• 국제물리치료학회지
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• 제7권2호
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• pp.994-998
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• 2016

The purpose of this study was to examine the effects of sensory stimulation type on the learning of the elderly. The study implemented elderly verbal learning test by evenly dividing a total of 40 elderly people into auditory stimulation followed by visual stimulation group(AVG), visual stimulation followed by auditory stimulation group(VAG), simultaneous visual and auditory stimulation group(SG), and auditory stimulation group(AG). The result are as follows. SSG showed highest results in most of the test, followed by AVG, VAG, and AG. In particular, SG showed a statistically significant difference in immediate recall total score and short delay free recall score(p<.05). In the post-hoc test results of immediate recall total score, SG showed highest score with a statistical significance. AVG showed the second highest score, followed by VAG and AG and all showed a statistic significance(p<.05).In the post-hoc test results of short delay free recall score, SG and AVG showed a statistically significantly higher score than AG(p<.05). The results suggest that simultaneous stimulation of visual and auditory sense is more effective for improving the learning of the elderly people than visual stimulation followed by auditory stimulation or auditory stimulation followed by visual stimulation.

• 천문학회보
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• 제41권2호
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• pp.36.2-36.2
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• 2016

In mm-VLBI, the quality of observation data is largely affected by atmospheric effect. The most challenging matter is that the phase of correlator output fluctuates rapidly resulting from a variation of atmospheric propagation delay. Consequently, it is demanding to achieve high Signal-to-Noise ratio by integrating data in time domain before calibrating atmospheric delay. However, Korean VLBI Network (KVN) has a unique system to make a 4-frequency (22/43/86/129 GHz) simultaneous observation in mm-wavelength and Frequency Phase Transfer (FPT) calibration technique has effectively removed atmospheric delay in the simultaneous multi-frequency observation of the KVN. For astrometric and astrophysical studies, we evaluated the FPT performance of KVN in various observing conditions. Using the total 38 bright AGNs, we have compared atmospheric conditions such as ground-based weather information, system temperature, atmospheric delay with the calibration results of FPT at 22/43/86/129 GHz during the five experiments in 2013, and quantified its performance in terms of coherence function and Allan variance. We present the analysis result of the relation between the FPT performance and observing conditions.

• 한국항행학회논문지
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• 제19권1호
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• pp.53-59
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• 2015

노드들 간의 설치비용과 트래픽 요구량이 주어졌을 때, 이 조건을 만족하는 메쉬망을 설계하는 주요 고려사항으로는 설계시간, 비용, 지연, 신뢰성등 여러 가지가 있으며, 일반적으로 설계시간을 줄이고, 비용은 작게, 지연은 적게, 신뢰성이 높은 메쉬망을 설계하여야 한다. 설계시간에 대한 문제는 Aaron Kershenbaum이 제안한 MENTOR (mesh network topology optimization and routing) 알고리즘에 의해 최소화를 이루는데 성공하였지만 비용, 지연, 신뢰성에는 여전히 문제가 남아있다. 본 논문에서는 MENTOR의 설계시간의 장점을 유지하면서 다른 성능인자들을 만족시킬 수 있는 새로운 망설계 알고리즘을 제안하고자 한다. 제안된 알고리즘의 설계결과는 MENTOR 알고리즘의 성능인자들보다 개선되었음을 보여주었다.

• 한국통신학회논문지
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• 제25권5A호
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• pp.593-601
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• 2000

다중 대역 확산 CDMA 시스템에서 확산 대역폭과 레일리 페이딩 채널의 지연 확산에 대한 다중 선택 결합 RAKE 수신기의 성능을 분석하여, 지연 확산이 다른 여러 채널 환경에서 RAKE 수신기 차수에 따른 전체 수신 에너지와 다중 경로 다이버시티 이득간의 상호 관계를 규명하였다. 분석 결과, 지역 확산이 작은 환경에서의 광대역 확산을 이용하여 확산 대역폭을 증가시키는 것이 더 좋은 성능을 나타냈다. 높은 차수와 낮은 차수의 선택 결합기간의 성능 비교 결과, 확산 대역폭이 증가할수록 그 성능 차가 더 크게 나타났다. 또한, 확산 대역폭을 일정수준 이상으로 증가시킬 경우 수신 성능이 저하되었으며, 각 채널 환경에서의 최적 확산 대역폭은 채널의 지연 확산이 증가할수록 감소하였다.

• 한국항공운항학회지
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• 제28권1호
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• pp.7-13
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• 2020

A significant growth in local air traffic volume is leading to airway congestion and flight delays especially for Incheon-China and Incheon-Europe sectors. A key method to increase the airway capacity is to place a supplemental airway parallel to the existing one and in cooperation between the aviation authorities between China and Korea, a dual airway track was implemented on December 6, 2018. Here, we use airline A's flight data to analyze the congestion change effect of the new airway. Results show total delay time to Europe is reduced 51% (13.4 to 6.6 minutes) as the delay distribution for 16-30 minutes, 31 minutes and greater decreased from 23.2% to 8.2% and 8.7% to 1.0% respectively. The delay to China also decreased but the drop is not as significant as flights to Europe. This is caused by the difference in flight distance, traffic volume, and characteristics of flights landing and transiting China. Flights to Europe show a broad distribution in altitude allocation and reduction in aircraft separation demonstrating the effectiveness of a dual airway track.

