• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.11a
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• pp.107-109
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• 2016

본 논문에서는 4K UHD 입력 영상을 실시간으로 부호화하기 위해 적용되는 GOP 단위 또는 IDR 주기 단위의 병렬 부호화 구조를 지원하도록 R-${\lambda}$ 모델 기반의 율 제어 방법을 개선하는 비트 분배(bit allocation) 방법을 제안한다. GOP 단위 또는 IDR 주기 단위의 병렬 부호화기 내에서 율 제어기를 작동시키는 경우, 계층적 B 구조에서 같은 계층에 있는 프레임 간에는 상호간에 얼마만큼의 비트를 소모 하였는지에 대한 정보를 공유 할 수 없기 때문에 기존의 비트 분배 방식으로는 비트 예산(bit budget) 관리가 불가능하다. 이를 해결하기 위해 본 논문에서는, 기존의 R-${\lambda}$ 모델 기반 율 제어 방법을 개선하여 부호화 순서에 의한 시간 순서 방향의 비트 예산 갱신 기반 비트 분배하던 방식으로부터, GOP 마다 비트를 할당한 후 계층적 B 구조에서의 계층이 깊어지는 방향으로 비트 예산을 갱신하여 비트를 분배하는 방식으로 율 배분 방식을 개선하였다. 실험 결과를 통해 R-${\lambda}$ 모델 기반 율 제어의 기존 비트 분배 방식보다 제안 방법에 의한 목표 비트 율 달성 오차가 감소함을 확인하였다.

• Journal of Convergence for Information Technology
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• v.7 no.5
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• pp.117-122
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• 2017

In a wireless communication system, increasing the channel capacity with a limited frequency is a problem in all frequency bands. Increasing the frequency bandwidth and increasing the output can increase the channel capacity, but sometimes the communication is not possible due to interference noise. If the radio frequency allocation is set to world standardization such as WRC or ITU-R, each country has strict control over regulations. This is because one wireless communication system should not affect other systems. We present the results of a study on scenarios and analysis of radio waves to be installed inside and outside the aircraft without interfering with the wireless LAN.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.78-86
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• 2015

Up-to-date business environment for manufacturers is very complex and rapidly changing. In other words, companies are facing a variety of changes, such as diversifying customer requirements, shortening product life cycles, and switching to small quantity batch production. In this situation, the companies are introducing the concept of JIT (just-in-time) to solve the problem of on-time production and on-time delivery for survival. Though many companies have introduced ERP (enterprise resource planning) systems and MRP (material requirement planning) systems, the performance of these systems seems to fall short of expectations. In this paper, the case study on introducing an APS (advanced planning and scheduling) system based on dispatching rules to a machining company and on finding a method to establish an efficient production schedule is presented. The case company has trouble creating an effective production plan and schedule, even though it is equipped with an MRP-based ERP system. The APS system is applied to CNC (computer numerical control) machines, which are key machines of the case company. The overall progress of this research is as follows. First, we collect and analyze the master data on individual products and processes of the case company in order to build a production scheduling model. Second, we perform a pre-allocation simulation based on dispatching rules in order to calculate the priority of each order. Third, we perform a set of production simulations applying the priority value in order to evaluate production lead time and tardiness of pre-defined dispatching rules. Finally, we select the optimal dispatching rule suitable for work situation of the case company. As a result, an improved production schedule leads to an increase in production and reduced production lead time.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.5
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• pp.37-43
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• 2009

Streaming video service over wireless and mobile communication networks has received significant interests from both academia and industry recently. Specifically, mobile WiMAX (IEEE 802.16e) is capable of providing high data rate and flexible Quality of Service (QoS) mechanisms, supporting mobile streaming very attractive. However, we need to note that streaming videos can be partially deteriorated in their macroblocks and/or slices owing to errors on OFDMA subcarriers, as we consider that compressed video sequence is generally sensitive to the error-prone channel status of the wireless and mobile network. In this paper, we introduce an OFDMA subcarrier-adaptive mobile streaming server based on cross-layer design. This streaming server system is substantially efficient to reduce the deterioration of streaming video transferred on the subcarriers of low power strength without any modifications of the existing schedulers, packet ordering/reassembly, and subcarrier allocation strategies in the base station.

