Recursive load balance scheme for two-tier cellular networks using enhanced inter-cell interference coordination

Hong, Myunghoon,Park, Seungyoung SpringerOpen 2015 Eurasip Journal on Wireless Communications and Net Vol.2015 No.-

흡인성 폐렴 환자에서의 비디오투시 연하검사의 빈도와 특성

Myunghoon Moon,고성화,신용일,Ji-Hong Min 대한연하장애학회 2018 대한연하장애학회지 Vol.8 No.1

Objective: This study was conducted to identify the frequency of videofluoroscopic swallow study (VFSS) and characteristics of VFSS findings in the patients diagnosed with aspiration pneumonia. Method: We retrospectively reviewed the medical records of 2,885 patients who has been diagnosed with aspiration pneumonia either clinically or radiographically. Overall, 811 patients could not be examined because of medical problems. The rest of the subjects were divided into two groups according to the presence of neurologic deficit. The findings of VFSS were scored using the Penetration-Aspiration Scale (PAS) and Pharyngeal Residue Grade (PRG), and data were analyzed based on descriptive statistics, the χ2 test, t-test, ANCOVA and logistic regression. Result: A total of 1,267 subjects (43.9%) underwent VFSS. Among patients who could be examined, 61.1% were tested. Only 26.7% of subjects without neurologic deficit underwent VFSS, while 56.5% of the subjects in the other group underwent the procedure. The PAS and PRG scores did not differ significantly between groups. About 32.7% of the findings showed silent aspiration (PAS 8), which difficult to detect by bedside screening tests. Conclusion: Subjects with neurologic deficit showed significantly higher test rates than the others. There were no significant differences in VFSS findings between groups. Dysphagia should be evaluated in patients with aspiration pneumonia using precise tools, such as VFSS and fiberoptic endoscopic evaluation of swallowing (FEES), regardless of presence of neurological deficit.

제동시 발생하는 리어 드럼브레이크 grunt (stick-slip) noise 개선

홍일민(Ilmin Hong),장명훈(Myunghoon Jang),김선호(Sunho Kim),최홍석(Hongseok Choi) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.10

Grunt (Stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

제동시 발생하는 리어 드럼브레이크 Grunt(stick-slip) Noise 개선

홍일민(Ilmin Hong),장명훈(Myunghoon Jang),김선호(Sunho Kim),최홍석(Hongseok Choi) 한국소음진동공학회 2013 한국소음진동공학회 논문집 Vol.23 No.9

Grunt(stick-slip) noise happens between rear lining and drum on braking condition while vehicle is returning to steady position after nose-dive. The study presents a new testing and analysis methods for improving brake grunt noise on vehicle. Grunt noise is called a kind of stick slip noise with below 1 kHz frequency that is caused by the surfaces alternating between sticking to each other and sliding over each other with a corresponding change in friction force. This noise is typically come from that the static friction coefficient of surfaces is much higher than the kinetic friction coefficient. For the identification of the excitation mechanism and improvement of grunt noise, it is necessary to study variable parameters of rear drum brake systems on vehicle and to implement CAE analysis with stick slip model of drum brake. The aim of this study has been to find solution parameters throughout test result on vehicle and dynamo test. As a result of this study, it is generated from stick slip between rear lining and rear drum and it can be solved to reduce contact angle of lining with asymmetric and is effected not only brake drum strength but also rear brake size and brake factor.

Development of a MATLAB toolbox for parametric robust control

Noriko Hyodo,Myunghoon Hong,Hitoshi Yanami,Hirokazu Anai,Shinji Hara 제어로봇시스템학회 2006 제어로봇시스템학회 국제학술대회 논문집 Vol.2006 No.10

뇌졸중 환자의 구음장애와 흡인과의 상관관계

Eun-Ho Yu,Myunghoon Moon,Ji-Hong Min,Hye-Kyung Kim,신용일,고현윤,So Jung Kim,고성화 대한연하장애학회 2020 대한연하장애학회지 Vol.10 No.1

