• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.277-285
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• 2007

The adsorption characteristics of multi-component solvent vapors including poorly-adsorbable chemicals such as toluene-xylene-MEK and toluene-MEK-IPA on the activated carbonaceous adsorbents were investigated in a stainless steel fixed bed of 10.2 cm ID and 50 cm in height in order to identify those carbons for eliminating and recovering solvent vapors from industrial emission sources. The used activated carbonaceous adsorbents were pelletized commercial activated carbons and activated carbon fiber. Breakthrough curves and adsorption capacity at atmospheric pressures were obtained. It has been found that non-polar and larger molecules have been adsorbed better than polar and smaller molecules. In special, alcohols and ketones were poorly adsorbed caused by competitive adsorbability in multi-component mixture system. However, it could be overcome by profitable employment of organization of cooperative system which was composed of different porosity activated carbonaceous adsorbents appropriately.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.1
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• pp.1-13
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• 1994

Procedures for the development of a preswirl stator-propulsion system for a VLCC 300K are described in this paper. The preswirl stator-propulsion system is one of the compound propulsor systems, which is used for the purpose of recovering propeller slipstream rotational energy by locating a stator in front of the propeller. The preswirl stator-propulsion system can be considered as a most reliable energy saving device because of its simple mechanism. Five stators are designed for the existing hull form and propeller, and their effects are verified by model tests. Open-water test result of the preswirl stator-propulsion system at the cavitation tunnel show $4{\sim}6%$ increase of open-water efficiency compared to that of a propeller without stators. Maximum 6.5% decrease of delivered power at the design speed(15.5knots) is expected with the designed stator based on the analysis results of resistance and self-propulsion test at the towing tank.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.3
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• pp.243-248
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• 2013

Internal combustion engines typically expel 30%-40% of the energy supplied by fuel to the environment through their exhaust system. Therefore, further significant improvements in the thermal efficiency of IC engines are possible by recovering the waste heat from the engine exhaust gas. With this fact in mind, a numerical simulation was carried out to investigate the potential of using thermoelectric generation with an internal combustion engine for waste heat recovery. Physical parameters such as the exhaust temperature and mass flow rate were evaluated in the exhaust system, and the optimum location for inserting a thermoelectric generator (TEG) into the system was determined. The TEG will be located in the exhaust system and will use the energy flow between the warmer exhaust gas and the external environment. The optimum position of the temperature distribution and the TEG performance were predicted through numerical analysis. The experimental results obtained showed that the power output significantly increases with the temperature difference between the cold and hot sides of the TEG.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1100-1105
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• 2017

In this paper, we propose a power control technique for D2D communication in the heterogenous network consisting of cellular and D2D communication systems. Although the transmit signal of D2D communication degrades the performance of cellular system by interfering the signal reception at CU in the conventional heterogenous networks without eavesdroppers, it can be utilized as jamming signal for preventing other devices from recovering the transmitted information if there are eavesdroppers in the network. The proposed power control technique maximizes the achievable rate of D2D communication while ensuring the target security performance of cellular communication system. Through simulation results, we validate the analysis results and compare the performance with the conventional D2D communication scheme that utilizes its full transmit power for maximizing the achievable rate regardless of the performance of cellular system.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.332-338
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• 2017

Launch and recovery system(LARS) is required to perform an USV-based underwater exploration. Through the analysis of the requirements according to the scenario of underwater exploration, the mechanism of LARS and the conceptual design of the mechanical parts of LARS are carried out. In addition, a USV motion can be induced due to environmental disturbances such as waves, so the detailed design of LARS for recovering the underwater tow-fish stably in consideration of the USV motion is performed. To verify the performance of launch and recovery operations, LARS and test bed were developed. The results show that the proposed LARS can stably launch and recovery an underwater tow-fish.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1B
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• pp.90-98
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• 2002

