• 한국조명전기설비학회지:조명전기설비
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• 제7권3호
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• pp.27-33
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• 1993

본 논문은 캐리어 주파수 20kHz 이상의 고주파 전압형 PWM 인버터를 구동하기 위한 디지털 제어기에 관한 연구이다.적절한 PWM 패턴을 선택하기 위하여 기존의 PWM을 분석하였고, 비동기형 계단 정현파를 기준신호로 하여 제어기의 PWM 패턴을 구하였으며, PWM 제어방법은 가변 캐리어 비를 이용하였다.PWM 제어기는 모두 디지털 방식으로 구성하였다. 특히, 제시된 제어기의 구성은 연산 및 데이터 처리와 PWM 패턴 합성을 8비트 원칩 마이크로프로세서와 디지털 로직으로 나누어 설계하므로써 제어에 대한 속응성 및 제어성을 개선하였다. 또 변조도 데이터를 9비트로 출력하도록 프로그램을 적절히 이용하여 데이터 처리능력을 높였다.디지털 제어기는 회로구성을 i8051과 원칩 EPLD로 구성하였고, 설계된 제어기는 전압형 인버터를 동작시켜 제어성을 고찰하였다. 그리고 전압형 인버터 시스템의 고조파와 전류파형을 평가 분석하였다.

• 대한전기학회논문지:전력기술부문A
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• 제49권10호
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• pp.516-523
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• 2000

In this paper, intelligent methods using digital protective relay in power supervisory control system is developed in order to protect power systems by means of timely fault detection and diagnosis during operation for induction motor which has various load environments and capacities in power systems. The spectrum pattern of input currents was used to monitor to state of induction motors, and by clustering the spectrum pattern of input currents, the newly occurrence of spectrums pattern caused by faults were detected. For diagnosis of the fault detected, the fuzzy fault tree was derived, and the fuzzy relation equation representing the relation between an induction motor fault and each fault type, was solved. The solution of the fuzzy relation equation shows the possibility of each fault's occurring. The results obtained are summarized as follows: 1) The test result on the basis of KEMC1120 and IEC60255, show that the operation time error of the digital motor protective relay is improved within ${\pm}5%$. 2) Using clustering algorithm by unsupervisory learning, an on-line fault detection method, not affected by the characteristics of loads and rates, was implemented, and the degree of dependency by experts during fault detection was reduced. 3) With the fuzzy fault tree, fault diagnosis process became systematic and expandable to the whole system, and the diagnosis for sub-systems can be made as an object-oriented module.

• Smart Structures and Systems
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• 제12권3_4호
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• pp.363-379
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• 2013

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.

• 한국의류학회지
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• 제40권6호
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• pp.1025-1033
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• 2016

It is important to compare and analyze digital camouflage from different countries to promote the continuous development of a camouflage combat uniform. This effort should lead to developing a camouflage pattern suitable for the domestic environment and expand its performance of night camouflage. This study investigates digital camouflage by comparing camouflage fabrics sampled from Korea and eight other countries (USA, UK, Singapore, Croatia, Colombia, and Mongolia) in terms of textile, near-infrared reflectivity of colors, and color distribution. First, the fabric construction of camouflage from Korea, UK, US, Singapore, Span, and Croatia were all characterized by derivative plain weaves, while derivative twill weaves were generally used in Croatia and Mongolia. It is assumed that derivative plain weaves are adopted to improve the tearing strength of fine yarns. However, twill weaves enhance the flexibility of coarse yarn fabrics. Next, reflectivity change was analyzed based on camouflage color. The reflectivity of a combat uniform in Korea, Colombia, Croatia, and UK increased before 780nm in the visible light range, but remained consistent from 800nm which falls under the near-infrared range. In contrast, camouflage samples in Mongolia, Span, Singapore and USA showed a gradual increase of reflectivity in the near-infrared range. Finally, the color distribution analysis of digital camouflage found that camouflage of countries with desert or woodland combat settings dominantly contained brown colors. It indicates the color pattern consideration of different geographic regions is important to determine camouflage performance. This research involves basic study that will have implications for developing patterns and colors suitable for the South Korean environment and expand its use as night camouflage that helps achieve continuous improved camouflage performance.

• 한국실내디자인학회논문집
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• 제14권4호
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• pp.19-26
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• 2005

Digital technology continually makes a space evolves. The real-time behavior design communicates the data with the situation of circumference of the space(visitors moving, interior and exterior situations). The space form was changed because it interfaces in real time. The purpose of this study was finding out the characteristics of real-time behavior space design through the analysis of space formative languages, sensorium, S-R and material. This study will be the one of basic references for the digital space design. The boundary of this study set limits to the works of digital space designer who applies the real-time exchanging data to their design among the digital space design works from 1996 to 2004. But it excepted from the real-time behavior space in virtual realty. Therefore, the objects of this study were the works of onl and NOX(paraSITE, Trans-port 2001, Muscle, MotormeCCa, Handdrawspace, Saltwater Pavilion, Son-O-House, H2O Expo). The method was the contents analysis of space formative languages(Greg Lynn's ten space formative languages; bleb, blob, branch, flower, fold, lattice, teeth, shred, skins and strand), sensorium, S-R and material. The results of the study are as follows: 1) The organizational elements; Space formative languages(bleb, blob, fold, shred, skins, strand), stimulation(Human Participation, Human Moving, Weather Conditions), and response(Spatial Moving, Sound Pattern, Lighting Pattern, color Pattern, Activating Particles, Moving Picture, Virtual Friend) 2) The material Use; Sound, lights, and network have been used in the space. Immaterial matter will be used the main material of space design in 21"'century, 3)The spatial types; formal changing of space, projecting immaterial elements, and changing the sound.