• Journal of Radiation Protection and Research
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• v.43 no.1
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• pp.1-9
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• 2018

Background: In this study, we investigate the image quality of virtual monochromatic images synthesized from dual-energy computed tomography (DECT) at voltages of 80/140 kV and 100/140 kV. Materials and Methods: Virtual monochromatic images of a phantom are synthesized from DECT scans from 40 to 70 keV in steps of 1 keV under the two combinations of tube voltages. The dose allocation of dual-energy (DE) scan is 50% for both low- and high-energy tubes. The virtual monochromatic images are compared to single-energy (SE) images at the same radiation dose. In the DE images, noise is reduced using the 100/140 kV scan at the optimal monochromatic energy. Virtual monochromatic images are reconstructed from 40 to 70 keV in 1-keV increments and analyzed using two quality indexes: noise and contrast-to-noise ratio (CNR). Results and Discussion: The DE scan mode with the 100/140 kV protocol achieved a better maximum CNR compared to the 80/140 kV protocol for various materials, except for adipose and brain. Image noise is reduced with the 100/140 kV protocol. The CNR values of DE with the 100/140 kV protocol is similar to or higher than that of SE at 120 kV at the same radiation dose. Furthermore, the maximum CNR with the 100/140 kV protocol is similar to or higher than that of the SE scan at 120 kV. Conclusion: It was found that the CNR achieved with the 100/140 kV protocol was better than that with the 80/140 kV protocol at optimal monochromatic energies. Virtual monochromatic imaging using the 100/140 kV protocol could be considered for application in breast, brain, lung, liver, and bone CT in accordance with the CNR results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.1068-1071
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• 2017

The turbine exhaust system consists of a turbine flange, heat exchanger, exhaust duct and thrust nozzle. Heat exchanger is used for the launch vehicle because of the advantage of reducing the weight of the helium gas and the storage tank by using the heat exchanger pressurization method compared to the cold gas pressurizing method. Since the gas generator is combusted in fuel-rich condition, the soot is contained in the combustion gas. Hence, the heat exchanger should be designed considering the reduction of the heat exchange efficiency due to the soot effect. In addition, the uncertainty of the heat exchange calculation and the evaluation of the influence of the combustion gas soot on the heat exchange can not be completely calculated, so the design requirements must include a structure that can guarantee and control the temperature of the heat exchanger outlet. In this paper, it is described that the component allocation, the design method considering the manufacture of internal structure, the advantages of new concept of nozzle design.

• Journal of Korea Society of Industrial Information Systems
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• v.5 no.2
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• pp.22-31
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• 2000

The VB5.2 interface of B-lSDN, that is located between an access network and a service node, allows dynamic allocation and release of ATM resources. In this paper, we propose the B-ANCC protocol of the VB5.2 interface to minimize the overall connection setup delay by introducing the access network. The B-ANCC protocol enhances the B-BCC protocol and adopts a parallel interworking function with signaling protocols in the service node. To confirm the correctness of the proposed B-ANCC protocol, we validate it using the automated validation tool, SPIN. We analyze and simulate the sequential interworking model based on the B-BCC protocol and the parallel interworking model based on the B-ANCC protocol, in terms of a connection setup delay and a completion ratio. It is shown that our proposed parallel interworking model with B-ANCC reduces a setup delay and improves a completion ratio compared to the sequential interworking model with B-BCC.

• Korean Journal of Construction Engineering and Management
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• v.14 no.3
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• pp.12-21
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• 2013

Total Project Cost Management System(TPCMS) was introduced with the purpose of increasing the efficiency of cost control for public construction project in 1994. In this paper, general perception of participants of the public construction project on the TPCMS was examined, and the problems in implementing the TPCMS was figured out through expert interviews and survey. Then better ways to implement the system were drawn based on the problems. To effectively manage the cost of public construction project, basically project cost should be estimated accurately in planning stage and managed based on it to have a project complete within the budget. In addition, the cost need to be managed in more systematic ways in terms of data collection and analysis, and the autonomy in managing the project cost given to the project owner needs to be expanded. Most of all, proper budget should be provided to prevent a project from delay through setting the priority of projects and proper budget allocation based on the priority.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.11
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• pp.7690-7697
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• 2015

This study is to reveal structural causal relationship of individual factors influencing association member's substantive payment in the economic view which is a critical factor of project implementation and identify its influence through simulation and actual proof analysis. As the results of analysis, the first, association member's substantive payment is decided to allow for the difference between special price for association members and general price and the profit arising between the time of approval of disposal plan and moving in. The second, on analysis of sensitivity of individual factors influencing association member's substantive payment, floor area ratio applied to project has the biggest influence. Association member's payment is also greatly influenced by the subject of cost allocation for establishing infrastructure in project area. The third, this study set up a structure model based on causal relationship among the factors deciding association member's payment and empirically examined influence and path of influence which the individual factors exercise. The result indicates that control elements and regional characteristic elements influence association member's payment through the medium of plan elements.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.270-281
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• 2003

E-PON supports efficiently the increased Internet data traffic and efficient bandwidth assignment function by which the shared upstream bandwidth in the broadband access networks. In this paper, when different types of incoming sources are mapped into QoS-aware source and Best-Effort(BE) source, we propose the Dual-GPS schedulaer in E-PON that has the characteristics to provide delay and delay-constraint application, and maximizes the bandwidth to best-effort service. When transmit upstream data in E-PON, The proposed scheme supports the control capabilities of delay and delay-variation for required QoS flow through the novel bandwidth assignment scheme. Simulation results show our scheme outperforms the conventional bandwidth allocation scheme in controlling the delay and delay-variation of E-PON system.