• Journal of the Korea Society of Computer and Information
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• v.24 no.11
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• pp.29-39
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• 2019

As mobile robot applications increase in real life, the need of low cost autonomous driving are gradually increasing. We propose a novel vision-based real-time lane detection and tracking system that supports autonomous driving of mobile robots in constrained tracks which are designed considering indoor driving conditions of mobile robots. Considering the processing of lanes with various shapes and the pre-adjustment of operation parameters, the system structure with multi-operation modes are designed. In parameter tuning mode, thresholds of the color filter is dynamically adjusted based on the geometric property of the lane thickness. And in the unstable input mode of curved tracks and the stable input mode of straight tracks, lane feature pixels are adaptively extracted based on the geometric and temporal characteristics of the lanes and the lane model is fitted using the least-squared method. The track centerline is calculated using lane models and the motion model is simplified and tracked by a linear Kalman filter. In the driving experiments, it was confirmed that even in low-performance robot configurations, real-time processing produces the accurate autonomous driving in the constrained track.

• International Area Studies Review
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• v.21 no.2
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• pp.3-20
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• 2017

Traditional co-integration analysis method is known to be difficult to clearly determine the relationship between the cointegrated variables. This study utilizes a fractional cointegation method and a causal analysis of time and frequency domain among the exchange rates of Korea, China and Japan. The results show that even though traditional cointegration methods did not clarify the existence of cointegration, exchange rates were fractionally cointegrated. Causal analysis of time domain and frequency domain provided somewhat different results, but the yen/dollar was useful for forecasting won/dollar and yuan/dollar. Proper use of causal analysis of frequency domain and fractional cointegration emthods may provide useful information that can not be explained from the traditional method.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.39-46
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• 2023

We present an efficient packet transmission strategy for massively multiplayer online first-person shooter (MMOFPS) games using movement-adaptive packet transmission interval. The player motion in FPS games shows a wide spectrum of movement variability both in speed and orientation, where there is room for reducing the number of packets to be transmitted to the server depending on the predictability of the character's movement. In this work, the degree of variability (nonlinearity) of the player movements is measured at every packet transmission to calculate the next transmission time, which implements the adaptive transmission frequency according to the amount of movement change. Server-side prediction with a few auxiliary heuristics is performed in concert with the incoming packets to ensure reliability for synchronizing the connected clients. The comparison of our method with the previous fixed-interval transmission scheme is presented by demonstrating them using a test game environment.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.31 no.2
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• pp.47-55
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• 2022

Food impaction due to proximal space opening after implant restoration is a very common phenomenon in patients who have implant prosthesis. This occurs because the movement mechanism between the implant and the tooth is different, and it occurs about 30-60% over time. Contributing factors include the arch (mandible), region (posterior teeth), adjacent teeth (non-vital teeth), and antagonist teeth (natural teeth or implants), etc. While this phenomenon cannot be prevented, efforts should be made to minimize it. In order to have an ideal proximal contact as much as possible, the concave shape or the prominent lower proximal shape should be modified to create a symmetrical proximal shape. with the buccal dentate in the upper third height should be adjusted. Other conditions should be modified so that the heights of the marginal ridges are similar. Since an irregular occlusal plane is a cause of poor prognosis, food impaction should be minimized by restoring the ideal occlusal plane by correcting the extruded antagonist and reduction of the disto-buccal cusp.

• Journal of the Korea Society of Computer and Information
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• v.27 no.6
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• pp.23-31
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• 2022

Due to the recent outbreak of COVID-19 and an aging population and an increase in single-person households, the amount of time that household members spend doing various activities at home has increased significantly. In this study, we propose an algorithm for detecting anomalies in members of single-person households, including the elderly, based on the results of human movement and fall detection using an image sensor algorithm through home CCTV, an activity sensor algorithm using an acceleration sensor built into a smartphone, and a 2D LiDAR sensor-based LiDAR sensor algorithm. However, each single sensor-based algorithm has a disadvantage in that it is difficult to detect anomalies in a specific situation due to the limitations of the sensor. Accordingly, rather than using only a single sensor-based algorithm, we developed a fusion method that combines each algorithm to detect anomalies in various situations. We evaluated the performance of algorithms through the data collected by each sensor, and show that even in situations where only one algorithm cannot be used to detect accurate anomaly event through certain scenarios we can complement each other to efficiently detect accurate anomaly event.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.35 no.2
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• pp.41-48
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• 2023

In this study, simplified linear numerical method that can simulate wave generation and transformation by a moving bottom is introduced. Numerical analysis is conducted in wave number domain after continuity equation, linear dynamic and kinematic free surface boundary conditions and linear kinematic bottom boundary condition are Fourier transformed, and the results are expressed in space domain by an inverse Fourier transform. In the wavenumber domain, the dynamic free water surface boundary condition and the kinematic free water surface boundary condition are numerically calculated, and the velocity potential in the mean water level (z = 0) satisfies the continuity equation and the kinematic bottom boundary condition. Wave generation and transformation are investigated when the triangular and rectangular shape of bottoms move periodically. The results of the simplified numerical method are compared with the results of previous analytical solutions and agree well with them. Stability of numerical results according to the calculation time interval (Δt) and the calculation wave number interval (Δk) was also investigated. It was found that the numerical results were appropriate when Δt ≤ T(period)/1000 and Δk ≤ π/100.

