• Journal of the Korea Society of Computer and Information
• /
• v.12 no.6
• /
• pp.229-234
• /
• 2007

In the IEEE 802.11 Wireless Local Area Networks (WLANs), network nodes experiencing collisions on the shared channel need to backoff for a random period of time. which is uniformly selected from the Contention Window (CW) This contention window is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. The BEB scheme suffers from a unfairness problem and low throughput under high traffic load. In this paper, I propose a new backoff algorithm for use with the IEEE 802.11 Distributed Coordination Function.

• IEMEK Journal of Embedded Systems and Applications
• /
• v.7 no.5
• /
• pp.227-239
• /
• 2012

Recent advances in electronics have enabled various conventional products to incorporate with numerous powerful microcontroller. Generally, an embedded system is a computer system designed for specific control functions within a larger system, often with real-time computing constraints. The growing performance and reliability of hardware components and the possibilities brought by various design method enabled implementing complex functions that improve the comport of the system's occupant as well as their safety. A cyber physical system (CPS) is a system featuring a tight combination of, and coordination between, the system's computational and physical elements. The concept of cyber physical system, including physical elements, cyber elements, and shared networks, has been introduced due to two general reasons: design flexibility and reliability. This paper presents a cyber physical system where system components are connected to a shared network, and control functions are divided into small tasks that are distributed over a number of embedded controllers with limited computing capacity. In order to demonstrate the effectiveness of cyber physical system, an unmanned forklift with autonomous obstacle avoidance ability is implemented and its performance is experimentally evaluated.

• Journal of Construction Engineering and Project Management
• /
• v.3 no.3
• /
• pp.35-41
• /
• 2013

All infrastructure projects are said to be inter-dependent, uncertain and labour-intensive in nature. There is no exception for building services sub sector. For a real time project such as 'The construction, extension and refurbishment of Employees' State Insurance Corporation (ESIC) Hospital at Tirupathy, India with total area of 45,000 square feet at an estimated cost of 1100 million rupees, a generic process model is developed to simulate the effect of set of identified variables on construction project. The 'Stocks and Flows' of dynamic model affords relevant insights to project managers, who apply this knowledge when designing better performance through more appropriate project planning. It is concluded from the model-based approach that building services works can be improved through specific better focussed managerial efforts, such as an increasing coordination effectiveness at the planning stage, clarifying prerequisite conditions prior to installations. Otherwise, pending works arising from work clashes can lead to knock-on effects resulting in productivity constraints and pressures, as well as more rework and demolition. Current study reveals that the model enables deep insight into various interdependent processes, their by improving construction performance levels, by addressing the dynamics of design errors and defective works, and recovering delayed schedule.

• The Journal of Fisheries Business Administration
• /
• v.28 no.1
• /
• pp.1-26
• /
• 1997

The Proposal of this paper is to draw up solution about fishing disputes in Korea coastal waters. Small fishing vessels under 8 metric tons which is regulated by the provincial governors, must operate within provincial boundary on the sea as in fishery policy of Korea. on this, I think that the present situations of fishing disputes have related to the fishing license system. Problem of this kind, Before 1970's, fishing disputes rarely took place, and it, if any, did not bring any social conflicts or disputes. Since 1980's, some of fishing disputes have been reported within fisheries society Recently, The disputes have been increasing to become social conflicts between local people concerned and have evoked an argument on whether the provincial boundary on the sea exists. If such disputes continues to increases or remains unsolved, they will bring a tremendous social cost such as an accelerated decrease in fish resources, degradation of fishing grounds, disorder in fishing, destruction of fisheries culture and so on. The reasons for the growing disputes can be specified as fellows : the degradation of fish resources, the present fishing license system which inherently causes competitions in fish catching, irrational ceiling system of fishing vessels, legal problem on existing boundary between neighbouring two provinces, the functional problem of national or regional fishery coordination committee which has been established to coordinate general fishing disputes. This study has also dealt with Japan's experiences in fishing disputes which has the history of more than a hundred years and its coordinating mechanism. In the discussion section, some possible solutions have been briefly touched fer further study.

