연과학논문집
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• 제11권3호
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• pp.148-153
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• 2018

In this paper, we propose a hybrid-recognition system to obtain the state information and control the Internet of Things (IoT) based smart devices using two recognitions. First, we use a facial recognition for checking the owner of the mobile devices, i.e., smartphones, tablet PCs, and so on, and obtaining the state information of the IoT based smart devices, i.e., smart cars, smart appliance, and so on, and then we use a fingerprint recognition to control them. Further, in the conventional system, the message of the state and control information between the mobile devices and smart devices is only exchanged through the cellar mobile network. Thus, we also propose a direct communication to reduce the total transmission time. In addition, we develop a testbed of the proposed system using smartphones, desktop computers, and Arduino vehicle as one of the smart devices. We evaluate the total transmission time between the conventional and direct communications and show that the direct communication with the proposed system has better performance.

• 산업경영시스템학회지
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• 제44권3호
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• pp.248-261
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• 2021

Scientific and technological performances (e.g., patents and publications) made through R&D play a pivotal role for national economic growth. National governments encourage academia-industry cooperation and thereby pursue continuous development of science technology and innovation. Increasing R&D-related investments and manpower are crucial for national industrial development, but evidence of poor performance in business performance, efficiency, and effectiveness has recently been found in Korea. This study evaluates performance efficiency of the 6T sector (Information Technology, Bio Technology, Nano Technology, Space Technology, Environment Technology, Culture Technology), which is considered a high-potential promising industry for the next generation growth and currently occupies two thirds of the national R&D projects. The study measures the relative efficiency of R&D in a comparative perspective by employing the Data Envelopment Analysis (DEA) method. The result reveals overall low efficiency in basic R&D (0.2112), applied R&D (0.2083), development R&D (0.2638), and others (0.0641), confirming that economic performance and efficiency were relatively poor compared to production efficiency. Efficient R&D needs policy makers to create strategies that can increase overall efficiency by improving productivity performance and quality while increasing economic performance.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 춘계종합학술대회 A
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• pp.689-692
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• 2008

Hierarchical modulation has been considered for achieving higher data rates in Terrestrial-DMB(T-DMB) systems. And for achieving a higher data rates transmission, the low-priority (LP) data, which is used to carry additional data, such as video data, audio data and textual data, should be perfectly decoded in a certain value of $E_b/N_o$. Unfortunately, the man-made noise badly affects the high-priority (HP) symbol, which is used to carry the conventional data in the existed T-DMB system; and since the advanced T-DMB system is proposed to fit for the legacy T-DMB receivers, the low-priority symbols in the hierarchical modulation are much worse affected by the neighbors, who are both in the same quadrant. Because of the feature that mentioned previously, the turbo code has been considered to deal with the LP data. And due to the degradation which caused by the shortened symbol distance, the error performance of LP data is not sufficient by only using the turbo code. In this paper, we propose a Reed-Solomon code used outside of turbo code, and with the turbo code, it becomes a concatenated code. In this paper, there are some simulation results, within the comparison of those performances, we can see how a Reed-Solomon code is utilized for degradation of error performance which is caused by the hierarchical constellation, and how to design a Reed-Solomon code which is suitable for improving the degradation of error performance.

• 한국통신학회논문지
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• 제23권6호
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• pp.1562-1574
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• 1998

본 논문에서는 ATM(Asynchronous Transfer Mode) 교환기 시스템에 T1, E1 및 부분적으로 E1급 속도의 중 저속 HDSL(High-rate digital subscriber line) 정합 기능을 개발하고, 근단누화(NEXT), 임펄스. 선로 잡음(power line noise) 및 접지 임피던스(longitudinal) 잡음 같은 주요 전송 손실이 존재하는 0.4 mm 및 0.5 mm의 기존 전화가입자 선로(UTP, Unshielded twisted pair)를 사용하는 CSA(Carrier serving areas) 선로 모델을 이용하여 $10^{-7}$의 BER(Bit error rates)의 전송 성능을 만족하기 위한 가입자 서비스 전송 거리 성능을 평가하였다. HDSL은 DSI, ISDN 기본 속도 접속 및 DLC 피더에 사용될 것이며 광 케이블과 인터페이스될 것이다. 또한, HDSL 시잔 전망을 제시한다.