• International journal of advanced smart convergence
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• v.8 no.1
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• pp.9-17
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• 2019

In this article, we present a performance enhancement scheme for mobile applications by adopting persistent memory. The proposed scheme supports the deadline guarantee of real-time applications like a video player, and also provides reasonable performances for non-real-time applications. To do so, we analyze the program execution path of mobile software platforms and find two sources of unpredictable time delays that make the deadline-guarantee of real-time applications difficult. The first is the irregular activation of garbage collection in flash storage and the second is the blocking and time-slice based scheduling used in mobile platforms. We resolve these two issues by adopting high performance persistent memory as the storage of real-time applications. By maintaining real-time applications and their data in persistent memory, I/O latency can become predictable because persistent memory does not need garbage collection. Also, we present a new scheduler that exclusively allocates a processor core to a real-time application. Although processor cycles can be wasted while a real-time application performs I/O, we depict that the processor utilization is not degraded significantly due to the acceleration of I/O by adopting persistent memory. Simulation experiments show that the proposed scheme improves the deadline misses of real-time applications by 90% in comparison with the legacy I/O scheme used in mobile systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.135-158
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• 2018

High-Speed vehicles can be considered as multiple mobile nodes that move together in a large-scale mobile network. High-speed makes the time allowed for a mobile node to complete a handover procedure shorter and more frequently. Hence, several protocols are used to manage the mobility of mobile nodes such as Network Mobility (NEMO). However, there are still some problems such as high handover latency and packet loss. So efficient handover management is needed to meet Quality of Service (QoS) requirements for real-time applications. This paper utilizes the cross-layer seamless handover technique for network mobility presented in cellular networks. It extends this technique to propose QoS-aware NEMO protocol which considers QoS requirements for real-time applications. A novel analytical framework is developed to compare the performance of the proposed protocol with basic NEMO using cost functions for realistic city mobility model. The numerical results show that QoS-aware NEMO protocol improves the performance in terms of handover latency, packet delivery cost, location update cost, and total cost.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.211-214
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• 2005

There are emerging many eScience applications. More and more scientists want to collaborate on their investigation with international partners without space limitation by using these applications. Since these applications have to analyze the massive raw data, scientists need to send and receive the data in short time. So today's network related requirement is high speed networking. The key point of network performance is transport protocol. We can use TCP and UDP as transport protocol but we use TCP due to the data reliability. However, TCP was designed under low bandwidth network, therefore, general TCP, for example Reno, cannot utilize the whole bandwidth of high capacity network. There are several TCP variants to solve TCP problems related to high speed networking. They can be classified into two groups: loss based TCP and delay based TCP. In this paper, I will compare two approaches of TCP variants and propose a hybrid approach for high speed networking.

• The Journal of the Korea Contents Association
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• v.14 no.5
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• pp.8-17
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• 2014

Petascale systems(so called supercomputers) have been mainly used for supporting communication-intensive and tightly-coupled parallel computations based on message passing interfaces such as MPI(HPC: High-Performance Computing). On the other hand, computing paradigms such as High-Throughput Computing(HTC) mainly target compute-intensive (relatively low I/O requirements) applications consisting of many loosely-coupled tasks(there is no communication needed between them). In Korea, recently emerging applications from various scientific fields such as pharmaceutical domain, high-energy physics, and nuclear physics require a very large amount of computing power that cannot be supported by a single type of computing resources. In this paper, we present our HTCaaS(High-Throughput Computing as a Service) which can leverage national distributed computing resources in Korea to support these challenging HTC applications and describe the details of our system architecture, job execution scenario and case studies of various scientific applications.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.420-422
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• 1999

To improve traction effort performance and stability of Korean High-Speed Railway Train, a practical re-adhesion controller including a novel wheel slip protection control scheme is proposed. The presented method is verified by various train running simulations by induction motor vector control with PWM inverter.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.841-843
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• 2006

In high-performance cold work applications, tool failure depends on the predominating loading conditions. Typical failure mechanisms are a combination of abrasive wear, adhesive wear, plastic deformation, cracking and edge crumbling. In this paper we demonstrate how the microstructure of tool steels can be positively influenced by modifying the alloying system and the production route to meet the demands of the different loading situations which occur during operation. The investigation was focused on ductility, fatigue strength and wear resistance. Theoretical considerations were confirmed by practical tests.

• Steel and Composite Structures
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• v.51 no.6
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• pp.619-645
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• 2024

In the construction industry, composite structures have revolutionized traditional design principles, opening innovative possibilities. The Concrete Encased - Concrete Filled Steel Tubular (CE-CFST) column stands out as a distinctive composite structure, offering structural stability and resilience for various engineering applications. Comprising Reinforced Concrete (RC) and Concrete Filled Steel Tubular (CFST) components, CE-CFST columns are valued for their inherent properties, including ductility and rigidity, CE-CFST is commonly used in the construction of bridges, high-rise buildings, and more. This article aims to provide a concise overview of the evolutionary development of CE-CFST columns and their performance in structural applications. Through a comprehensive review, the study delves into the behaviour of CE-CFST columns under different scenarios. It examines the influences of key parameters such as size, infills, cross section, failure causes, and design codes on the performance of CE-CFST columns, highlighting their enhanced functionality and future potential. Moreover, the review meticulously examines previous applications of CE-CFST columns, offering insights into their practical implementation.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.27-27
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• 2000

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.11
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• pp.97-104
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• 2010

This paper presents a high performance 32-bit single core AES architecture. The proposed architecture employs a 5-stage pipeline: four stages in the ShiftRows/InvShiftRows module, and one stage in the MixColumn/InvMixColumn module. Circuit size reduction has been achieved through merging of the shift rows and inverse shift rows. The mix column and inverse mix column share the same resources. Three 32-bit registers replace the conventional ten 32-bit registers in the RCON architecture. The proposed architecture has been implemented in Verilog HDL, and yields 415 Mbits/s throughput with the circuit size of 13764 gate equivalents on the 0.18um CMOS process technology. This high performance architecture is suitable for wireless network router applications.

• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.78-84
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• 1999

A compact air-preheating type heat exchanger was developed and tested for the ultra-high temperature heat recovery applications. For the direct use of exhaust gases up to $1200^{\circ}C$, the heat exchanger adopted a ceramic core with high strength and low thermal expansion coefficient less than $1{\times}10^{-6}^{\circ}C^{-1}$. The ceramic core was fabricated by special extrusion and bonding techniques. To minimize thermal stresses in the core, spring-loaded sealing mechanism was designed and successfully installed. 1-pass air flow scheme was adopted for the compactness and cost-savings. The pressure test for the ceramic core showed no failure under 35 kPa and less than 3% leak under 7 kPa. Flue gas simulation system was developed to investigate the performance of the heat exchanger. The test results showed normal operations of the heat exchanger up to $1200^{\circ}C$ of exhaust gases and relatively high heat recovery efficiencies of 31～39% depending upon exhaust gas temperatures..