• Tunnel and Underground Space
• /
• v.27 no.5
• /
• pp.295-302
• /
• 2017

In this study, a new quantitative instrumentation and measurement standards applicable to the field of mining has been proposed to improve the problems of the current measurement practices that apply the measuring standards of the civil engineering field (road, railway, etc.). With the data coordination of the mine reclamation corporation, we collected data on ground subsidence in the abandoned mine area, and studied various techniques for establishing a new management reference value based on the manual measurement data measured in the field. As a result, new instrumentation and measurement standards is set up and proposed by using statistics like the average value, the third quartile, the 95% confidence, and the maximum value.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.3
• /
• pp.543-550
• /
• 2016

The Active Superconducting Current Controller (ASCC) is a new type of Superconducting Fault Current Limiters (SFCL) which can limit the fault current in different modes. It also has the particular abilities of compensating active and reactive powers for electrical networks. In this paper, it is confirmed that the performance of ASCC in different operating modes introduces a limiting impedance in series with the network which can even degrade the transient stability and the operation of the Over-Current Relays (OCR) employed in a power system. In addition, the model of a three-phase ASCC is simulated, and the effect of descriptive modes on the current limiting level is investigated. For the transient stability analysis, a single machine-infinite bus system is tested, and the effect of operation modes is studied based on an equal area criterion obtaining the critical time and the critical angle. Modifying the setting parameters of OCR such as time dial and pick-up current, the protective coordination is also studied in different operating modes.

• The Research Journal of the Costume Culture
• /
• v.15 no.3 s.68
• /
• pp.541-549
• /
• 2007

Goguryo is the ancient dynasty which established the system of ancient state earlier than Baekje and Sila, and was a strong political and military power. Unlike the rock carving works of prehistoric times, mural paintings composed of line and color tones in tombs are characterized more by its social aspect and symbolism as a serious form of art than other cultural heritage of Goguryo. In response to that, this study analyzed the dress and ornaments of women found in Anak No. 3 ancient tomb, Susan-ri ancient tomb, Ssangyeongchong, which are the ancient tombs in Pyeongyang from 4th century to 5th century, have relatively more ancient tombs than any other places and preserved the mural paintings well, by using the plate, slide, literature and data related to relics in order to figure out the characteristics of women's dress and ornament in Goguryo, and the lifestyle and social aspect of Goguryo.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2007.10a
• /
• pp.91-94
• /
• 2007

In the IEEE 802.11 Wireless Local Area Networks (WLANs), network nodes experiencing collisions on the shared channel need to backoff for a random period of time, which is uniformly selected from the Contention Window (CW). This contention window is dynamically controlled by the Binary Exponential Backoff (BEB) algorithm. The BEB scheme suffers from a fairness problem and low throughput under high traffic load. In this paper, I propose a new backoff algorithm for use with the IEEE 802.11 Distributed Coordination Function.

• Journal of Korean Critical Care Nursing
• /
• v.2 no.1
• /
• pp.26-35
• /
• 2009

Purpose: This paper reviews current diagnostic evaluation, treatment, nursing considerations, and the nurse practitioner’s (NP) role in acute ischemic stroke care. Methods: National guidelines and extensive literature on acute stroke care were reviewed and a relevant clinical case was introduced. Results: Computerized tomography (CT) of the head without contrast is the initial brain imaging procedure for patients with an acute stroke. Magnetic resonance imaging (MRI) can be an alternative test. Restoration of cerebral perfusion to the affected area is a key therapeutic strategy for ischemic stroke. A number of treatment strategies such as thrombolysis, anticoagulation, antiplatelet, and surgical treatment can be selected to improve blood flow to the ischemic region. The NP on the stroke team is involved with immediate stroke management including neurological assessment, ensuring adequate oxygenation, blood pressure management, activity, and diet. Discharge planning with the patient, family teaching and coordination of follow up care should also be implemented early in the hospitalization. Conclusion: The nurse practitioner is one of the cardinal members on the stroke team, and must be updated with current treatment and management guidelines.

• Proceedings of the KIEE Conference
• /
• 2003.07a
• /
• pp.558-560
• /
• 2003

The effects of surge arresters for protection of transmission systems against direct lightning strokes have already been investigated using the digital simulation program EMTP. Distribution lines are spanned on a much large area as compared to transmission lines, and therefore, are more often susceptible to lightning strokes. This paper analyzes the overvoltages on underground cable system against direct lightning strokes to the overhead ground wire using the digital simulation. The effects of lightning protection methods, such as lowering the grounding resistance and installing the surge arrester, for preventing overvoltages on underground cable system caused by direct lightning strokes to the overhead ground wire is investigated. Several schemes have been proposed to protect underground cables. This paper summarizes the main results of a study aimed at analysis of lightning overvoltages in variety underground feeders protected by metal-oxide arresters. This study will provide insulation coordination methods for reasonable system design in 22.9kV underground cable system.