• International Journal of Highway Engineering
• /
• v.10 no.2
• /
• pp.125-133
• /
• 2008

Achieving consistent geometric design is an important goal in highway design to ensure obtaining safe, economical and smooth traffic operation. Most evaluation of consistency is based on 'speed change' in speed profile. According to literature, the speed depends on geometric elements, speed on tangent section prior to a curve, and background around roads. Especially, the radius is the most main element mentioned in various literature. Therefore, this paper shows two ways of calculating horizontal radius on real road, that is, three-dimensional road. First of all, the radius of horizontal curve is calculated based on physical method. The calculated radius contains not only superelevation but also longitudinal grade while the current minimum radius is calculated by considering superelevation and side friction according to the point-mass equation. Secondly, the problem of composed curves with distorted appearance by overlaying sag or crest vertical alignment has been known. To quantify the extent of distortion effects, the method of calculation of real seen so called 'Perspective Radius' is developed. The paper presents the perspective radius and recommended perspective radius.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.1
• /
• pp.49-56
• /
• 2004

Load imbalance is a serious impediment to achieving good performance in parallel processing. Global load balancing schemes cannot adequately manage to balance parallel tasks generated from a single application. Dynamic loop scheduling methods are known to be useful in balancing parallel loops on shared-memory multiprocessor machines. However, their centralized nature causes a bottleneck for the relatively small number of processors in a network of workstations because of order-of-magniture differences in communication overheads. Moreover, improvements of basis loops scheduling methods have not effectively dealt with irregularly distributed workloads in parallel loops, which commonly occur in applications for a network of workstation. In this paper, we present a new reconfigurable and decentralized balancing method for parallel loops on a network of workstations. Since our method supplements performance balancing with those tranditional load balancing methods, it minimizes the overall execution time.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.6 no.4
• /
• pp.345-356
• /
• 2004

Open-cut method has been widely used to construct underground structures, but it causes several problems such as traffic congestion and public resentment resulting from severe construction noise and ground settlement. In many cases, it is very difficult to build underground structures safely due to the unknown locations of buried facilities such as water pipes, drainage pipes, gas pipes and high-pressure cable conduits etc. Also in open-cut method, moving buried facilities causes additional cost and extension of construction period. Therefore, this paper is to present a case study in which Tubular Roof construction Method (T.R.c.M.), a newly developed construction method for underground structures using slab steel pipes and PC wall trench, is applied for the construction of a subway tunnel in Seoul. As a result, it is found that T.R.c.M. is a construction method by which tunnels can be constructed safely without any effect on the surrounding environment and traffic flow due to the minimized construction vibration and noise.

• Korean Chemical Engineering Research
• /
• v.50 no.6
• /
• pp.1043-1048
• /
• 2012

In this study, activated carbons (ACs) were modified as electrode materials for an electric double layer capacitor (EDLC) by controlling oxygen- and nitrogen-containing functional groups. The morphological and chemical properties of ACs were analyzed through scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectrometer, automatic elemental analyzer (EA) and Boehm titration. Also, charge/discharge tests were performed to investigate the EDLC performance. Oxygen- and nitrogen-containing functional groups were introduced on the surface of ACs through acid and urea treatments, respectively. ACs with nitrogen-containing functional groups showed 2 mA increase of gravimetric discharge capacity and quick achievement of maximum charge/discharge performance. However, ACs with oxygen-containing functional groups showed low discharge capacity and its gradual decrease during further cyclic test, since the functional groups interrupted adsorption/desorption of charges in the electrolyte on the surface of ACs.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.9
• /
• pp.1043-1049
• /
• 2014

In this paper, we design and implement a digital LCD stopwatch function of the remote control. The central controller and LCD stopwatch is implemented based on the clock signal of the crystal oscillator of 8MHz by using ATmega8 processor in the AVR representative series of ATMEL, Communication module basic, ZBS-using the ISM 2.4GHz frequency band at 100. Stopwatch of remote control that has been proposed, it is possible to solve the three problems. First, it is possible to solve the sight deviation between broadcast camera and panelists glance to large LCD stopwatch monitors. Second, it is possible to avoid the trouble of broadcasting cameras cross replacement, Third, it is possible to minimize the inconvenient of the viewer corresponding to the operation of the horizontal movement of the broadcast camera.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.46 no.4
• /
• pp.70-76
• /
• 2009

We proposed the device to control a computer mouse with only head movements and eye blinks so that disabilities by car or other accidents can use a computer. The mouse position were estimated from a gyro-sensor which can measure head movements, and the mouse events such as click/double click were from opto sensors which can detect the eyes flicker, respectively. The sensor was mounted on the goggle in order not to disturb the visual field. There was no difference in movement speed between ours and a general mouse, but it required 3$\sim$4 more times in the result of the experiment to evaluate spatial movements and events detection of the proposed mouse because of the low accuracy. We could eliminate cumbersome work to periodically remove the accumulated error and intuitively control the mouse using non-linear relative point method with dead zones. Optical sensors are used in the event detection circuitry designed to remove the influence of the ambient light changes, therefore it was not affected in the change of external light source.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.11 no.3
• /
• pp.70-80
• /
• 2012

In Vehicular Ad-hoc Network(VANET) which constructs networks without fixed infrastructure among vehicles, network topology is frequently changed due to high mobility. In case of urban model, communication disconnections caused by interruptions of communication propagation such as buildings and constructions could be often occurred. Therefore, in VANET environment a routing protocol to complement its characteristics is needed. This paper suggests an algorithm to improve the transmission performance at intersections by approaching of the distance-based broadcasting which utilizes the information of vehicle's position. By using relative velocity among vehicles, it makes the stability of route decision improved and reduces packet collisions through graded priorities in the intersection, and simultaneously improves the performance of data rate. It can be seen that the performance compared with previous algorithm is significantly improved when using the suggested algorithm in the urban traffic environment.

