• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.190-194
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• 2009

Generalized lymphangiomatosis is a rare congenital malformation of the lymphatics. CT and MR scan have been used to evaluate lymphangiomas, which appear as large multicystic fluid-filled masses. CT and MR Imaging findings are often helpful in distinguishing lymphangiomas from various vascular disorders. We report the findings of CT, MRI and bone scan in a patient with generalized cystic lymphangiomatosis. Whole body 3.0-T MR scan using STIR sequence with a larger FOV could detect the additional lesions that were not seen at other imaging modalities. We believe that whole body 3.0 T MR imaging is a good modality to evaluate the extent of the disease and following up the patients with the generalized cystic lymphangiomatosis.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.175-181
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• 2001

본 연구의 목적은 사람들이 언어과제와 공간지각과제을 수행하는 동안 활성화되는 뇌 영역의 차이를 규명하는 것이다. 428명의 대학생을 대상으로 집단 심리실험을 수행하여, fMRI 연구를 위한 실험참여자로 17명의 오른손잡이 여대생을 선정하였다. 17명 중 8명은 언어능력은 뛰어나지만 공간지각능력이 떨어지고, 나머지 9명은 언어능력은 빈약하지만, 공간지각능력이 우수한 사람들이었다. fMRI 실험에 사용된 패러다임에는 언어과제와 공간지각과제가 각각 8block으로 구성되었으며, 각 block은 동일한 과제 3문항을 포함하였다. fMRI 이미징은 1.5T Siemens Vision Scanner로 수집되었으며, Single-shot EPI 기법으로 (TR/TE : 3840/40ms, flip angle : 90, FOV : 220, 64x64 matrix) 이미지를 스캔하였다. 자료분석은 SPM-99 소프트웨어를 사용하였다. 감산(subtraction)분석결과, 언어능력이 뛰어난 집단에서는 양측 대상회(bilateral cingulate gyri)와 좌측 상두정엽 (left superior parietal lobe)이 더 많이 활성화되었고, 언어능력이 떨어지는 집단에서는 양측 전두엽 (both frontal lobes)이 더 많이 활성화되었다. 공간지각능력이 떨어지는 집단에서는 우측 시상 (right thalamus)과 좌측 측-후두엽 (left temporooccipital)이 더 많이 활성화되었다. 언어능력이나 공간지각능력이 우수한 집단에서는 공통적으로 대상회 (cingulate gyri)가 활성화되었다.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.493-504
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• 2007

This paper proposes a stereo vision-based forward obstacle detection and distance measurement method. In general, stereo vision-based obstacle detection methods in automotive applications can be classified into two categories: IPM (Inverse Perspective Mapping)-based and disparity histogram-based. The existing disparity histogram-based method was developed for stop-and-go applications. The proposed method extends the scope of the disparity histogram-based method to highway applications by 1) replacing the fixed rectangular ROI (Region Of Interest) with the traveling lane-based ROI, and 2) replacing the peak detection with a constant threshold with peak detection using the threshold-line and peakness evaluation. In order to increase the true positive rate while decreasing the false positive rate, multiple candidate peaks were generated and then verified by the edge feature correlation method. By testing the proposed method with images captured on the highway, it was shown that the proposed method was able to overcome problems in previous implementations while being applied successfully to highway collision warning/avoidance conditions, In addition, comparisons with laser radar showed that vision sensors with a wider FOV (Field Of View) provided faster responses to cutting-in vehicles. Finally, we integrated the proposed method into a longitudinal collision avoidance system. Experimental results showed that activated braking by risk assessment using the state of the ego-vehicle and measuring the distance to upcoming obstacles could successfully prevent collisions.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.581-586
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• 2002

The development of 2-D radiometer is a new technical challenge for space borne remote sensing area. The Y-type antenna array has been proposed as a most efficient configuration because a large alias free FOV and a small-synthesized beam-width can be achieved compared to L-, T-type under the fixed antenna spacing. New configuration of antenna array, which is called sub-Y type configuration, is proposed to obtain a higher angular resolution than the case of Y-type array in the paper. The sub-Y type array is consisted of basic arrays, which are the Y-type array of four antenna elements. To analyze characteristics of the proposed configuration, the synthesized beam pattern is simulated through simulation. The secondary effect of the sub-Y-type is that the reconstructed image is suffered from the alias effect is appeared around the real target. The ghost targets in the reconstructed image can be reduced by the alias suppression algorithm introduced in this paper. In conclusion, the performance evaluation by use of array factor simulation shows more than 37.5% improvement in average for angular resolution and almost similar performance for temperature resolution.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1934-1935
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• 2011