Objective: This study examined the correlation between dysarthria and aspiration to determine if dysarthria canpredict aspiration in stroke patients. Methods: The medical records of 176 patients with first stroke, who underwent a videofluoroscopic swallowing study(VFSS) and Urimal test of articulation and phonology (U-TAP) at the same time between January 2012 and December2015 in the authors’ hospital, were reviewed retrospectively. The correlation between the penetration aspirationscale (PAS) score and U-TAP score was analyzed in all patients. The mean PAS score and frequency of each PAS scorein the dysarthria group and non-dysarthria group were compared. In addition, the aspiration was analyzed based onthe severity of dysarthria in the dysphagia group. All statistical analyses were performed using SPSS software. Results: The correlation between the PAS score and U-TAP score was not statistically significant in all the subjects. The mean PAS score was 3.46±5.52 and 3.07±5.49 in the dysphagia and non-dysphagia group, respectively. The meanPAS score of the dysphagia group was higher than that of the non-dysphagia group. On the other hand, it was notstatistically significant. In addition, there was no significant difference in the frequency of the PAS scores betweenthe two groups. The aspiration was compared with the severity of dysarthria according to the U-TAP score; therewas no statistically significant difference. Conclusion: No correlation was observed between dysarthria and aspiration in stroke patients. In addition, there wasno difference in the frequency of aspiration with or without dysarthria. According to the results of this study, aspirationcannot be predicted by dysarthria in stroke patients. Therefore, each diagnostic test and assessment shouldbe performed for each symptom.

Development of A Five Inter-Row Type Weeding Device for A Paddy Field Robot

( Gookhwan Kim ),( Daehyun Lee ),( Myunghoon Lee ),( Gilsu Han ),( Hyundong Lee ),( Youngki Hong ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

Recently, eco-friendly agriculture has been spreading demand for safe food production in accordance with the increase of interest of people in health and environment. Manual work is the best way to remove weeds while reducing the use of herbicides, but it is time consuming and costly. This study introduced the structure and operation principle of a five inter-row type weeding device which physically removes weeds without herbicide, and tested and analyzed the performance of the device. This weeding device was covered with a polyethylene cover to prevent damage to the rice seedlings, and cutting blades were mounted in the inside of the cover to perform the weeding works. The blades were consisted of one 'L'-shaped form rotating blade and four fixed blades. The horizontal part of the rotating blade along with the fixed blade cuts weeds like scissors, and the vertical part is put into the topsoil and does a role to cut and stir the roots of weeds. The power of the weeding device is offered by the high torque through the Power Takeoff (PTO) of the robot. Since the rotating speed provided by the PTO is not enough to perform the weeding operation, the accelerator was mounted between the PTO of the robot and the rotating shaft of the weeding device to increase the rotation speed. The transmitted torque is distributed to each part of the weeding device composed of a five inter-row type through a system of pulleys and belts. An important consideration in developing a weeding device to use in a paddy field is how well the device follows the irregular and soft surface conditions like a paddy environment. To solve this problem, the weeding device was designed and manufactured with the following features. (1) A pair of rotating wheels were attached to both sides of the device so that the device could proceed stably along the irregular surface of a paddy field without sinking into the mud. (2) The weeding parts of five were connected to one rod to cope with the change of pitch angle which varies according to the state of the surface when both wheels run along the road surface of a paddy. (3) Even though both wheels run along the road surface, the roll angle is changed due to the difference in height of the both sides. To cope with this, a board-type spring and a roller-type bearing were mounted. (4) The brackets which both sides wheels are fixed are able to perform linear motion by up and down in accordance with the change in the height of the road surface together with the rod on which the devices were mounted. This weeding device was attached on the robot which can travel following rice seedlings rows in a paddy field, and performed weeding works. The result measuring the rate of weeding and the rate of rice seedlings damage, total amounts of cutting were 20.92kg, the rice seedlings were 0.22kg. The rate of the damage was just less 1.05%.

Development of A Dual Steering Type Orchard Robot Platform of Front-Rear Wheel for Unmanned Works

( Gookhwan Kim ),( Daehyun Lee ),( Myunghoon Lee ),( Gilsu Han ),( Hyundong Lee ),( Youngki Hong ),( Yunsu Do ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

