• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.90-94
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• 2003

For the structure of VMS is required to the maritime MDT for realtime acquisition the position reporting of navigating ships. The first study is the recording method a navigating data by GPS, the 2th is SSB modem for data trans-receiver by use ship. And then the communication protocol of automatic traffic for in continues transmission a ship's ID, time and position data of GPS. In this paper have studied the SSB modem for transmission the voice and data at same time. Which is adapted to the communication control unit, protocol of data traffic and acquisition, displayer of character data. This maritime GPS MDT is considered to low-cost type by using microprocessor.

• The Transactions of the Korea Information Processing Society
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• v.13 no.10
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• pp.475-480
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• 2024

As Internet of Things (IoT) technology is being used in all industries, the importance of secure and convenient firmware update technology is increasing. However, conventional FOTA (Firmware Over-The-Air) technology has a problem because the security is weak when updating firmware with a single path, and strong encryption technology cannot be utilized. Therefore, this study proposes a secure FOTA (S-FOTA) mechanism for lightweight IoT and adaptive S-FOTA ARQ (Automatic Repeat Request) mechanism. This adaptive S-FOTA ARQ mechanism considers the case where the original file cannot be recovered because of the increase in lost files due to the congested channel state and compares and analyzes the conventional method in terms of security, complexity, and transmission speed. Experimental results show that S-FOTA with 40 encrypted files reduced the attacker's attack success rate by at least 62.58% and up to 99.99%, and S-FOTA with 40% of the total number of encrypted file segments takes at least 996.39% more time on average and up to 3374.99% more time than conventional FOTA. In addition, the transmission speed of the adaptive S-FOTA ARQ mechanism was at least 63.16% and up to 2736.36% higher than that of the conventional S-FOTA, and at least 53.89% and up to 70.89% higher than that of the conventional ARQ mechanism.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.05a
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• pp.60-63
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• 2002

자동 변속기 차량은 여러 가지의 장점을 지니고 있으며, 쉬프트 맵의 특징이 수동 변속기 차량과는 달리 이미 규정된 패턴을 따른다 하지만 킥 다운, 킥 업, 리프트 풋 업 등의 현상이 어느 운전자에게나, 어떤 주행 상황에서나 일괄 적용되고 있기에 불만스러움을 느끼는 운전자가 있을 수 있다. 이에 본 논문에서는 지능형 자동 변속 시스템의 변속 결과에 따른 운전자의 불만 정도를 고려하고 다음 변속에 반영하도록 고안한 만족도 보정 기법을 제안하고자 한다 만족도 평가는 변속이후 운전자의 조작을 관찰하며, 불만족 정도에 따라 최종 쉬프트 선도의 조정을 결정하도록 고안하였으며, 변속 시스템의 변속 결정과 운전자의 스로틀 및 브레이크 조작을 입력으로 한 신경 회로망을 구성하여 학습하였다

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.171-176
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• 2002

This paper is the study on stress analysis of spur gear using a finite element method. Gear drives constitute very important mechanisms in transmitting mechanical power processes compromising several cost effective and engineering advantages. The load transmission occurred by the contacting surfaces arises variable elastic deformations which are being evaluated through finite element analysis. The automatic gear design program is developed to model gear shape precisely. This gear design system developed was used by pre-processor of FEM packages. The distribution of stresses at contacting surfaces was examined when a pair of gear contact.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.816-819
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• 2002

This paper is the study on stress analysis for tooth modification of high speed gear using a finite element method. Gear drives constitute very important mechanisms in transmitting mechanical power processes compromising several cost effective and engineering advantages. The load transmission occurred by the contacting surfaces arises variable elastic deformations which are being evaluated through finite element analysis. The automatic gear design program is developed to model gear shape precisely. This gear design system developed was used by pre-processor of FEM packages. The distribution of stresses at contacting surfaces was examined when gear tooth contacts. And this paper proposes method for the tooth modification after carrying out stress analysis using a finite element method.

• Journal of Astronomy and Space Sciences
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• v.30 no.2
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• pp.113-121
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• 2013

Heumgyeonggaknu is a water-hammering type automatic water clock which was made by Jang Yeong-Sil in 1438. The water clock that is located in Heumgyeonggaknu consists of Suho which is equipped with 2-stage overflow. Constant water wheel power is generated by supplying a fixed amount of water of Suho to Sususang, and this power is transferred to each floor at the same time. The 1st floor rotation wheel of Gasan consists of the operation structure which has the shape of umbrella ribs. The 2nd floor rotation wheel is made so that the 12 hour signal, Gyeong-Jeom signal, and Jujeon constitute a systematic configuration. The 3rd floor rotation wheel is made so that the signal and rotation of Ongnyeo and four gods can be accomplished. Based on the above conceptual design, this paper analyzed the internal signal generation and power transmission of Heumgyeonggaknu.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.4C
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• pp.370-378
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• 2007

The most appropriate low density parity check (LDPC) code for hybrid automatic repeat request (HARQ) system suitable for future multimedia communication systems is presented in this paper. HARQ system with punctured LDPC code is investigated at first. And two transmission schemes with parallel concatenated LDPC code are also presented and their performances are analyzed according to the various values of mean column weight (MCW). As a result, the parallel concatenated LDPC code with the diversity effect of information bit is considered to be more appropriate for HARQ system considering the throughput as well as error performance.

• Journal of ILASS-Korea
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• v.20 no.3
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• pp.156-161
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• 2015

This paper described the effect of dual clutch transmissions on the stability emissions characteristic in a GDI engine at vehicle Inspection and Maintenance(I/M) program. In order to investigate the influence of direct injection gasoline engine with DCT, the experimental apparatus consisted of GDI engine with 4 cylinder, dynamometer and exhaust emissions analyzer. Analyzed emission gas include CO, HC and NOx results that DCT vehicle in the case of NOx, HC in automatic transmission vehicles less than 1/2 level was confirmed to be exhausted. However vehicle specific power increases CO also has increased.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.726-732
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• 2011

Straight absorptive silencers have been designed to reduce the noise level of a centrifugal blower. Three-dimensional boundary element method is used for the design of absorptive silencers which consist of a perforated main pipe and a outer chamber filled with fibrous material. The experimental results show that the absorptive silencer reduces up to 8 dB(A) in the overall sound pressure level of the blower and up to 15 dB at the blade passing frequency. It is also found that the gap between the silencer and the impeller may substantially alter the acoustic performance of the silencers. The transmission loss predicted by the boundary element method follows overall trends of the measured insertion loss. The experiments also show that the impact of the silencers on the aerodynamic performance of the blower is minimum.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.2
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• pp.30-37
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• 2005

A drum clutch which is a main part for the automatic transmission of auto-mobiles has been manufactured by glob threading and machining. The tooth shape of the drum clutch manufactured by machining has lower dimensional accuracy than that by pressing and its machining needs the enormous cost at plant investment. Thus, this study was designed to develop cold forging process and to improve the productivity and dimensional accuracy. In this work, variables affecting dimensional accuracy were first determined, then cold forming process design according to each variables was performed by FE simulation. Optimal process was suggested on the basis of analytical results.