• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.7B
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• pp.884-890
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• 2001

본 논문에서는 장거리 광 전송로에 대한 시뮬레이션을 효과적으로 빨리 할 수 있는 전파 매개변수 매핑 방법을 제안한다. 이 방법은 많은 광섬유 섹션들과 증폭기들로 구성된 긴 전송로를, 매핑된 전파 매개변수를 갖는 단 하나의 광섬유 섹션의 전송로로 모델링 하는 것이다. 그리고, 본래의 전송로 대신 모델링된 전송로를 사용하여 시뮬레이션을 하고 성능을 분석한다. 그것의 성능을 eye diagram, 정상 시뮬레이션과 제안된 매핑 방법에 의한 eye-opening 들의 차이, 시뮬레이션 시간의 감소 정도를 통해 확인한다. 시뮬레이션 결과에서 이 방법은 정상 시뮬레이션과 비교할 때 3% 이내의 eye-opening 차이를 가질 만큼 광 신호의 전파특성을 정확하게 서술하고 시뮬레이션 시간은 광섬유 섹션의 수가 20일 때 정상 시뮬레이션의 34.72%로 감소시켜 주는 것을 확인하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.1-6
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• 2009

This paper presents new high speed architecture using DBI(Data Bus Inversion) in DRAM. The DBI is one of the general methods in the signaling circuits to decrease the known problems such as SSO and LSI. Many architectures have been proposed to reduce the number of transitions on the data bus. In this paper, the DBI, the Analog Majority Voter (AMV) circuit, the GIO control circuit and the SSO algorithm are newly proposed. The power consumption can he reduced with the help of direct GIO inversion method and the eye diagram of data can be increased to 40ps. Using proposed DBI scheme can produce almost stable SI of DQs against high speed operation. The DBI is fabricated in 90nm CMOS Technology.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.79-86
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• 1999

A simulation of 10 Gbps optical fiber transmission system using DCf(dispersion compensating fiber) for the dispersion compensation is performed. In order to analyze the NRZ pulse propagation in nonlinear, dispersive and lossy fiber, the split-step finite element method that is combination of finite element method and finite difference method is used. Also, we obtained the optical eye diagram and BER characteristics at the receiver of the system that is contained the optical amplifier and system noises. As a result of simulation, we obtain that the dispersion penalty is about 0.8dB after 50km transmission and the receiver sensitivities at $10^{-9}$ BER are -27.4dBm with EDFA pre-amplifier of 12dB gain and -15.6dBm without EDFA.

• Journal of the Ergonomics Society of Korea
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• v.36 no.4
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• pp.343-353
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• 2017

Objective: This study aims to evaluate the efficiency of two representative subway map design types, namely a diagram type and a geographical type using physiological metrics, performance metrics, and self-reported metrics, which are representative usability metrics. Background: Subway maps need to be designed in order for users to quickly search and recognize subway line information. Although most cities' subway maps currently use the diagram type designed by Henry Beck, New York City's subway map has recently been changed to the subway map type combined with the geographical type designed by Michael Hertz. However, not many studies on its efficiency are found, and the studies that are available mainly depend on questionnaire surveys or take on a subjective behavioral study type based on experts' experiences. In this regard, evaluation through a more objective method is needed. Method: This study employed usability metrics as a method to evaluate the efficiency of information search targeting the diagram type and geographical type subway maps used mostly as subway maps. To this end, physiological metrics obtained through eye tracking, task completion time, representative metric of task performance, and subjective evaluation metrics were used for the suitability evaluation of subway map designs. Results: In the result of gaze movement distance analysis, no significant difference was shown in the two design types in terms of a process finding a departure station from the starting point and a process finding a transfer station between the departure station and arrival station (destination). However, the gaze movement distance in the process finding the arrival station at the departure station was significantly shorter in the geographical type, rather than in the diagram type. The analysis of task completion time showed a result similar to the gaze movement distance analysis result. Task completion time was significantly shorter in the geographical type, rather than in the diagram type, which is in the process finding the arrival station at the departure station. In other information search processes, no significant difference was shown. As a result of subjective evaluation metrics analysis, no significant difference was revealed in the two design types. Conclusion: An analysis on the two representative subway map design types was carried out via the adoption of usability metrics. As a result, although no significant difference was shown in some information search processes, it was revealed that information search was easier in the geographical type overall. Also, it was found that usability metrics can be effectively used to evaluate the design types of subway maps. Application: The study results can be used to set design direction to offer ease in information search on subway lines. The study also can be used as a method to evaluate a subway map's design type.

