• The Journal of the Korea Contents Association
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• v.12 no.5
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• pp.22-31
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• 2012

A Smartphone is an intelligent device combined mobile phone and pc's support functions, and can perform multiple functions to satisfy the demands of users. It has excellent processing power and communication modules(DMB, Wi-Fi, Bluetooth, NFC etc) to carry out the demands of users. But continuous using of battery power on processor and equipped modules causes acceleration of battery consumption. This means that effective power management in devices like smartphone is important. Therefore, the management of power consumption on system execution and communication module is a serious issue in this field of study. In this paper, we would like to propose a communication module selection algorithm based on energy consumption parameter of each communication module and data transfer time. Our scheme automatically select appropriate communication system to reduce high energy consumption on bluetooth sleep mode so that this scheme is more efficient and effective thus improving user convenience in longer usage time. Experimental results showed the 20% energy saving.

• Tunnel and Underground Space
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• v.24 no.1
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• pp.55-66
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• 2014

In this study, a joint survey system was developed to efficiently analyze geometrical characteristics of joint structures in rock mass using photogrammetric technique. The system includes both hardware and software. The hardware consists of a high resolution image camera for photographing image of a surface of rock body, a direction controlling system for adjusting the attitude of camera, and a digital compass for measuring the rotation angle of camera. The software was also developed in order to analyze the orientation, density, mean length of joints revealed on the images of rock surfaces. The software developed in this study was named as JointeXtractor. As applying this system into several field measurements, the orientation, density, mean length of joints could be quantitatively measured through analyzing the images of rock surfaces, in which the case of a difficult-to-access area was especially included for the test of the system.

• Explosives and Blasting
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• v.31 no.1
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• pp.41-48
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• 2013

Progressive collapse is generally defined as a local failure of structural members occurring due to abnormal load which results in the partial collapse or total collapse of a structure. Unlike progressive collapse, explosive demolition is a method of inducing the total collapse of structure by removing all or portion of structural members. In explosive demolition the partial collapse of the structural members can be controlled at appropriate time intervals by blasting, to induce the progressive collapse of the structure and control the collapse behavior. In this study, a nonlinear dynamic analysis was carried out in order to apply the progressive collapse process to explosive demolition design of the RC structure. The occurrence of progressive collapse of analytical models was examined according to the number of floors, the removed column height and span length. For models that resisted progressive collapse, progressive collapse resisting capacity was evaluated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1443-1453
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• 1998

This paper presents the speech synthesis engine that converts the character strings kept in a computer memory into the synthesized speech sounds with enhancing the intelligibility and the naturalness by adapting the waveform processing method. The speech engine using demisyllable speech segments receives command streams for pitch modification, duration and energy control. The command based engine isolates the high level processing of text normalization, letter-to-sound and the lexical analysis and the low level processing of signal filtering and pitch processing. The TTS(Text-to-Speech) system implemented by using the speech synthesis engine has three independent object modules of the Text-Normalizer, the Commander and the said Speech Synthesis Engine those of which are easily replaced by other compatible modules. The architecture separating the high level and the low level processing has the advantage of the expandibility and the portability because of the mix-and-match nature.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.4
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• pp.47-55
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• 2009

The purpose of this study is to verify the transfer function of input acceleration and output control force by linearizing a velocity-dependent damping term of Liquid Column Vibration Absorber (LCVA). Analytical and experimental research is conducted to identify natural frequency, damping ratio and participated mass ratio of LCVA with various section ratios of vertical and horizontal areas. Findings obtained experimentally by the shaking table test are compared with analytical findings using optimization technique with constraints. The results indicate that the level of liquid and section ratio of LCVA affect the characteristics of damping ratio and mass ratio. Damping and mass ratio increase as the section of vertical column of LCVA decreases, due to turbulence in the elbow of LCVA.

