• Journal of Korean Ophthalmic Optics Society
• /
• v.3 no.1
• /
• pp.87-92
• /
• 1998

Unaided visual acuity was tested by ACP-7 TOPCON chart projector on 376 kindergarteners and objective refraction error was measured by NIDEK ARK-700A auto-refractokeratometer on 554 eyes aged 3 to 5. The results were as follows ; The average unaided visual acuity of children aged 3 was 0.82, aged 4 was 0.90 and aged 5 was 0.92 respectively theerfore children s visual acuity has been gradually developed with their age. The kind of refractive error was 1% for hyperopia, 14% for hyperopic astigmatism, 3% for myopia, 50% for myopic astigmatism, 18% for mixed astigmatism and 14% for emmetropia respectively.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.8
• /
• pp.1415-1423
• /
• 2007

Total efficiency of transmitter system was improved by developing combinational 2-Way Isohybrid for GSM1900 base station in this paper. The size of product was decreased and the characteristics were stabilized. The isohybrid transmitter combiner of chip coupler type and hybrid coupler type were designed and fabricated. Insertion loss for chip coupler type isohybrid was $3.17\;dB{\sim}3.47\;dB$. On the other hand, insertion loss for hybrid coupler type was $3.17\;dB{\sim}3.42\;dB$. Isolations between ANT and port were $24.23\;dB{\sim}29.98\;dB$ in case of chip coupler type Isohybrid and were $26.28\;dB{\sim}36.91\;dB$ in case of hybrid coupler type, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.125-128
• /
• 2013

The reason why visual fatigue occurs while watching 3D TV is because the left/right images of the fixed disparity are played. This paper proposes a measuring method of pupil distance and the 3D location of a viewer using stereo camera modules, and a reflection method of the data into 3D TV.

• Korean Journal of Ecology and Environment
• /
• v.47 no.3
• /
• pp.232-238
• /
• 2014

We have developed a non-destructive, touch-free method for estimating leaf areas with a structured-light three-dimensional (3D) scanner. When the surfaces of soybean leaves were analyzed with both the 3D scanner and a leaf area meter, the results were linearly related ($R^2=0.90$). The strong correlation ($R^2=0.98$) was calculated between shoot fresh weights and leaf areas when the scanner was employed during growth stages V1 to V4. We also found that leaf areas measured by the scanner could be used to detect changes in growth responses to abiotic stress. Whereas under control conditions the areas increased over time, salt and drought treatments were associated with reductions in those values after 14 d and 12 d, respectively. Based on our findings, we propose that a structured-light 3D scanner can be used to obtain reliable estimates of leaf area and plant biomass.

• Proceedings of the KSME Conference
• /
• 2005.11a
• /
• pp.50.1-50.1
• /
• 2005

• Proceedings of the Korean Society of Medical Physics Conference
• /
• 2003.09a
• /
• pp.50-50
• /
• 2003

World Wide Web (WWW)에서 Virtual Reality Modeling Language (VRML)를 이용하는 3 차원 (3D) 디스플레이는 사용자에게 직관적인 정보를 더 효과적으로 제공해 준다. 웹을 기반으로 하는 해부학적 영상과 융합되는 기능적 영상의 3D 가시화는 아직까지 체계적인 방식으로 연구가 활발히 진행되지 않았다. 이 연구의 목적은 2D 영상들과 함께 웹에서 VRML을 이용하여 구현되는 3D 해부학적 표면 영상들과 기능적 표면 영상들을 동시적으로 관찰할 수 있게 하고 VRML을 통해 만들어진 거리 측정 도구를 가지고 관심영역의 공간적인 위치 정보를 제공하는 것이다. 본 연구에서는 한 명의 간질 환자로부터 Magnetic Resonance (MR) 축면 영상과 발작기 및 발작간기 Single Photon Emission Computed Tomo graphy (SPECT) 축면 영상들을 각각 획득하였다. 발작 진원지의 확인을 향상시키기 위해서 subtraction ictal SPECT co registered to MRI (SISCOM) 을 수행하였다. SISCOM 결과로 나타난 각 2D 영상들은 모든 voxel 들의 평균 값 위로 1 표준편차와 2 표준편차에 해당하는 문턱 이상의 영상 값을 갖도록 하였다. SISCOM으로 나타나는 간질 발작 진원지들과 MRI 영상에서 회색질, 백색질 및 뇌척수액의 경계들을 각각 분할하고 marching cube 알고리즘에 의해 VRML 표면 영상들로 나타내었다. 축면 영상에서 실제 거리를 나타내는 x, y 축의 길이를 측정하고 z 축선의 길이를 계산하였다. VRML을 이용한 거리 측정 도구를 만들어 이전의 VRML 표면 영상들과 융합하였다. MRI 영상을 이용하여 3D 표면 영상들의 단면을 나타내고 3D 표면 영상들의 투명도를 설정하기 위해 Java Script 루틴을 사용자 인터페이스 도구로서 삽입하였다. 웹 페이지에서 구현되는 3D 표면 영상들의 투명도와 관찰 위치를 조절함에 따라 모델들 사이의 공간적인 정보를 직관적으로 알 수 있었다. 간질 발작 진원지에 대응하는 해부학적 구조를 3D 표면 영상들을 가로지르는 MRI 평면 영상들을 통해서 확인하였다. 결론적으로 본 연구에서 제시하는 웹에 근거한 3D 융합 영상의 가시화와 위치 측정은 진단 및 치료 방사선학과 외과학 등의 분야에서 온라인 방식의 연구와 교육에 있어 많은 도움을 줄 것이다.