• Journal of the Korean earth science society
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• v.43 no.6
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• pp.661-679
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• 2022

Plate tectonics, with the continental drift theory and later strongly supported by the sea-floor spreading theory with evidence of paleo-geomagnetic fields, ocean floor sediments, successfully explained the slow but continuous movements of rigid lithospheres in geological time. Initially, plate motions were described as relative movements between adjacent plates, mainly based on paleo-geomagnetic reversal data. The advent of space geodetic techniques in the 1980s enabled direct measurements of plate velocities and assessment of deformations within certain regions. In this review, early relative plate motion models are briefly summarized, the no-net-rotation frame theory and corresponding models are explained, and the characteristics of the most recent models that incorporate intraplate deformation are described. Additionally, the plate motion section of the International Terrestrial Reference Frame is introduced, and a few recent case studies of local plate motion are briefly described; for example, in South America, Europe, Antarctica, and Turkey. Finally, studies of plate motion in northeastern Asia focusing on the Korean Peninsula are introduced.

• Journal of TMJ Balancing Medicine
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• v.12 no.1
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• pp.28-31
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• 2022

위에서 살펴본 바와 같이 나는 급성 턱관절장애의 경우, 첫번째 유형은 주로 턱관절 디스크공간의 문제와 하악의 위치를 바로잡아주는 근육의 문제가 주 원인일 것으로 추정하고 있다. 만약 턱관절 디스크공간이 정상공간이라면 턱의 지그재그 움직임이나 턱관절잡음, 턱통증, 턱탈구, 그리고 개구장애 등이 발생할 수 없기 때문이다. 그리고 근육의 문제 중에서는 턱관절 디스크원판을 양측에서 잡아주는 내외측 익돌근의 문제가 가장 많은 영향을 미치고 있다. 특히 내측 익돌근의 긴장 및 수축이 디스크 원판을 내측으로 빠져나가게 함으로써 하악의 좌우 지그재그 움직임을 야기시키고 턱관절잡음이나 턱통증 및 개구장애를 유발하기 때문이다. 나머지는 저작에 관여하는 근육들이 그 다음으로 영향을 미치는 것으로 예측하고 있다. 그러나 제2형 급성 턱관절장애의 경우는 제1형 급성 턱관절장애가 한단계 더 발전하여 이와 연관된 근육이나 인대의 긴장수축이 오랜 시간 진행되어, 이들이 다시 상부 경추의 아탈구와 두개골의 비정상적 움직임에까지 영향을 미쳐 나타나는 것으로 생각된다. 그렇게 되면 뇌에서 필요 충분한 뇌혈액공급이나 뇌척수액순환의 문제를 일으킬 수 있기 때문이다. 그리고 제1형 만성 턱관절장애의 경우는 제2형 급성 턱관절장애가 좀 더 진행되면서 척추 및 근골격계의 구조변화, 교합 및 턱의 구조변화 그리고 안면구조의 변화에 이르기까지 점점 진행되어 나타나는 것으로 보인다. 따라서 각종 척추 디스크질환, 관절질환을 비롯해서 두개천골계의 순환문제, 부정교합 및 턱 비대칭, 안면 비대칭의 문제를 유발하게 된다고 추정된다. 그러나 두번째 유형의 만성 턱관절장애는, 턱에서 지속적이고 반복적인 그리고 과다한 부정적 자극들이 오랜 기간 누적되면서 턱에 분포된 C 섬유를 비롯한 3차신경의 가소성변화를 유발하면서 결국 중추신경계를 포함하여 전체신경계의 회로망에까지 파급되어 다양한 만성질환 또는 난치성 질환들이 양산되는 것으로 추정하고 있다. 아마도 지금까지 서양의학에서 아직 밝혀내지 못한 대부분의 질병들이 여기에 포함되지 않을까 하는 것이 나의 생각이다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.36 no.2
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• pp.70-79
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• 2024

In this study, we introduce a linear spectral method capable of simulating wave generation and transformation caused by a moving bottom in a 3-dimensional space. The governing equations are linear dynamic free-surface boundary conditions and linear kinematic free-surface boundary conditions, which are solved in Fourier space. Solved velocity potential and free-surface displacement should satisfy continuity equation and kinematic bottom boundary condition. For numerical analysis, a 4th order Runge-Kutta method was utilized to analyze the time integral. The results obtained in Fourier space can be converted into velocity potential and free-surface displacement in a real space using inverse Fourier transform. Regular waves generated by various types of moving bottoms were simulated with the linear spectral method. Additionally, obliquely generated regular waves using specified bottom movements were simulated. The results obtained from the spectral method were compared to analytical solutions, showing good agreement between the two.

• Journal of Life Science
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• v.19 no.8
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• pp.1152-1158
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• 2009

For the toxicological pathologic study of amanita muscaria, we have investigated single and repeated dose toxicity in Sprague-Dawley (SD) rats. Single dose toxicity study was identified as catalepsy, incline and tail pinch methods (control 0 mg/kg, low 3.3 mg/kg, middle 16.5 mg/kg, high 33.0 mg/kg). Repeated dose toxicity study was carried out in blood tests, serum tests and histopathological methods. Neurotoxicity - muscle paralysis, and convulsion and loss of movement - was observed at 33.0 mg/kg group in the single dose toxicity study. Dysfunction of liver and kidney were shown in the repeated oral administration of the amanita muscaria at 3${\sim}$4 weeks. Serum chemistry results revealed a marked increase of LDH [Lactate Dehydrogenase (3181.5 IU/L; normal 230-460 IU/l)], ALT [Alanine transaminase (124.0 IU/l; normal <40 IU/l)] but the kidney was normal. Histopathological results show interstitial edema and tubular epithelial necrosis in the kidney. These results suggest that amanita muscaria has a neurotoxic effect and causes dysfunction of liver and kidney in the SD rat.