• Proceedings of the KOSOMBE Conference
• /
• v.1994 no.12
• /
• pp.43-46
• /
• 1994

A new spatial localization technique using high-order surface gradient coil (SGC) is proposed. Although the Spatial Selection with High-Order gradient (SHOT) can provide a 2-D selection with only one selective RF pulse, the high-order gradient produced by cylindrical-shape coils has not been clinically useful for clinical systems due to the large minimum selection size caused by the limited radial gradient intensity. However, by using the proposed high-order SGCs located near the imaging region, the size of volume selection can be reduced to a clinically useful 1-4 cm in diameter by applying stronger radial gradient with much less gradient driving power. A 40 cm-by-40 cm $r^{2}$ SGC has been designed and constructed, and phantom and volunteer studies have been performed. Experimental results using spatially localized MRI show good agreement to the theoretically predicted behavior.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.7A
• /
• pp.654-661
• /
• 2011

RTLS (Real-time locating systems) are used for tracking the location of people or assets in real time. In this system, RTLS readers continuously communicate with RTLS tags for measuring time or ranges and location engine tries to calculate accurate location of tags. However, when we attempt to apply this system to real world, the non-line-of-sight(NLOS) problem can be critical to the system performance because of the obstacles. In this paper, we suggest a new location estimation method for an NLOS environment using a reader-selection strategy. We have implemented all components of the locating system and carried out experiments in a test-bed. The accuracy of the system is 50% better than that of the existing general locating system.

• Journal of Institute of Control, Robotics and Systems
• /
• v.13 no.10
• /
• pp.1025-1031
• /
• 2007

GPS is widely used for positioning applications and attitude of a vehicle can be found also with multiple antennas. However, extremely weak signal level prevents GPS from indoor operation. DR with accelerometers and gyros and landmark based localization method used for indoor applications increase complexity and cost. In this paper, a simple but very efficient ultrasound based attitude determination system which determines both position and attitude in WSN is given. The range between transmitter and receivers are measured using the arrival time difference between ultrasound and RF signal. The 3 dimensional positions can be found using more than 3 range measurements. Furthermore, if more than 2 transmitters are used, the attitude can be determined using the baseline vectors obtained by differencing transmitter and receiver positions. The prototype system is implemented to evaluate the performance of the proposed method. In addition, an error analysis shows the relation between the attitude error and basel me length, quality of measurement and orientation of a vehicle. The static and dynamic experiments performed by micro mobile robot shows accurate position with less than 1.5cm error and attitude with less than 1 degree error can be obtained continuously with 20cm baseline. It is expected that these results can be adapted without modification to indoor applications such as home cleaning robot and autonomous wheelchair maneuvering.

• The KIPS Transactions:PartC
• /
• v.16C no.5
• /
• pp.615-620
• /
• 2009

Nowadays, wireless infrastructures such as sensor networks are widely used in many different areas. In case of sensor networks, the wirelessly connected sensors can execute different kind of tasks in a diversity of environments, and one of the most important parameter for a successful execution of such tasks is the location information of each node. As to localization problems in WSNs, there are ToA (Timer of Arrival), RSS (Received Signal Strength), AoA (Angle of Arrival), etc. In this paper, we propose a modification of existing ToA and RSS based methods, adding a weighted average scheme to measure more precisely the distance between nodes. The comparison experiments with the traditional ToA method show that the average error value of proposed method is reduced by 0.1 cm in indoor environment ($5m{\times}7m$) and 0.6cm in outdoor environment ($10{\times}10m$).

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.1117-1120
• /
• 2005

위치응용 서비스는 유비쿼터스 컴퓨팅의 구현의 기반이 되는 중요 기술요소 중 하나이다. 특히 스마트 홈, 지능형 단말기, 스마트 스페이스의 구현을 위해서는 광역범위보다는 실내환경에서의 사용자, 오브젝트의 위치인식에 대한 연구기술이 필요하다. 본 논문에서는 무선센서 플랫폼 및 통신기술을 이용한 실내 위치인식 시스템의 설계 및 구현에 관해 기술하고자 한다. 사용자 위치인식을 위한 기반기술로 RF 무선신호와 초음파신호간의 속도차를 이용한 DTOF 기반 거리측정과 삼각측량 기법을 이용하였다. $3{\sim}10cm$ 의 위치오차를 가지는 정밀 위치계측 기술로, 개발된 시스템은 무선센서 플랫폼과 임베디드 게이트웨이 시스템, 위치계측 서버 시스템으로 구성되며, 시스템의 개발 및 실제환경에서의 테스트를 통하여 실생활 응용에 대한 가능성을 확인할 수 있었다. 또한 오차보정 및 멀티 센서를 통한 위치보정기법에 대해서도 논의한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2007.10d
• /
• pp.366-371
• /
• 2007