• Journal of the HCI Society of Korea
• /
• v.1 no.1
• /
• pp.29-36
• /
• 2006

Tactile displays can provide useful information without disturbing others and are particularly useful for people with visual or auditory impairments. They can also complement other displays. In this paper, we present a new vibrotactile display device for wearable, mobile, and ubiquitous computing environments. The proposed vibrotactile device has a $5{\times}5$ array configuration for displaying complex information such as letters, numbers, and haptic patterns as well as simple directional ques and situation awareness alarms. Commercially available coin-type vibration motors are embedded vertically in flexible mounting pads in order to best localize vibrations on the skin. An embedded microprocessor controls the motors sequentially with an advanced tracing mode to increase recognition rate. User studies with the vibrotactile device on the top of the foot show 86.7% recognition rate for alphabet characters after some training. In addition, applying vibrotactile device to driving situation shows 83.9% recognition rate. We also propose some potentially useful application scenarios including Caller Identification for mobile phones and Navigation Aids for GPS systems while driving.

• Journal of Digital Convergence
• /
• v.18 no.2
• /
• pp.261-268
• /
• 2020

Machine learning is achieved by making a cost function from a given digital signal data and optimizing the cost function. The cost function here has local minimums in the cost function depending on the amount of digital signal data and the structure of the neural network. These local minimums make a problem that prevents learning. Among the many ways of solving these methods, our proposed method is to change the learning step-size. Unlike existed methods using the learning rate (step-size) as a fixed constant, the use of multivariate function as the cost function prevent unnecessary machine learning and find the best way to the minimum value. Numerical experiments show that the results of the proposed method improve about 3%(88.8%→91.5%) performance using the proposed method rather than the existed methods.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2012.02a
• /
• pp.487-487
• /
• 2012

플라즈마 디스플레이 패널(PDP)은 공정 절차가 간단하고 가격 경쟁력이 매우 뛰어나 일찌감치 대형 평판 디스플레이 시장을 주도해 왔으며 빠른 응답 속도를 기반으로 한 생생한 화질의 구현으로 3D TV 시장에서도 꾸준한 사랑을 받고 있다. 향후 더 큰 화면을 요구하는 PID(Public Information Display) 시장에서도 PDP 는 두각을 나타낼 수 있을 것으로 보인다. 하지만 PDP 는 여전히 LCD, OLED 등의 디스플레이에 비해 발광 효율이 낮고 소비 전력이 높다는 단점을 가지고 있다. 또한 미국 환경청(EPA)과 에너지부(DOE)가 공동으로 마련한 전자 제품의 효율 등급제인 에너지 스타(Energy Star) 제도가 끊임없이 개편되면서 소비 전력에 대한 규제가 점차 강화되고 있기 때문에 발광 효율 및 소비 전력 특성의 개선은 현재 PDP 업계가 해결해야 할 가장 중요한 과제라고 할 수 있다. 발광 효율의 개선과 관련하여 최근에는 PDP의 보호막으로 널리 쓰이고 있는 MgO 보다 2차 전자 방출 계수가 높아 PDP의 구동 전압을 낮추는 동시에 휘도와 발광 효율 특성을 개선시킬 수 있는 신 보호막에 대한 연구가 활발히 이루어지고 있다. MgO를 대체 가능한 신 보호막으로 언급되는 물질은 SrO 혹은 CaO 등이 대표적이다. 하지만 이러한 물질들은 공기 및 수분에 대한 용해도가 높기 때문에 증착된 막이 이후의 공정 과정(합착 및 가열 배기 등)에서 대기 중에 노출 될 경우 심하게 변질될 수 있다. 이러한 문제점을 해결하기 위해서 신 보호막 위에 기존의 MgO 보호막을 얇게 증착하여 공기로부터의 접촉을 차단하거나 펠렛을 제조하는 과정에서 MgO 에 신 보호막 물질을 소량만 첨가하는 등의 방법들이 제안되어 왔으며 그 결과 기존의 PDP 대비 구동 전압을 낮추고 발광 효율을 획기적으로 개선하는데 성공한 결과들이 지속적으로 보고되고 있다. 하지만 신 보호막이 공기 및 수분에 민감한 만큼, 고온의 공정으로 인해 PDP의 하판 유리로부터 상판에 증착된 박막으로 확산되는 불순물에 의해서도 오염되며 이 역시 신 보호막의 특성을 구현하는데 방해 요소로 작용한다. 본 연구에서는 PDP 하판의 불순물이 상판의 박막으로 확산되는 것을 방지하고자 하판 형광체 인쇄전 PECVD 증착법으로 확산 방지막을 1 가량 형성하였다. 이후 SIMS 분석을 통하여 하판 불순물의 확산이 효과적으로 차단됨을 확인하였고 신 보호막의 오염을 최소화하여 결과적으로 PDP의 구동 전압을 낮추고 효율을 획기적으로 개선하는데 기여할 수 있음을 확인하였다.