• Journal of the Korea Society of Computer and Information
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• v.12 no.1 s.45
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• pp.107-116
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• 2007

Is need Remote Access through internet for business of Ubiquitous Computing age, and apply OTP for confidentiality about inputed ID and Password, network security of integrity. Current OTP must be possessing hardware of Token, and there is limitation in security. Install a Snooping tool to OTP network in this treatise, and because using Cain, enforce ARP Cache poisoning attack and confirm limitation by Snooping about user password. Wish to propose new system that can apply Tokenless OTP by new security way, and secure confidentiality and integrity. Do test for access control inflecting Tokenless OTP at Remote Access from outside, and could worm and do interface control with certification system in hundred. Even if encounter hacking at certification process, thing that connection is impossible without pin number that only user knows confirmed. Because becoming defense about outward flow and misuse and hacking of password when apply this result Tokenless OTP, solidify security, and evaluated by security system that heighten safety.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.767-771
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• 2012

남강댐은 평지에 위치하여 댐 높이가 낮고 댐운영 수위의 편차가 작기 때문에 계획홍수위 아래 완경사 비탈면이 갈수기인 3월부터 5월 사이에 장기간 노출되어 5월 전후에 발아하는 식생 특히, 버들류가 이입, 성장하여 대규모 군락을 이루고 있다. 현재 형성된 대규모의 버들류 군락은 댐수질을 악화시킬 뿐만 아니라 자기솎음질(self-thinning)에 의해 고사한 버들류의 유목으로 인하여 댐운영에 많은 애로를 초래하고 있다. 본 연구에서는 버들류 군락 형성과 댐운영수위와의 상관관계를 도출하여 버들류를 적절하게 제어할 수 있는 댐운영 방안을 마련하기 위한 기초자료로 활용하고자 하였다. 따라서, 버들류의 이입시점을 명확히 파악하기 위하여 현재의 남강댐 건설 직후인 1979년, 2003년 2010년의 항공사진과 수심측량에 의한 지형도를 이용하여 버들류 군락의 확장 경향을 분석하였다. 또한, 버들류의 이입시점을 명확히 파악하기 위하여 방형구를 설치하여 버들류의 밀도 및 흉고직경을 조사하고, 성장추에 의한 수령을 조사, 분석하였다. 연구결과를 요약하면 다음과 같다. 남강댐 연안대에 분포하는 버들류는 총 17종이며, 출현빈도가 높은 종은 선버들(Salix nipponica), 버드나무(Salix nipponica), 왕버들(Salix gracilistyla), 등으로서 선버들(Salix nipponica)이 우점종인 것으로 조사되었다. 남강댐 연안대에 분포하는 버들류의 수령을 조사한 결과 수령은 약 9년~10년, 흉고직경 10~15cm, 수고 7~8m인 것으로 조사되었다. 댐운영수위와 버들류의 수령을 분석한 결과 2002년 5월 댐수위 38.5~41.0m 일 때 연안대의 수면부근에서 1단계로 이입, 정착한 것으로 보이며, 2004년 및 2005년 5월경에 댐수위 36m일 때 2단계로 이입, 정착하여 현재 대규모 군락을 형성한 것으로 추정된다. 남강댐 버들류 군락의 형성은 버들류의 발아기에 댐수위 부근의 습지에서 발아환경이 최적인 온도와 저토환경에서 일시에 이입, 성장한 것으로 보인다. 따라서, 남강댐과 같이 평야부에 위치한 댐에서 댐운영 및 댐수질에 영향을 미치는 버들류를 제어하기 위해서는 버들류의 발아기에 댐운영 수위를 최대한 높여 현재의 버들류 군락에 의하여 발아, 성장이 불가능하도록 하거나 아니면 댐운영 수위를 낮추어 발아해도 홍수기 동안 장기간의 침수에 의하여 고사되도록 하는 댐운영 방안을 마련해야 할 것이다.