To increase system capacity in WCDMA receiver, the coherent detection is an essential technology for recovering transmitted symbols correctly. For coherent detection, an accurate and fast channel estimation is required. In next generation mobile communication system, high frequency carriers are used, and high data rate services are provided for subscribers having high mobility. In this communication environment, however, the rapidly-changing doppler frequency degrades the quality of the transmitted signal a lot. In WCDMA system, the channel estimation is conducted using pilot channel and/or pilot symbols which are known to both transmitter and receiver. Some existing channel estimation algorithms utilize these information quite well, but the performance of channel estimation gets very poor in a complicated fading channel distorted by the doppler effect. In this paper, we propose a new channel estimation algorithm combining an early-late doppler compensator so that the doppler effect and the fading characteristics are compensated at the same time. By computer simulation, the proposed algorithm proved to be a much more efficient channel estimation method in the fast fading channel, even at reasonably low Eb/No.

• Journal of the Korea Society of Computer and Information
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• v.19 no.8
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• pp.129-137
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• 2014

The patients who have illness of hand and upper limb should be received rehabilitation treatment to recover such illness. The rehabilitation treatments is a treatments designed to facilitate the process of recovery from injury, illness, or disease to as normal a condition as possible. This should be done continuously and repeatedly. In this paper, we describe hand-rehabilitation system which provides a treatment method improving and recovering the function of injured hands. Expecially, this system is using a leap motion device which can easily and properly identify and trace a hand motion and provide six treatment patterns for hand rehabilitation. By using this system, the patients can do rehabilitation treatment easily and continuously in their daily life and in result, the achievement of treatment will be improved.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.664-665
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• 2016

This paper proposes an identification system based on QR (Quick Response) code for production and disposal information of Internet of Things (IoT) devices. Three thousands and five hundreds of electronic devices have replaced and discarded in South Korea in a year, and twenty millions to fifty millions tons of e-wastes have happened throughout the world every year. According to Gartner, market research institution, the number of IoT devices will increase from 2.3 billions in 2013 to 30 billions in 2020, however, the regulations and systems which take into account environment were not prepared. The identification systems for reflecting information of devices, which are produced or discarded, are required to resolve the problem. The proposed identification system based on QR code can store much more massive data such as the producer, product's model, serial number, recycling rate, recovering rate, recyclability rate, recoverability rate than RFID (Radio-Frequency Identification). Also, users can immediately recognize production and disposal information by a QR code application in a smartphone.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.4
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• pp.247-258
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• 2009

Distributed file systems running on a cluster of inexpensive commodity hardware are being recognized as an effective solution to support the explosive growth of storage demand in large-scale Internet service companies. This paper presents the design and implementation of BeanFS, a distributed file system for large-scale e-mail services. BeanFS is adapted to e-mail services as follows. First, the volume-based replication scheme alleviates the metadata management overhead of the central metadata server in dealing with a very large number of small files. Second, BeanFS employs a light-weighted consistency maintenance protocol tailored to simple access patterns of e-mail message. Third, transient and permanent failures are treated separately and recovering from transient failures is done quickly and has less overhead.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.4
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• pp.324-335
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• 2001

Information systems, which support information security functions such as CALS and EC systems, should have cryptographic functions for information in order to storage and communicate securely. Additionally, including recovery of lost keys, lots of cryptographic keys should be securely managed. In this paper, we present some results of development of a key recovery system for recovery of encrypted data. The proposed system, in a type of key encapsulation approach, confirms to NIST's RKRP(Requirements for Key Recovery Products) that is a defecto international key recovery standard, as well as CC 2.0 that is a international security evaluation criteria. A message sender secretly choices two or more key recovery agents from a pool of key recovery agents. The key recovery information is generated by using the recovering key, random keys and public keys of the chosen agents. A message receiver can not know which key recovery agents are involved in his key recovery service. We have developed two versions of prototype of key recovery system such as C/Unix and Java/NT versions. Our systems can be used for recovery of communicating informations as well as storing informations, and as a new security service solution for electronic commerce service infrastructures.