• Journal of KIISE:Computing Practices and Letters
• /
• v.15 no.6
• /
• pp.454-458
• /
• 2009

The technology of virtual environments has been developed with better-quality appearance on a computer display in mind, but without consideration for objects' precise measurements in physical units. With the increased application of computer graphics in a variety of areas, there is a need for precise measurement functionality in addition to visualization. This paper describes the definition of physical properties using measurement units for X3D based virtual objects, to provide their precise physical information in virtual environments. To this end, we have included the physical property node in the X3D specification. The physical measurement units, such as length, mass, time, temperature, etc., are based on SI units (International System of Units).

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.163-166
• /
• 1998

Toen 방식을 사용하는 거리 측정시스템의 잡음 및 간섭에 대한 열화 도를 분석한다. 위성 링크상의 잡음 및 다중 변조 방식에 의한 전송 신호간 간섭들로 인하여 위상차 측정에 열호가 발생하며, 열화 도는 ranging 측정 시스템의 잡음 대역폭에 의존한다. Ranging 측정 모드에서는 잡음 대역폭 8Hz, 4Hz 그리고 1Hz에 대하여 0.3dB 열화가 방샐하였으며, ranging 및 원격 측정 데이터 전송 모드에서는 대역폭에 따라 6.4dB, 4.2dB, 4dB가 발생하였다.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.10
• /
• pp.949-957
• /
• 2017

A laser-vision-based height measurement system is developed and implemented for the inspection of two-step variable valve lift module assemblies. The proposed laser-vision sensor module is designed based on the principle of laser triangulation. This paper summarizes the work on 3D point cloud data collection and height difference measurements. The configuration of the measurement system and the proposed height measurement algorithm are described and analyzed in detail. Additional measurement experiments on the height differences of valves and lash adjusters of a two-step variable valve lift module were implemented repeatedly to evaluate the accuracy and repeatability of the proposed measurement system. Experimental results show that the proposed laser-vision-based height measurement system achieves high accuracy, repeatability, and stabilization for the inspection of two-step variable valve lift module assemblies.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.9
• /
• pp.3406-3411
• /
• 2010

Assessment of the accommodative response is an essential part of the optometric examination. This study measured objectively the accommodation responses those were measured by Autorefractor, MEM retinoscopy and Nott dynamic retinoscopy, and investigate the correlation and difference the results. Twenty-seven college students with normal visual acuity aged 19 to 29 years (mean $22.7{\pm}2.43$ years) participated in this study. Their accommodative responses to accommodative demand of 4D (25cm) were measured with Shin-Nippon NVision-K 5001 Autorefractor, MEM retinoscopy and Nott dynamic retinoscopy. The accommodative responses to accommodative demand of 4D were $3.70{\pm}0.25D$ by Shin-Nippon NVision-K 5001 Autorefractor, $3.58{\pm}0.30D$ by MEM retinoscopy and $3.77{\pm}0.29D$ by Nott dynamic retinoscopy, respectively. There were high correlations among the three techniques (p<0.05). MEM retinoscopy was measured $0.19{\pm}0.13D$ lower than Nott dynamic retinoscopy (p<0.05) and it was measured $0.12{\pm}0.24D$ lower than Shin-Nippon NVision-K 5001 Autorefractor (p<0.05). There was no significant difference between Nott dynamic retinoscopy and Shin-Nippon NVision-K 5001 Autorefractor (p>0.05). MEM retinoscopy showed lesser accommodative responses than Nott dynamic retinoscopy and Shin-Nippon NVision-K 5001 Autorefractor. Author suggest that Nott dynamic retinoscopy may use Shin-Nippon NVision-K 5001 Autorefractor interchangeably to evaluate accommodative responses expect MEM retinoscopy.