무선 센서 네트워크는 경제적, 환경적 목적으로 다양한 방면에서 활용되고 있다 이 때, 배치된 각 센서의 위치를 파악하는 것은 센서 네트워크에서 가장 기본적이며 가장 중요한 문제 중의 하나이다. 기존 논문에서 제안된 센서 위치 측정 방법은 특별한 장비를 장착하거나 특정한 환경의 지역에 한정시킨 방범으로 제한하고 있는 경우가 대부분이다. 하지만 어떠한 관심 지역의 환경은 언제라도 바뀔 수 있다. 또한, 센서가 위치할 환경의 기온, 풍속 등을 미리 안다는 것은 비현실적인 가정이다. 더구나 각각의 센서에 특별한 장비를 장착한다는 것은 비용 절감을 이유로 센서 네트워크를 운영하는 경우 오히려 그것을 이용하지 않는 경우보다 비용이 더 들 수도 있다. 이에 본 논문에서는 센서 노드의 기본적인 통신 기능은 이용하여, 환경에 순응적으로 센서의 위치를 측정할 수 있는 방법을 제안하고자 한다. 센서 노드에서 기본적으로 제공하는 통신 기능은 RF 전파를 보낼 때 전송 레벨을 달리하여 보낼 수 있다. 이러한 기본적인 기능을 이용하여 위치를 측정하게 되면 전체적인 센서 네트워크의 비용이 절감될 뿐만 아니라 환경에 순응적인 위치 측정이 가능하게 된다. 또한, 각 노드의 위치가 정해진 후 다른 노드와 통신할 때 전파의 세기를 조정함으로써 RF 통신에서 소모되는 전력량을 줄일 수 있다. 따라서 본 논문에서 제안하는 전송 레벨을 이용한 위치 측정 방법은 단순히 위치를 측정한다는 의미뿐 아니라 환경에 순응적으로 작동한다는 장점이 있다. 향후 네트워크 내에서 통신에 소비되는 전력을 줄일 수 있다는 점에서도 중요한 의미를 지닌다.를 집행하는 caspase의 활성 형태인 cleaved caspase-8, -9, -7, -3의 단백질 수준이 목향 헥산추출물의 처리에 의해 증가하였고 caspase-3의 표적 단백질 중 하나인 PARP의 불활성 형태인 cleaved PARP의 단백질 수준도 현저하게 증가하였다. 이 결과들은 목향 헥산 추출물이 LNCaP 세포의 apoptosis를 유도함으로써 전립선 암세포의 증식을 억제함을 보여주는 것이며 목향 헥산추출물에 의한 apoptosis 유도는 caspase 활성 증가와 Bak 및 t-Bid 단백질의 증가에 의한 것임을 제시한다. 따라서 앞으로 항암효과를 나타내는 성분의 동정 및 동물실험을 통하여 좀 더 면밀한 기전 연구가 수행된다면 목향 헥산추출물은 화학적 암예방 물질이나 치료제로 개발될 수 있을 것으로 사료된다.적 분해층과 마모질이가 가장 깊은 것으로 나타났으며 flowable type의 복합레진과 컴포머는 표면 경도와 마모도에서 양호한 결과를 보였다. 이상의 결과 복합레진과 컴포머의 평가요소로서 마모도와 함께 가수분해도 고려되어야 할 것으로 사료된다.증후군 환자에서 대조군에 비해 높은 비율을 보였다.er thinning은 3 군모두에서 관찰되었고 항암 3 일군이 가장 심하게 나타났다. 이상의 실험결과를 보면 술전 항암제투여가 초기에 시행한 경우에는 조직의 치유에 초기 5 일정도까지는 영향을 미치나 7 일이 지나면 정상범주로 회복함을 알수 있었고 실험결과 항암제 투여후 3 일째 피판 형성한 군에서 피판치유가 늦어진 것으로 관찰되어 인체에서 항암 투여후 수술시기는 인체면역계가 회복하는 시기를 3

