• Journal of Korean Ophthalmic Optics Society
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• v.20 no.2
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• pp.133-140
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• 2015

Purpose: It was investigated whether two different stabilization designs of toric contact lenses changed the rotational axis and degree of toric lenses according to body posture and gaze direction in the present study. Methods: Toric soft contact lenses with Lo-Torque$^{TM}$ design and ASD design (accelerated stabilized design) were fitted on 52 eyes aged in 20s-30s. Then, rotational degree was measured at the five gaze directions including front gaze and the lying position. Results: When gazing the front and vertical directions in the upright posture, lens was much rotated to nasal side for the Lo-Torque$^{TM}$ design and temporal side for the ASD design. When gazing horizontal direction, both design lenses were rotated against to the gaze direction. Rotation degree was the smallest at superior direction gaze and the largest at nasal gaze. In case of the rotation degree less than $5^{\circ}$, Lo-Torque$^{TM}$ design was more frequent when gazing front and vertical directions, and ASD design was more frequent when gazing horizontal direction. In addition, the lens with Lo-Torque$^{TM}$ design was lesser rotation degree than with ASD design immediately after lying. On the other hand, the lens with ASD design was lesser rotation degree than with Lo-Torque$^{TM}$ design 1 minute later after lying. Conclusions: This study confirmed that axis rotation of the lens induced by gaze direction and posture was different according to axis stabilization design during wearing toric soft contact lens.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.143-150
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• 2011

Roundabouts, which belong to traffic circles, are intersections which are similar to the existing rotary form. Roundabouts recently have been constructed all around the world. And interests in roundabouts are increasing in Korea. However, there are lacks of research on pedestrian volume which has a great influence on operation efficiency of roundabouts in urban area. Therefore, this study suggests efficiency analysis and pedestrian signals in roundabouts according to the pedestrian volume. First, VISSIM simulation was organized to analyse volume of one lane roundabouts in urban area. Second, average delay of intersections was calibrated by VISSIM simulation dividing signalized intersections and non-signalized intersections depending on pedestrian volume. Finally, this study showed that roundabouts are suitable when pedestrian volume was under 200person/hr and traffic circles with a pelican signal are suitable when pedestrian volume was over 200person/hr. And when pedestrian volume and traffic volume are over 600person/hr and 1,500vph respectively, fixed signalized intersections fit well.

• Journal of Korean Society of Transportation
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• v.34 no.5
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• pp.449-464
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• 2016

The purpose of this study is to test applicability of cut-through roundabouts at a congested intersection and to provide the traffic volume ranges for theirs application. Various test scenarios were developed according to variation of total traffic volume, left-turn ratio to total traffic volume, and ratio of major road traffic volume to minor road traffic volume. In addition, three intersection types of cut-through roundabout, roundabout, and signalized intersection were compared with respect to delay times for each scenario, resulted from the simulation using VISSIM. In case of the ratio of major road traffic volume to minor road traffic volume, 6:4, the delay times of cut-through roundabout decreased up to 30% of left-turn ratio to total traffic volume for 400vphpl, up to 20% for 500vphpl, up to 10% for 600vphpl. In case of the ratio, 7:3, they are the same as 6:4 for 400vphpl, 500vphpl, and 600vphpl but they decreased up to 30% for 300vphpl and up to 10% for 700vphpl. In case of the ratio, 8:2, they are the same as 7:3 for 400vphpl, 500vphpl, and 700vphpl but they were reduced by 10% to 30% for 300vphpl and 20% for 600vphpl. It is concluded that the smaller left-turn ratio to total traffic volume as well as the ratio of minor road traffic volume to major road traffic volume is, the more effective in reducing delay times the cut-through roundabout is. Cut-through roundabouts can be expected to reduce delay times at a signalized intersections with traffic conditions above-mentioned.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.4
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• pp.54-67
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• 2016

All roundabouts are designed based on "Roundabout Design Guideline, Ministry of Land and Transportation, 2014" in Korea. The guideline also provides the traffic volume criteria to convert from signalized intersections to roundabouts. While the criteria are based on capacity of roundabouts, left-turn ratio and the number of lane on approaches are not considered to calculate the capacity of roundabouts. Therefore it is difficult to apply the traffic volume criteria in the real world. In this study, we studied the impact of left-turn ratio and the number of lane on approaches into capacity of roundabouts using micro-simulation. It was found that the capacity of roundabouts is changed according to left-turn ratio and the number of lane on approaches.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.2
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• pp.189-198
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• 2014

Purpose: The present has analyzed the correlation between the direction of lens and the amount of rotation upon soft toric contact lens fitting after classifying the corneal astigmatism. Methods: Soft toric contact lens was fitted on 114 with-the-rule astigmatic eyes with total astigmatism of at least -0.75 D in their 20s and 30s according to the fitting guideline of the manufacturer and the correlation between the astigmatic degree and the rotational direction/amount of rotation was analyzed by when keeping the eyes on the front and by changing the direction of gaze. As for re-orientation movement. The speed of lens re-orientation and total amount of lens rotation was compared and analyzed by corneal astigmatism after mis-location of lens of $45^{\circ}$ to temporal and nasal direction, respectively. Results: The positive correlations were shown between corneal astigmatism and the direction of lens rotation and between corneal astigmatism and the amount of lens rotation. Meanwhile, the amount of lens rotation was different by the direction of gaze however, there was no correlation with corneal astigmatism. The speed of lens re-orientation was fastest in the group of high astigmatic degree when the lens was mis-located to both temporal and nasal directions. Conclusions: For optimal axis stabilization of toric soft lens, it is proposed that the adjustment of fitting guideline considering corneal astigmatism is necessary since the current fitting guideline is only based on total astigmatism.