When farm works are carried out in an orchard like apple and pear by machinery, there are many cases that the condition of the orchards is irregular and inclined. As a result, not only the number of farmers casualties caused by overturn of agricultural machinery and working devices is increasing, but also frequent damage due to excessive harmful pesticide inhalation of agricultural workers is occurring. To reduce these damages, we have developed a robotic platform that can carry out agriculture work while autonomously traveling in orchard. In the early stages of the development of the orchard robot, it was designed and manufactured to suit the size of general orchards (apple: 3~4m width and pear: 5~6m width) rather than making a robot which can apply to whole orchard. Also, irregular roads due to gravels and puddles are considered, but the slope is limited to a maximum of 10 degrees (except for terraced fields). The size of this robot developed for the unmanned work in orchard is 2.8 m(L) x 1.5 m(W) x 1.2 m(H) and the weight is 750 kg in the state without working devices. The maximum steering angle is ± 22 degrees. The distance between the front and rear wheels is 1.7 m, and the turning radius is about 3.11 m. Both front and rear wheels were equipped with each 1.5kW motor for driving of the robot and a worm gear type speed reducer is attached to the 750W motor for steering. One of the characteristics of the orchard robot proposed in this study is that it was designed and manufactured with a dual steering type of front and rear wheels. In the case of a general four-wheel moving vehicle, that is, a front or rear wheel steering type vehicle, in the process of following tree rows using sensors fixed to the robot, the direction angle of the robot is frequently being changed. Because of it, the robot gets moved zigzag form and the data for following of the tree row also must be modified in accordance with the change of the direction angle. It makes the follow of tree row be complicated. However, in the case of a dual steering type of front and rear wheels, when recognizing and following both sides tree row of the robot, the path following is executed in the method that both front and rear wheels are controlled simultaneously. That is, the robot moves in parallel shift without the change of the direction angle to follow the tree row. This not only makes it possible for the robot to travel accurately in the middle of the both sides tree row, but it also has the advantage of simplifying the calibration and path following algorithm of the sensor data.

벼농사 로봇을 위한 5조식 제초 작업기

김국환 ( Gookhwan Kim ),이대현 ( Daehyun Lee ),이명훈 ( Myunghoon Lee ),한길수 ( Gilsu Han ),이현동 ( Hyundong Lee ),홍영기 ( Youngki Hong ) 한국농업기계학회 2017 한국농업기계학회 학술발표논문집 Vol.22 No.2

최근 친환경 농업은 건강과 환경에 대한 많은 사람들의 관심 증폭에 발맞춰 안전한 식품의 생산 요구가 확산되고 있다. 제초제의 사용을 줄이면서 잡초를 제거하기 위해서는 수작업이 가장 좋은 방법이나, 시간과 비용이 많이 든다. 본 연구는 제초제 없이 5조식 제초 작업기의 구조 및 동작 원리를 설명하고 제초기의 성능에 대해 시험, 분석해 보았다. 제초 작업기는 PE, 재질의 커버를 사용하여 모 손상을 방지하였고, 내부에는 절단식 제초날을 장착하여 제초작업을 수행할 수 있도록 하였다. 제초날은 하나의 ㄱ자형 회전날과 4개의 고정날로 구성되어 있는데, 회전날의 수평부는 고정부와 같이 가위처럼 잡초를 절단하고 수직부는 논 표토에 놓여 잡초의 뿌리까지 절단, 교반하는 역할을 수행한다. 제초 작업기의 동력은 로봇의 PTO 장치를 통해 고토크의 회전력을 얻어 구동한다. PTO 장치의 회전속도를 가속시키기 위해 가감속기를 동력 전달부와 회전축 사이에 장착하였고, 5조의 제초 작업기에 병렬로 회전력을 전달하는 방식으로 설계, 제작하였다. 제초 작업기를 개발함에 있어 중요한 고려 사항은 5조의 작업기가 무논환경과 같이 연약지면서 불규칙한 노면상태를 얼마나 잘 추종하는 것이다. 이를 해결하기 위해 5조식 제초 작업기는 다음과 같은 특징으로 설계, 제작하였다. 첫째, 제초작업기의 양 측에 한 쌍의 자전식 바퀴를 달아 제초 작업기가 안정적으로 노면을 따라 진행할 수 있도록 하였다. 둘째, 하나의 축에 5조의 제초 작업기를 연결하여 양 측 바퀴가 노면을 따라 주행할 때 노면의 높낮이에 따라 변하는 피치(pitch)각 변화에 대응할 수 있도록 하였다. 셋째, 양측 바퀴가 노면을 따라 진행하더라도 양 측의 높낮이가 다르면 롤(roll)각이 변하게 되는데, 이에 대응하기 위하여 판스프링과 롤러 형태의 베어링을 장착하였다. 또한, 작업기의 양 측 모서리에 스프링을 장착하여 원래의 위치로 복원될 수 있도록 하였다. 넷째, 양 측 바퀴를 고정시킨 브라켓은 작업기가 장착된 축과 함께 노면의 높낮이 변화에 맞춰 상하로 직선 운동을 할 수 있도록 하였다. 이러한 특징들로 인해 연약하면서 불규칙한 무논 환경에 유연하게 대응하면서 제초작업을 수행할 수 있도록 하였다. 이렇게 개발된 제초 작업기를 제초로봇에 장착하여 제초 작업을 수행하였다. 시험포장의 주요 잡초는 물달개비였고, 10조 × 50 m 구간을 대상으로 제초작업을 수행하여 제초량 및 모 손상율을 파악해 보았다. 제초 작업을 수행한 후, 절단되거나 분쇄된 잡초와 모를 수거하여 총 중량을 측정한 결과, 총 제초 중량은 20.92 kg, 손상모의 양은 0.22 kg, 잡초량은 20.7 kg으로 전체 제초량 중 모 손상율은 1.05% 미만임을 알 수 있었다. 이는 1회의 제초 작업을 통해 얻은 결과이다.

