• Proceedings of the Korean Information Science Society Conference
• /
• 2001.04a
• /
• pp.376-378
• /
• 2001

원격 진료 또는 원격 강의와 같은 신뢰적인 멀티캐스트 다자간 통신에서는 멀티캐스트 기능 뿐 만 아니라, 모든 수신자에게 신뢰적인 정보 전들을 요구한다. 이를 위해, 네트워크 자원을 효과적으로 이용하고, 재전송 데이터의 전달 시간 단축, 그리고 그룹 멤버의 가입/이탈 시의 손쉬운 멤버쉽 관리를 위해서는 멀티캐스트 트리를 구성해야 한다. 본 논문에서 제안한 멀티캐스트 구성 알고리즘은 송신자가 수신자에 의해 전송되는 ICMP 메시지의 학장을 이용하여 송신자로부터 수신자까지의 경로를 계산하고, 그 경로에 따라서 최소 비용 멀티캐스트 트리를 구성하는 방법이다. 본 알고리즘은 다른 계층의 프로토콜과는 독립적으로 동작할 수 있고, ICMP 메시지 확장뿐만 아니라, IP 옵션의 확장을 통해서도 제공될 수 있다. 본 논문에서는 최근 인터넷 표준 초안으로 제안된 ICMP 메시지 확장을 기반으로 기술하였다. 본 알고리즘을 통해 적정한 재정 재전송자와 재전송 도메인이 구성되는 것을 간단한 프로그래밍을 통해 확인 할 수 있었다.

• Proceedings of the KIEE Conference
• /
• 2004.05a
• /
• pp.144-146
• /
• 2004

It is known that Global Positioning System(GPS) is the most efficient navigation system because it provides precise position information on the all areas of Earth regardless of metrology. Until now, the size of GPS receivers has become smaller and the performance of receivers has become higher. So receivers provide the position information of not only static system but also dynamic system. Usually, users make similar movement trajectory according to their life pattern and it is possible to build up efficient database by collecting only the repeated users' position. Because position information calculated by the receiver is erroneous about 10-30m within 5% error tolerance, the position information is oscillated even on the same area. In this paper, we propose the system that can estimate whether users are out of trajectory or in dangerous situation by soft-computing method.

• Journal of IKEEE
• /
• v.26 no.4
• /
• pp.602-613
• /
• 2022

This paper proposes an algorithm for correcting indirect situations resulting from the wheelchair moving the stairs with wheel-type caterpillar and seat position variable. For analyzing the Yawing movement model, the change of Yaw value was estimated using Roll, Pitch, and Yaw in the driving environment, and it was used as a control variable and the information of the wheel drive controller. The verification confirmed the correction of about 10° of Yawing movement within about 7 seconds. It was confirmed that the angular velocity was reduced by 47.5% in seat position change.

• Journal of Korea Multimedia Society
• /
• v.16 no.9
• /
• pp.1089-1097
• /
• 2013

The applications for considering their position and daily patterns of dementia patients have been developed in an early stage even if the older patients who have weaker or serious symptoms has increased in various forms. In this paper, we develop an android-based application which displays positions and pathways of patients on maps and provide messages in the cases of dangerous situations. Guardians need to register schedules including safe areas and personal information of their patients. This system registers behavior status categorized as normal or abnormal each position which is sent to a database. In particular, the deviation status is assigned in case the patients are not within the safe areas that their guardians registered on their schedule. The wandering status is assigned in case the patients are repeatedly passed by their pathways. This smart application contains the modules such as patient position sending, guardian and patient information, patient schedule and safe zone registration, position and behavior status registration, pathway display and message sending, and rescue request. This system sends the notification and alarm service providing normal and abnormal behavior with deviation and wandering status of patients respectively.

• Journal of Chest Surgery
• /
• v.35 no.6
• /
• pp.449-453
• /
• 2002

Intra-aortic balloon pump (IABP) is well known for its hemodynamic benefit but still has its own complications. Proper use of IABP is the best way to obtain maximum benefit with low complication rate. Material and Method： Twenty one(men 10, female 11) patients were included in this study among the 100 consecutive adult cardiac surgery patients in our hospital. Eighteen(85.7%) were ischemic heart disease patients. They all received IABP therapy due to postcardiotomy cardiogenic shock according to the well-known indications. Their preoperative conditions, intraoperative factors including hemodynamics, postoperative conditions and IABP-related complications were analyzed. Result： Nineteen patients(90.5%) were successfully weaned from IABP. There were 2 patients of operative death and the mortality rate was 9.5%. Duration of IABP use was 40.7$\pm$24.3 hours. There were 2 cases(9.5 %) of IABP-related vascular complications that required surgical intervention. Conclusion： We concluded that IABP could be used effectively and safely for postcardiotomy cardiogenic shock patients with low complication rate.