In order for a service robot to perform several tasks, basically autonomous navigation technique such as localization, mapping, and path planning is required. The localization (estimation robot's pose) is fundamental ability for service robot to navigate autonomously. In this paper, we propose a new system for point pattern matching based visual global localization using spot lightings in ceiling. The proposed algorithm us suitable for system that demands high accuracy and fast update rate such a guide robot in the exhibition. A single camera looking upward direction (called ceiling vision system) is mounted on the head of the mobile robot and image features such as lightings are detected and tracked through the image sequence. For detecting more spot lightings, we choose wide FOV lens, and inevitably there is serious image distortion. But by applying correction calculation only for the position of spot lightings not whole image pixels, we can decrease the processing time. And then using point pattern matching and least square estimation, finally we can get the precise position and orientation of the mobile robot. Experimental results demonstrate the accuracy and update rate of the proposed algorithm in real environments.

• Journal of Astronomy and Space Sciences
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• v.22 no.1
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• pp.47-58
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• 2005

This paper addresses development of the ultra-light analog sun sensors for small satellite applications. The sun sensor is suitable for attitude determination for small satellite because of its small, light, low-cost, and low power consumption characteristics. The sun sensor is designed, manufactured and characteristic-tested with the target requirements of ${\pm}60^{\circ}$ FOV (Field of View) and pointing accuracy of ${\pm}2^{\circ}$. Since the sun sensor has nonlinear characteristics between output measurement voltage and incident angle of sunlight, a higher order calibration equation is required for error correction. The error was calculated by using a polynomial calibration equation that was computed by the least square method obtained from the measured voltages vs. angles characteristics. Finally, the accuracies of 1-axis and 2-axes sun sensors, which consist of 2 detectors, are compared.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.402-403
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• 2018

70GHz-band high gain array antenna is developed for automotive short range radar sensor. In Short-rangeradar, the gain must be high in order to increase the resolution, and the angle width must be set to secure the field of view(Fov). The proposed antenna operates at 76~81GHz and satisfies angle width $60^{\circ}$, antenna gain 15dB and the input reflection coefficient of less than -10dB within the operating frequency. Wave guide WR-10 was used to measure the antenna and results similar to the simulation results were obtained.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.601-603
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• 2004

Multi-Spectral Camera(MSC) is a payload on the KOMPSAT -2 satellite to perform the earth remote sensing. The instrument images the earth using a push-broom motion with a swath width of 15 km and a ground sample distance (GSD) of 1 m over the entire field of view (FOV) at altitude 685 Km. The instrument is designed to have an on-orbit operation duty cycle of $20\%$ over the mission lifetime of 3 years with the functions of programmable gain! offset and onboard image data compression/storage. MSC instrument has one(1) channel for panchromatic Imaging and four(4) channel for multi-spectral Imaging covering the spectral range from 450nm to 900nm using TDI CCD Focal Plane Array (FPA). In this paper, the configuration, the interface of MSC hardware and the MSC operation concept are described. And the method of the MSC calibration are described and the design of MSC calibration operation to measure the change of MSC after Launch & Early Operation(LEOP) and normal mission operations are discussed and analyzed.

• Journal of the Optical Society of Korea
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• v.16 no.1
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• pp.63-69
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• 2012

This paper presents a method to derive the theoretical requirements for the development of a 400 mm optical window that transmits dual-band wavelengths and had a stable structure. We also present design and fabrication results. Among the required specifications, the surface figure error was defined by the transmitted wavefront deformation (TWD), ${\lambda}$/15 rms at 632.8 nm. This value was derived by estimating the predicted performances with respect to five independent items that could cause system performance degradation and then calculating the required wavefront error (WFE) to satisfy the performance goals. We measured the image resolution at each performance level to trace and verify the requirements. The article also describes a design optimization process that could minimize the weight and volume of the optical window attached to the payload securing the FOV of the camera. In addition, we accurately measured the deformation that occurred in the series of fabrication steps including processing, coating, assembly, bonding and bolting, and investigated the effects by comparing them to the results of a simulation performed in advance to derive the predicted performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12A
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• pp.1990-1999
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• 2001

This paper presents a dynamic simulation loop that gives tracking results of 2-color concentric annular ring (CAR) reticle seeker. Our simulation tool includes the target/flare model and a proportional navigation guidance (PNG) loop. The CAR reticle system performances and the flare effects are analyzed in various scenarios. When a flare is present in the field of view (FOV), the simulation results show that the reticle seeker cannot keep a precise target tracking. In this paper, we propose 2-color counter-countermeasure (CCM) using the least mean square (LMS) method to cope with a presence of IR flare. The proposed method makes a simultaneous process in two infrared (IR) wavelength bands: MWIR add SWIR. The simulation results have shown that our adaptive IRCCM algorithm can achieve an effective cancellation of the flare signal with a relatively high intensity.