이중 조향 방식의 과원 내 무인 작업용 로봇 개발

김국환 ( Gookhwan Kim ),이대현 ( Daehyun Lee ),이명훈 ( Myunghoon Lee ),한길수 ( Gilsu Han ),이현동 ( Hyundong Lee ),홍영기 ( Youngki Hong ),도윤수 ( Yunsu Do ) 한국농업기계학회 2017 한국농업기계학회 학술발표논문집 Vol.22 No.2

사과와 배 같은 과원 내에서 농작업을 수행할 때 불규칙하고 경사진 노면을 주행하는 경우가 많은데 농기계 및 작업기의 전복 사고로 인한 농민 사상자가 증가하고 있을 뿐 아니라 방제 시 농작업자의 과도한 유해성 농약 흡입으로 인한 빈번한 피해가 발생하고 있다. 이러한 피해를 줄이고자 과원 내에서 무인으로 자율주행을 하면서 농작업을 수행할 수 있는 로봇 플랫폼을 개발하였다. 과원 로봇의 개발 초기 단계에서는 모든 과원에서 적합한 로봇을 만들기보다 한국의 일반적인 사과(3~4 m폭) 및 배(5~6 m폭) 과원 내에서의 주행에 적합하도록 설계, 제작하였다. 또한, 자갈 및 웅덩이들로 인한 불규칙한 노면은 고려하되 최대 10도의 경사지에 국한하여 개발하였다(계단식 과원은 제외). 레이저센서를 로봇의 앞뒤에 장착하여 과수열을 검출하여 경로를 추종할 수 있고, 다음 작업열에 대한 진입이 용이하도록 하였고, 고정식 장애물이 인식되면 회피하거나 이동식 장애물이 사라질 때까지 정지해 있다가 주행할 수 있도록 하였다. 또한, 관성측정장치를 장착하여 로봇의 자세에 따른 레이저 센서 데이터를 보정하였고, 로봇의 과수열 추종 능력을 검증하기 위하여 실시간GPS (RTK-GPS)를 장착하였다. 과원 내 무인 작업을 위해 개발된 로봇은 작업기가 장착되지 않은 크기는 2.8 m(L) × 1.5 m(W) × 1.2 m(H)이고, 무게는 약 750 kg이다. 조향을 위한 최대 조향각은 ±22도이고, 전후륜의 축간 거리는 1.7 m로 회전반경은 약 3.11 m이다. 구동방식은 전후륜 모두 1.5 kW의 모터를 장착하였고 조향을 위해 750 W급의 모터에 웜기어 형태의 감속기를 장착하여 구동축에 연결하였다. 본 연구에서의 제안한 과원 로봇의 특징 중 하나는 전·후륜 이중 애커먼 조향 방식으로 설계, 제작되었다는 것이다. 일반적인 4륜 이동체(전륜조향)의 경우 과수열 추종을 위해 진행각이 변하여 지그재그형태로 로봇이 경로를 추종하게 되어 진행각 변화에 따라 데이터 보정도 해야 되고, 로봇이 똑바로 진행할 수 있도록 해야 하여 보다 복잡한 알고리즘이 필요하다. 또한, 좁은 구간에서는 일정하게 작업 상태가 유지되기 어렵다. 하지만, 전·후륜 이중 조향 방식의 경우 로봇 양 옆의 과수열을 인식하여 생성한 경로 추종을 위해 평행 이동하는 형태로 로봇을 이동시켜 경로를 추종한다. 이는 로봇이 과수열 중간에 정확히 놓여 이동할 수 있도록 해 줄 뿐 아니라, 레이저 센서 데이터의 보정 및 경로 추종 알고리즘을 간단하게 해주는 장점이 있다.