• Journal of Korean Elementary Science Education
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• v.32 no.4
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• pp.527-534
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• 2013

This study investigated elementary school teachers' understanding of the image formation by converging lens, pinholes camera, mirror and water. In each case teachers were asked to draw the ray diagram to indicate the position of the image. Teachers' ray diagrams were analyzed in accordance with the scientific process of image formation. Results of analysis showed that teacher's conceptions were classified into five levels for each situation. And most of the teachers were in level 3 and level 4 in each case. Because they had difficulties in the appling scientific conception(propagating path of light, diffused reflection from each object point, role of the eye, ray tracing) to finding location of image. Also most of teachers didn't know how to apply the law of reflection and refraction to each situation. The study finally discussed the teacher training program of the optical image.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.43-53
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• 2007

We have analyzed low current operation characteristics of a VCSEL transmitter operating at fixed Current over wide temperature range. Used 850 nm oxide VCSEL has low temperature dependence of the threshold current and $d^2I_{th}/dT^2$ is approximately $1.346\times10^{-4}mA/^{\circ}C^2$. We fixed on-current so that output power from the chip is 1 mW at $20^{\circ}C$ and investigated the turn-on, turn-off characteristics and eye-diagram of the 850 nm oxide VCSEL transmitter with varying ambient temperature and off-current. We measured rise time, fall time, extinction ratio and timing jitter by changing tile ambient temperature and off-current. With the fixed off-current of around $0.1\sim0.2mA$ lower than the lowest threshold current the transmitter successfully operated at 1.25 Gbps over a wide temperature range from $-20^{\circ}C$ to $80^{\circ}C$.

• Journal of the Ergonomics Society of Korea
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• v.33 no.3
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• pp.191-202
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• 2014

Objective: This study is conducted on the differences between flat and curved displays with respect to location of focused points, posture and satisfaction as well as preferred tilt angles. Background: In order to avoid physical and eye fatigue caused by misplayed sitting posture, many studies have asserted that the display requires appropriate location, size and tilt angle as well as curvature. However, most studies have focused on the work environment and the results are varied in the extent. Method: Eye height data in sitting posture were collected from 30 participants. Participants selected the most comfortable viewing angle within the range from $0^{\circ}$ to $12^{\circ}$ while watching videos for both curved and flat display. Then, physical and eye fatigue and overall satisfaction were subjectively evaluated. Lateral diagram describing viewing display condition was set and used to develop linear models for expecting the preferred tilt angle. Results: Due to sitting in the natural viewing posture rather than upright, the eye height is lowered to about 4.6 centimeters, on average, for both displays showing no significant differences. In contrast, preferred angles for the two displays are significantly different and this can be interpreted that curvature vary the points focused. Two linear models as functions of sitting eye height are developed to expect preferred tilt angle for each display. Based on the result of overall satisfaction evaluation, curved display is statistically better than flat display. Conclusion: The results show that flat and curved displays are significantly different expect for the viewing posture. However, reasons for preferring curved display are not accurately factorized and the linear models are limited in the experiment condition such as size of display, distance between display and viewer and other physical environmental factors. Further studies on curved displays under more various conditions are required. Application: This study can contribute to use of the curved display in various way.