• Korean Journal of Child Studies
• /
• v.35 no.4
• /
• pp.103-122
• /
• 2014

The purpose of this study was to identify the variables affecting parenting efficacy of North Korean refugee mothers. The selected variables were marital satisfaction, social support, and acculturation. The participants consisted of 105 mothers who had defected from North Korea with preschool children living in Seoul, Gwangmyeong-si, and Gyeongsangnam-do provinces. The data thus collected were analyzed by descriptive statistics, t-tests, correlation, and multiple regression analysis. The results indicated that the marital satisfaction and social support had meaningfully positive effects on the parenting efficacy of North Korean refugee mothers. However, marginalization was found to be a predictor of competence-anxiety in parenting. The selected variables derived from the environmental systems in maternal parenting were significant factors in the parenting efficacy of North Korean refugee mothers and furthermore, their sociocultural environments were also important in parenting. These findings clearly showed that marital satisfaction and social support were the most significant variables of parenting efficacy of North Korean refugee mothers. The results of this study appear to have a great deal of utility as preliminary data to improve the parenting efficacy of North Korean refugee mothers.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2023.11a
• /
• pp.100-102
• /
• 2023

항로추종성능은 자율운항선박(MASS)의 중요한 자율제어기능 중 하나이다. 이는 선박의 안전성을 보장하기 위해 중요하며, 자율운항선박의 설계 단계에서 사전 평가가 필수적이다. 본 연구는 자율운항선박의 항로추종성능 평가를 위한 전산유체역학(CFD) 모델과 LOS 알고리즘 연계 방안을 제안한다. 먼저, 자율운항선박의 정수 중 거리 이탈 편차를 이용한 항로 추종 성능 평가 모델 개발에 관하여 기술했다. 먼저, 항로 추종을 수행하는 선박 주변의 난류 흐름은 비압축성 뉴턴 유체의 가정하에 비정상 RANS(Reynolds Averaged Navier-Stokes) 법을 이용하여 수치적으로 계산되었다. 중첩격자계법을 CFD 모델에 적용함으로써 거리 이탈 편차를 이용하는 LOS(Line-of-Sight) 가이던스 알고리즘에 의한 타의 회전 및 이에 따른 선체의 6 자유도 움직임을 CFD 환경에서 구현하였다. 개발된 자유 항주 선박 CFD 모델을 이용하여 항로 추종 시뮬레이션 평가 결과, 설정된 항로에서 선박의 정수 중 항로 추종 제어는 파도, 조류, 및 바람과 같은 외부 교란의 부재로 LOS 알고리즘에 의한 우현/좌현 측 변침뿐만 아니라 직진 경로의 추종도 성공적으로 수행됨을 확인하였다. 선체, 프로펠러, 타의 복잡한 상호작용을 정도 높게 해석할 수 있는 자유 항주 선박 CFD 모델과 LOS 알고리즘의 결합은 자율운항선박의 항로 추종 성능 평가를 정량적으로 평가하는 데 기여할 것으로 기대된다.

• Journal of the Institute of Convergence Signal Processing
• /
• v.22 no.2
• /
• pp.79-84
• /
• 2021

The most important device of the AGV is the guide sensor, and the typical function of this sensor is high accuracy and extraction of the road. If the accuracy of the guide sensor is low or the sensor device is extracted the wrong track, this causes the problems such as the AGV collision, track-out, the load falling due to AGV swing. In order to improve these problems, this study is proposed a signal processing method of the guide sensor based on multi-maskings and the center of gravity method, and evaluated its performance. As a result, the proposed method showed that the mean error of absolute value is 2.32[mm] and it showed performance improvement of 27[%] than the center of gravity method of existence. Therefore, when the proposed signal processing method is applied, It is thought that the posture control and driving stability of the AGV will be improved.

• Journal of the Korean Orthopaedic Association
• /
• v.55 no.5
• /
• pp.405-410
• /
• 2020

Purpose: Pedicle screw insertion has been traditionally used as a surgical treatment for degenerative lumbar spine disease. As an alternative, the cortical-bone trajectory screw allows less invasive posterior lumbar fixation and excellent mechanical stability, as reported in several biomechanical studies. This study evaluated the clinical and radiological results of a case of early failure of cortical-bone screw fixation in posterior fixation and union after posterior decompression. Materials and Methods: This study examined 311 patients who underwent surgical treatment from 2013 to 2018 using cortical orbital screws as an alternative to traditional pedicle screw fixation for degenerative spinal stenosis and anterior spine dislocation of the lumbar spine. Early fixation failure after surgery was defined as fixation failure, such as loosening, pull-out, and breakage of the screw on computed tomography (CT) and radiographs at a follow-up of six months. Results: Early fixation failure occurred in 46 out of 311 cases (14.8%), screw loosening in 46 cases (14.8%), pull-out in 12 cases (3.9%), and breakage in four cases (1.3%). An analysis of the site where the fixation failure occurred revealed the following, L1 in seven cases (15.2%), L2 in three cases (6.5%), L3 in four cases (8.7%), L4 in four cases (8.7%), L5 in four cases (8.7%), and S1 in 24 cases (52.2%). Among the distal cortical bone screws, fixation failures such as loosening, pull-out, and breakage occurred mainly in the S1 screws. Conclusion: Cortical-bone trajectory screw fixation may be an alternative with comparable clinical outcomes or fewer complications compared to conventional pedicle screw fixation. On the other hand, in case with osteoporosis and no anterior support structure particularly at L5-S1 fusion sites were observed to have result of premature fixation failures such as relaxation, pull-out, and breakage.

• Journal of Advanced Navigation Technology
• /
• v.15 no.5
• /
• pp.839-844
• /
• 2011

Various technologies such as infrared light, ultrasonic waves, RFID, GPS, UWB, and signal indicators have been incorporated in the location tracking system. However, such pre-existing systems require location recognition in shadow areas. This study proposes a location tracking system that utilizes Cooperative Spectrum Sensing. Cooperative Spectrum Sensing is not only able to track the location and path of moving objects but also recognize when objects breakaway from the path set by sensors and guide them back. In addition, it has the advantage of being more efficient in terms of frequency usage. It is able to automatically fix power transmission and frequency modulation for transmission cognitive users to an optimum level within the range that does not cause interference for primary users.