• Journal of Korean Ophthalmic Optics Society
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• v.10 no.4
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• pp.255-259
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• 2005

When we wear contact lenses for correcting astigmatism, we often experience the axis-rotation of contact lenses that is happened in case we could not fit the axis of lens exactly or by the eyelid used to blink. In this case, because the exact correcting state becomes in the wrongly correcting state, the asthenopia is led, and the decline of eyesight can be led. For this reason, we need to know axis-rotating degrees of contact lenses. If a contact lens rotated, a residual astigmatism may be detected in the refraction examination after wearing. Using this, we developed a program that calculates the axis-rotating amount of contact lenses.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2485-2488
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• 2003

본 논문에서는 DSP를 이용하여 운동하는 물체의 회전량을 측정하는 실린더형 진동 자이로스코프(이하 자이로) 제어기를 개발하였다. 진동 자이로를 구동하기 위해서는 정밀 진동제어와 신호 처리와 같은 고급 제어 기술이 필요하다. 정밀진동제어는 진동 자이로를 구동하기 위해 필요한 핵심기술로써 기존의 PLL(phase-locked loop)방식은 외부환경에 민감하여 구현이 까다로울 뿐만 아니라 자이로 개개의 고유 진동수가 다르기 때문에 대량 생산에 어려움이 있었다. 또한 자이로 출력 신호로부터 회전량을 검출하기 위해서는 진폭과 당향성 검출의 본 회로뿐만 아니라 잡음 제거와 신호 증폭, 온도 보상과 같은 전처리 과정도 필요하다. 본 논문에서는 DSP를 통해 정밀 진동제어와 잡음 제거, 방향성 검출 등의 기능들을 구현하였으며 증폭과 진폭(회전량) 검출은 아날로그 회로를 이용하였다. 또 한 외부와의 인터페이스를 위해 D/A 회로를 설계하였고 이들을 실험을 통해 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.417-420
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• 2010

반도체 패키지 제조공정 중에는 제품에 일련번호를 인쇄하는 마킹공정이 있다. 마킹 공정에서 새겨진 문자는 해당 관리기준에 따라 관리되고 있는데 최근 반도체 패키지의 소형화에 따라 인쇄된 마크문자의 틀어짐 정도가 관리기준에 미달되는 문제가 발생되고 있다. 본 논문에서는 마크문자의 검사 항목 중 tilted mark(angle mark) 검사를 위한 회전량 측정방법으로 golden section searching 방법을 적용한 고속 라돈 변환(radon transform)방법을 제안한다. 실험에서는 제안한 방법이 일반적인 라돈 변환에 비해 최대 약 21 배의 회전량 측정속도가 향상되는 것을 확인하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.6
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• pp.707-714
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• 2021

An important factor that causes delays at roundabouts is unbalanced traffic conditions. The majority of domestic studies have tendedto focus on the proportion of entering traffic rather than conflicting traffic in order to explain unbalanced traffic conditions. Also, there is scant research on the proper distance between a signalized intersection and a roundabout. In this study, therefore, unbalanced traffic conditions and optimal distance between two intersections were analyzed using SIDRA software based on the Gajwa-ro roundabout in Icheon, where unbalanced traffic conditions occur during afternoon peak hours, and its position is 295 m from a signalized intersection. It was found that a state of unbalanced traffic conditions in the form of conflicting traffic caused delays at Gajwa-ro roundabout, and the queuing length on each approach was removed when there was 850 m of distance between two intersections.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.869-875
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• 2019

The service level of the roundabout is estimated through an analytic model using the geometrical characteristics and parameter values obtained from the observations. Although a lot of researches have been conducted on the rotational intersection through an analytical model, the case of variable combinations is enormous, suggesting the range and service level of appropriate traffic volume according to the case study or limited characteristics through simulation. Therefore, in this study, the roundabout analysis model was constructed by using Visual Basic Application to make variable adjustment more easily. The constructed model analyzes traffic conditions according to various situations and analyzes the characteristics of roundabouts. As the result of analysis, the more the ratio of left turn and U-turn, the more the traffic distribution of each approached road was biased to one side, the limit traffic volume of the roundabout decreased and congestion appeared quickly. In particular, the more uneven the distribution of traffic was, the less the Saturation traffic volume was affected by the turnover rate.