• Electronics and Telecommunications Trends
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• v.22 no.4 s.106
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• pp.133-143
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• 2007

PCI Express는 고속 차동신호를 사용한 점대점(point-to-point) 프로토콜로 신호무결성(signal-integrity) 측정을 위해 기존의 병렬버스신호와 다른 파라미터(parameter)들이 사용되고 있다. PCI Express 시스템에서 중요한 전기 파라미터는 loss와 jitter이며 eye diagram을 통해서 분석이 가능하다. 본 고는 PCI Express 송수신 버퍼의 전기 규격과 애드인카드(add-in card) 시스템의 전기적 여유(budgets)의 의미와 분석을 다룬다. 또한 실제적인 PCI Express 시스템에서 전기 파라미터들을 측정하고 분석, 디버깅의 방법을 다룬다.

• Electronics and Telecommunications Trends
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• v.20 no.3 s.93
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• pp.112-121
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• 2005

고속직렬프로토콜의 출현으로 기존의 병렬 인터페이스에서 중요하게 사용되던 파라미터들의 의미가 변화되고 있다. 특히 ‘1’, ‘0’의 디지털 신호가 고속의 차동신호로 전송되면서 신호 무결성의 파라미터로 지터(jitter)가 중요한 의미를 가지게 되었다. 본 고는 지터의 발생과 분석, 테스트 등 전분야를 다루고 있다. 지터를 분석하기 위한 방법으로 Eye Diagram, Bathtub 곡선, TIE 히스토그램 등을 다루며 이러한 방법을 사용하여 지터를 각각의 특성별로 분리한다. 그리고 지터를 테스트 장비와 각각의 특징을 살펴본 후 PCI Express 트랜시버 지터 테스트의 실례를 통하여 지터 테스트 방법과 분석을 보여준다.

• Journal of Physiology & Pathology in Korean Medicine
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• v.20 no.6
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• pp.1447-1450
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• 2006

To study on the assignment of the eight trigrams (八卦) in human body being based on based the number of HADO(河圖)-NAGSEO(洛書). Being based on the number of HADO(河圖)-NAGSEO(洛書) and the BEOK-HEE's diagram of eight trigrams order(伏羲次序圖), human being organ (five-Jang organs (liver, heart, spleen, lung and kidney), five organs (ear, eye, mouth and nose), provisional namely six entera for the process on intake, digestion, excretion of food (mouth, stomach, small intestine, large intestine, rectum, anus) are assigned eight trigrams (八卦). Eight trigrams(八卦) are attached to the based on the number HADO(河圖)-NAGSEO(洛書): 1-GEON(乾), 2-TAE(兌), 3-LEE(離), 4-JIN(震), 9-SON(巽), 6-GAM(坎), 7-GAN(艮), 8-GON(坤). And (八卦) are attached to the human being organs (five-Jang organs (live, heart, spleen, lung and kidney), five organs (ear, eye, mouth, nose, anus) : 1-GEON(乾)-left lung-left nose, 6-GAM(坎)-right kidney-right ear, 7-GAN(艮)-left heart-anus, 8-GON(坤)-right liver-right ear. Eight trigrams(八卦) are attached to the provisional namely six entera for the process on intake, digestion, excretion of food : the air(GEON 乾), the month(TAE 兌), the stomach(LEE 離), the small intestine(JIN 震), the large intestine(Son 巽), the rectum(GAM 坎), the anus(GAN 艮), the excrements(GON 坤). The BEOK-HEE's diagram of eight trigrams order(伏羲次序圖) means immutable order naturally. The process of the human being organs( five-Jang organs, five organs and six entera's digestion) is also unchangeable in region and program. Therefore we can set up the five-Jang organs, five organs and the process of six entera's digestion as the category of observation on the basis of BEOK-HEE's diagram of eight trigrams order(伏羲次序圖), and then we can arrange eight trigrams (八卦) on the five-Jang organs, five organs and the process of six entera's digestion.