• ETRI Journal
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• 제26권1호
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• pp.53-56
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• 2004

In this letter, we propose a novel design scheme for an optimal non-uniform planar array geometry in view of maximum side-lobe reduction. This is implemented by a thinned array using a genetic algorithm. We show that the proposed method can maintain a low side-lobe level without pattern distortion during beam steering.

• ETRI Journal
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• 제25권3호
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• pp.187-194
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• 2003

Delay testing has become an area of focus in the field of digital circuits as the speed and density of circuits have greatly improved. This paper proposes a new scan flip-flop and test algorithm to overcome some of the problems in delay testing. In the proposed test algorithm, the second test pattern is generated by scan justification, and the first test pattern is processed by functional justification. In the conventional functional justification, it is hard to generate the proper second test pattern because it uses a combinational circuit for the pattern. The proposed scan justification has the advantage of easily generating the second test pattern by direct justification from the scan. To implement our scheme, we devised a new scan in which the slave latch is bypassed by an additional latch to allow the slave to hold its state while a new pattern is scanned in. Experimental results on ISCAS'89 benchmark circuits show that the number of testable paths can be increased by about 45 % over the conventional functional justification.

• 전기학회논문지P
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• 제65권3호
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• pp.224-234
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• 2016

This study developed the conductivity pattern of solid surface using laser direct pattern and compound polymer material technology. For development direct patterning system of solid surface, we used the laser power stabilizer, the dynamic focusing, 3D scanner S/W and the auto aligning techniques. Also For conductivity pattern, we are developed compound polymer material with additive by electro-less plating. These technologies are already used commercially. However operation and control integrated system for direct patterning of solid surface are not yet developed. The objective of this paper is to introduce the laser direct structuring for simple process improvement instead complex PCB process, and develop the operating stability and integration system. Also we implemented new application of laser direct structuring through sample manufacture.

• Safety and Health at Work
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• 제10권1호
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• pp.67-74
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• 2019

Background: Few studies have examined the effects of a forward rotating shift pattern on police employee performance and well-being. This study sought to compare sleep duration, cognitive performance, and vigilance at the start and end of each shift within a three-shift, forward rotating shift pattern, common in United Kingdom police forces. Methods: Twenty-three police employee participants were recruited from North Yorkshire Police (mean age, 43 years). The participants were all working the same, 10-day, forward rotating shift pattern. No other exclusion criteria were stipulated. Sleep data were gathered using both actigraphy and self-reported methods; cognitive performance and vigilance were assessed using a customized test battery, comprising five tests: motor praxis task, visual object learning task, NBACK, digital symbol substitution task, and psychomotor vigilance test. Statistical comparisons were conducted, taking into account the shift type, shift number, and the start and end of each shift worked. Results: Sleep duration was found to be significantly reduced after night shifts. Results showed a significant main effect of shift type in the visual object learning task and NBACK task and also a significant main effect of start/end in the digital symbol substitution task, along with a number of significant interactions. Conclusion: The results of the tests indicated that learning and practice effects may have an effect on results of some of the tests. However, it is also possible that due to the fast rotating nature of the shift pattern, participants did not adjust to any particular shift; hence, their performance in the cognitive and vigilance tests did not suffer significantly as a result of this particular shift pattern.

• 동의신경정신과학회지
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• 제34권3호
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• pp.141-150
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• 2023

Objectives: This study aimed to comprehend the characteristics of Korean medicine patterns in relation to varying degrees of cognitive impairment in an elderly population. Methods: The dataset included 127 elderly individuals with cognitive impairment obtained from three Korean medicine hospitals between 2018 and 2021. The participants were categorized into two groups based on Clinical Dementia Rating-Sum of Boxes (CDR-SB) scores: those with questionable impairment (QI) and those with very mild dementia (VMD). A diagnostic framework for Korean medicine patterns encompassing Qi deficiency, Yin deficiency, Phlegm dampness, and Heat-fire was employed. Liver blood markers, including aspartate aminotransferase (AST), alanine aminotransferase (ALT), and the AST/ALT ratio, were also analyzed. Results: The scores of the cognitive assessment tools (MoCA-K, MMSE-DS, and K-IADL) of the QI group significantly differed from those of the VMD group. CDR-SB exhibited a positive correlation with the scores of each pattern of Qi deficiency, Yin deficiency, Phlegm dampness, and Heat-fire, whereas ALT and AST values displayed negative correlations. Binomial logistic analysis, controlling for potential confounders, such as age, education years, body mass index, the presence of chronic disease, and the presence of medication, verified that the VMD group showed higher pattern scores and lower ALT and AST values than the QI group. Conclusions: Increases in pattern scores along with decreased AST and ALT levels might be indicative of more severe cognitive impairment.