• Journal of Korean Neurosurgical Society
• /
• v.37 no.2
• /
• pp.105-111
• /
• 2005

Objective: Tremor, either essential tremor or Parkinsonian tremor, has been effectively and safely treated by lesioning the ventral intermediate(Vim) nucleus of the thalamus with or without mircroelectrode recording. The authors evaluate the treatment outcome of sixteen tremor patients who had been treated with thalamotomy without microelectrode. Methods: Between September, 2001, and December, 2003, sixteen tremor patients were treated with thalamotomy without microelectrode recording. Twelve patients suffered from Parkinsonian tremor and four patients were essential tremor patients. The male to female ratio was 1.6 to 1 with median age of 59.6 years (range; 39-74 years). Under local anesthesia, a 3mm hole was made using a hand-held twist drill, and the dura mater was penetrated with a 1.2mm sharp drill beat. Radiofrequency(RF) electrode was placed in the Vim nucleus of thalamus. With intraoperative macrostimulation, RF lesion was made. Postoperative CT scan and/or MR imaging was performed to confirm the localization of the target lesioned. Preoperative and postoperative tremor was evaluated with simple tremor severity scale and the development of complications related with the procedure was closely reviewed at the immediate postoperative period and the last follow-up. Results: It produces immediate relief in up to 98.4% of the patients. There were no development of complications related with procedure, all patients discharged one or two days after surgery. Conclusion: Vim thalamotomy without microelectrode recording is a safe and effective procedure to control the tremor with minimal morbidity. Intraoperative macroelectrode stimulation safely localizes the Vim nucleus target of the thalamus for the treatment of patients with tremor.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.331-339
• /
• 2016

This paper developed a home wellness robot platform to perform the roles in basic health care and life care in an aging society. A robotic platform and a sensory platform were implemented for an indoor wellness service. In the robotic platform, the precise mobility and the dexterous manipulation are not only developed in a symbiotic service-robot, but they also ensure the robot architecture of human friendliness. The mobile robot was made in the agile system, which consists of Omni-wheels. The manipulator was made in the anthropomorphic system to carry out dexterous handwork. In the sensing platform, RF tags and stereo camera were used for self and target localization. They were processed independently and cooperatively for accurate position and posture. The wellness robot platform was integrated in a real-time system. Finally, its good performance was confirmed through live indoor tests for health and life care.

• Proceedings of the KOSOMBE Conference
• /
• v.1996 no.11
• /
• pp.161-164
• /
• 1996

An actively-shielded $r^{2}$-gradient coil has been developed for brain localized MRI or MRS. Spatial localization is very useful for spatial volume selection in MRI or MR Spectroscopy(MRS). The radial(or $R^{2}-$) gradient coil is useful in reducing the artifact or in improving the SNR by selecting the volume with less number of RF pulses. It is, however, difficult to implement the coil with a gradient intensity strong enough to use it for practical whole-body MRI system. For example, the smallest volume size for selection is just 6 cm in diameter with a 250 Ampere of current driving for a whole-body system (in case of 70-cm-diameter). In this study, an asymetric $r^{2}$-coil with a small diameter of 35 cm has been designed and implemented for brain localized MRI or MRS. An 8-rod high-pass-type birdcage RF coil has also been implemented. The coil set has been developed for 1.0 Tesla Medison MRI system and its performance has been verified experimentally.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.7 no.2
• /
• pp.71-78
• /
• 2012

Based on the Zigbee-based wireless sensor network, I suggest the way to reduce errors between the short distance, improving the accuracy of the presumed distance by revising the deviation of RSSI(Received Signal Strength Indication) values is to estimate the distance using only the RF signal power without the additional hardware. In general, the graph measured by RSSI values shows the proximity values which are ideally reduced in proportion to the distance under the free outdoor space in which LOS(Line-Of-Sight) is guaranteed. However, if the result of the received RSSI values are each substituted to the formula, it can produce a larger margin of error and less accurate measurement since it is based upon the premise that this free space is not affected by reflected waves or obstacles caused by the ground and electronic jamming engendered by the environment. Therefore, the purpose of this study is to reduce the margin of errors between the distances and to measure the proximity values with the ideal type of graph by suggesting the way to revise the received RSSI values in the light of these reflected waves or obstacles and the electronic jamming. In conclusion, this study proves that errors are reduced by comparing the proposed deviation correction method to the revised RSSI value.