• 대한전자공학회논문지SD
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• 제41권10호
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• pp.63-68
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• 2004

칩의 외부 클럭과 내부 클럭 사이의 스큐를 줄이기 위하여 고정밀도 동기 미러 지연 소자를 제안한다. 제안하는 동기 미러 지연 소자는 두 단계에 걸쳐서 클럭 스큐를 감소시킨다. 먼저 기존의 동기 미러 지연 소자에 의하여 동기화가 이루어진다. 그 다음, 연속 근사 레지스터에 의하여 조절되는 delay-locked loop에 의하여 세밀하게 동기화가 이루어진다. 동기화가 이루어지는데 필요한 전체 시간은 10 사이클이다. 모의 실험 결과, 제안하는 동기 미러 지연 소자는 182MHz에서 50psec의 스큐 특성을 가지며, 0.35㎛ 1-poly 4-metal CMOS 공정 하에서 3.3V의 전원 전압을 사용했을 때, 17.5mW를 소모하는 것을 알 수 있다.

• 전기전자학회논문지
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• 제24권1호
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• pp.326-332
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• 2020

본 논문은 듀티사이클 기반의 무선센서네트워크에서 에너지 효율성을 높이고 시간 지연을 줄일 수 있는 경로설정을 위해 새로운 라우팅 메트릭을 고안하고 이를 활용한 라우팅 프로토콜을 제안한다. 듀티사이클을 고려한 새로운 라우팅 메트릭인 EDW 메트릭을 사용함으로써 에너지 효율적이며 저지연의 경로를 설정할 수 있다. 본 논문에서는 새로운 라우팅 메트릭을 적용하는 크로스레이어 기반의 다중경로 라우팅 프로토콜을 제안하고 실험을 통해 낮은 전송 지연시간과 적은 에너지소비를 확인하였다.

• 화약ㆍ발파
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• 제13권1호
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• pp.20-31
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• 1995

Many methods and techniques to reduce ground vibrations are well known. Some of them are to adopt electric milisecond detonators with a sequential blasting machine or an initiating system with an adequate number of delay intervals. The types of electric detonators munufactured in Korea include instantaneous, decisecond and milisecond delays byt numbers of delay intervals are only limite from No.1 to No.20 respectively. It is not sufficient to control accurately milisecond time with these detonators in tunnel excavation. Sequential fire time refers to adding an external time delay to a detonators norminal firing time to obtain sequential initiation and it is determined by sequential timer setting. To reduce the vibration level, sequential blasting machine with decisecond detonatore was adopted. A total of 134 blasting was recorded at various sites. Blast-to-structure distances ranged from 20.3 to 42.0 meter, where charge weight varied from 0.25 to 0.75 kg per delay. The results can be summarized as follow : 1. The effects of sequential blasting machine on the vibration level are discussed. The vibration level by S.B.M. are decreased approximately 14.38~18.05 to compare to level of conventional blasting and cycle time per round can be saved. 2. The empirical equations of particle velocity were obtained in S,B.M. and conventional blastin. $V=K(D/W^{1/3})-n$. where the values for n and k are estimated to be 1.665 to 1.710 and 93.59 to 137 respectively. 3. The growth of cracks due to vibrations are found but the level fall to within allowable value.

• 전기학회논문지
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• 제67권12호
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• pp.1587-1594
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• 2018

In south korea, the government make a plan to generate the 20% of the total electrical power as renewable source like wind generation and solar generation. This plan will accelerate the increase of fault current with power industry's growth. As the increase of fault current, the superconducting fault current limiter (SFCL) has been studied. In case that the SFCL is applied in power system, it can cause the overcurrent relay (OCR)'s trip delay because of the reduced fault current. In this paper, the overcurrent relay with voltage component was suggested to improve the OCR's trip delay caused by the SFCL and compensational constant was introduced to have the trip time similar to the trip time of case without the SFCL. For conforming the effect of the suggested OCR with voltage component, the PSCAD/EMTDC simulation modeling and analysis were conducted. Through the simulation, it was conformed that the trip delay could be improved by using the suggested OCR and compensational constant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권11호
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• pp.5269-5286
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• 2018

Task scheduling is one of the key issues in improving system performance and optimizing resource management in cloud computing environment. In order to provide appropriate services for heterogeneous users, we propose a novel task scheduling strategy with service differentiation, in which the delay sensitive tasks are assigned to the rapid cloud with high-speed processing, whereas the fault sensitive tasks are assigned to the reliable cloud with service restoration. Considering that a user can receive service from either local SaaS (Software as a Service) servers or public IaaS (Infrastructure as a Service) cloud, we establish a hybrid queueing network based system model. With the assumption of Poisson arriving process, we analyze the system model in steady state. Moreover, we derive the performance measures in terms of average response time of the delay sensitive tasks and utilization of VMs (Virtual Machines) in reliable cloud. We provide experimental results to validate the proposed strategy and the system model. Furthermore, we investigate the Nash equilibrium behavior and the social optimization behavior of the delay sensitive tasks. Finally, we carry out an improved intelligent searching algorithm to obtain the optimal arrival rate of total tasks and present a pricing policy for the delay sensitive tasks.