• Plant Journal
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• v.17 no.1
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• pp.38-49
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• 2021

In order to increase power plant efficiency, the steam temperature was increased to 610 ℃ which deteriorates the durability of the boiler tube and as the use of low-calorie coal increases the post combustion and delayed combustion phenomenon, the overheating of the final reheater and the tube rupture are becoming frequent. In order to prevent overheating of the final reheater, desuperheater water injection was increased, leading to a decrease in boiler efficiency. In this study install a baffle plate at the back of some overheated tube groups, thereby reduce the temperature of the tube by reducing the amount of combustion gas, and the reduced combustion gas moves to an adjacent place to increase the temperature of other tubes. As a result of the study, the temperature deviation between tubes decreased 1.5. And the heat-reducing injection amount was reduced to 6,929 kg/h and the maximum tube temperature was reduced to 623.4℃ which is 6.6℃ more below than the control standard of 630℃.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6A
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• pp.1033-1039
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• 2006

The purpose of this study are to evaluated bond, flexural properties and control of plastic shrinkage cracking of crimped type synthetic fiber with amplitude 6 mm and height 1.8 mm reinforced cement based composites. Bond and flexural test were conducted in accordance with the JCI-SF 8 and JCI SF-4 standard, respectively. The plastic shrinkage cracking test was conducted for evaluating the effect of fiber in reducing shrinkage cracking in cement based composites. Test results indicated that the crimped typel synthetic fibers performed significantly better than the straight type fiber in terms of interface toughness and pullout load and the crimped type synthetic fibers improved the flexural toughness of concrete. Also, the increasing the crimped type synthetic fiber volume fraction from 0.00% to 1.00% improved the plastic shrinkage cracking resistance. Specially, the effect of control of plastic shrinkage cracking is excellent at the more than 0.5% fibre volume fraction.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.214-214
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• 2022

감포댐은 2006년 준공하여 각종 시설 및 설비의 노후화가 진행중에 있으며, 최근 감포댐 인근 지역에서 발생한 경주지진(규모 5.8) 및 포항지진(규모 5.4)이 발생하여 지진시 시설물의 안전성에 대해 중요성이 대두되고 있었다. 이에 감포댐 안전성강화 사업을 추진하게 되었고, 주요 사업내용은 취수탑 관리교 내진보강, 댐체 심벽보강을 통한 댐체 안전성확보, 비상방류시설 개선이다. 취수탑 관리교는 교각단면의 변위연성도 및 교량받침에 의한 구조물 안전성 평가를 시행하였고, 단면강도는 모멘트-곡률해석법에서 탄성영역의 단면강도 대비 탄성지진력을 비교하여 안전성을 검토하였다. 검토결과 교량받침의 내진성능은 부족한 것으로 검토되어 유량제어형 멀티펌프와 안전잭을 이용한 변위제어 방식의 교량동시 인상공법이 가능하고 인상정밀도 ±0.5mm이내의 성능을 가진 교량인상공법 적용하여 보강을 하는 것으로 계획하였다. 댐체 심벽보강을 위해 먼저 전기비저항탐사를 수행하여 전기비저항대를 탐사하여 심벽부에서 포화대가 형성된 부위를 조사하였다. 그리고 댐 상·하류에 전극을 설치하고 전류를 발생시켜 측정 지점별 자기장을 측정을 통하여 댐체내 침투에 따른 유로 형성여부 파악을 위한 전자기장탐사를 시행하였다. 마지막으로 심벽 시추조사를 시행하여 공내수를 조사하였다. 조사결과 포화대의 위치 및 이상대가 다양한 것으로 나타났으며, 이는 불특정 지점에 연약대가 존재한다 판단하여 심벽부 보강계획을 전반적으로 적용하는 것으로 결정하였다. 비상방류시설은 최근 15년 실측자료의 홍수기(6~9월) 평균유입량을 적용하여 검토하였으며 검토결과 배제대상 높이 75%까지는 3.7일, 완전배제까지는 11.2일이 걸려 댐설계기준을 충족하는 것으로 검토되다. 다만 감포댐 비상방류시설이 하천제방과 직각방향으로 형성되어 있고, 하천의 폭이 좁아 과거 방류시에도 제방을 월류하는 것으로 조사되어 하천의 세굴을 방지하고 제방 안전성을 확보하기 위하여 비상방류시설에 감세공을 설치하고, 제방에 디플렉터 옹벽을 설치하는 것으로 계획하였다. 감세공은 2번에 걸친 감세효과로 방류시 하류바닥 및 옹벽 보호 효과가 큰 미국 USBR의 TypeVI를 적용하였으며, Flow-3D 모델링을 통하여 제방에 월류가 발생하지 않는 최적의 대안 옹벽규모를 산정하였다.