• 기술사
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• 제15권2호
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• pp.3-15
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• 1982

The study on prevention measures for vibration and excavation of tunnel for the #3, #4, Seoul Subway. In the Seoul subway tunnel blasting, the drilling pattern and prevention method to seismic vibration are as follows as well as for adaptions of NATM, the supportings of roof and wall holes are arranged with control blasting. 1. The blasting is executed basically using the low velocity explosive such as slurry, Nitrate ammonium explosive, and F-I and F-II explosive for control blasting substituting of existing dynamite. 2. The cut holes are arranged with burn cut pattern and also must be arranged with M/S electrical delay caps substituting of ordinary do]ay caps. 3. Jack leg drills are used in Five Job sites and a jumbo drill in one job site. 4. In performance of safety work and in maintenance of building safety. The drilling length for blasting will not exceed 1.20 meter for round so that the vibration value shall carry below 0.3cm/sec. The harmonizing of better powder, better drilling machine and better technique is only the way of improving tunnelling efficiency and less vibration will help the dereasing of accidence.

• ETRI Journal
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• 제28권5호
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• pp.680-683
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• 2006

One objective in developing the next generation of wireless communication systems is to increase data rates and reliability. A promising way to achieve this is to combine multiple-input and multiple-output signal processing with a space-time coding scheme, which offers higher coding and diversity gains and improves the spectrum efficiency and reliability of a wireless communication system. It is noted, however, that time delay differences and phase differences among different channels increase symbol interference and degrade system performance. In this letter, we investigate phase differences and their effects on multiple-input and multiple-output systems, and propose a compensation algorithm for the Rayleigh fading model to minimize their effects.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 ICEIC The International Conference on Electronics Informations and Communications
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• pp.97-102
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• 2004

The very complicated proplem in spatial processing is effects of phading (Multipath and Delay Spread) and co-channel interference (CCI). The phading is one of principal causes, that form inter-symbol interference (ISI). Spatial-Temproral Adaptive Filter (STAF) has been taken as a solution of this problem, because it can suppress both these types of interference. But the performance of STAF exposes some elemental limitations, in which are the slow convergence of adaptive process and computational complexity. The cause of this is that, STAF must treat a large quantity of information in both space and time. The way that master these limitation is a use of Subband Spatial-Temproral Adaptive Filter (SSTAF). SSTAF reduce computational complexity by pruning off samples of signal and thus it lost some information in time. This draw on attennation of output SINR of SSTAF. The article analyse a optimal solution of this problem by introducing SSTAF with nonuniform weighted distribution.

• 한국컴퓨터정보학회논문지
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• 제20권10호
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• pp.53-59
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• 2015

In this paper we propose a resource management scheme which allocates hierarchical resources stepwise based on the users' QoS requirement of each service in the macro-femtocell overlaid LTE-Advanced network. Our proposed scheme adjusts the transmission rate to the minimum which guarantees the allowable minimum requirement of delay for each user service. In this way it minimizes the interference on the adjacent channels and it is able to increase the resource utilization efficiency. Simulation results show that our scheme provides better performances than the conventional one in respect of the outage probability and data transmission throughput.

• 한국정밀공학회지
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• 제31권3호
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• pp.243-251
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• 2014

In inference fit assembly process of the industrial robot, it basically needs the force data. One of the typical methods to get the force data is attaching torque sensors on the robot arm joint or end effector. This is effective way to reduce time delay and to improve preciseness of force control, but this method has several problems. To solve that problem, this paper suggests method which measures assembly force without torque sensor by using the sliding perturbation observer(SPO) and assembly process based on SPO to assemble successfully in inference assembly

• Journal of Positioning, Navigation, and Timing
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• 제10권2호
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• pp.83-89
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• 2021

The extended Kalman filter (EKF) is widely used for global navigation satellite system (GNSS) applications. It is difficult to obtain precise positions with an EKF one-way (forward or backward) filter. In this paper, we propose an EKF smoother to improve the positioning accuracy by integrating forward and backward filters. For the EKF smoother experiment, we performed PPP using GNSS data received at the DAEJ reference station for a month. The effectiveness of the proposed approach is validated with multi-GNSS kinematic PPP experiments. The EKF smoother showed 35%, 6%, and 22% improvement in east, north, and up directions, respectively. In addition, accurate tropospheric zenith total delay (ZTD) values were calculated by a smoother. Therefore, the results from EKF smoother demonstrate that better accuracy of position can be achieved.

• 한국정보통신학회논문지
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• 제15권8호
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• pp.1735-1742
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• 2011

최근 대용량의 USB 장치가 휴대하기 편리해지면서 USB 장치의 기능성 또한 빠르게 발전하고 있다. 그러나, USB 장치에 저장되어 있는 개인정보는 별도의 사용자 인증 과정없이 악의적인 목적으로 사용되어 개인정보가 노출될 수 있는 문제가 있다. 이 논문에서는 USB에 저장되어 있는 사용자의 개인정보를 추가 인증 정보 없이 안전하게 보호하기 위한 OTP(One-Time Password)기반의 USB 인증 프로토콜을 제안한다. 제안된 OTP 기반의 USB 인증프로토콜은 일방향 해쉬 함수를 사용하여 단순한 동작을 수행하기 때문에 낮은 계산을 요구할 뿐만 아니라 서로 다른 네트워크에서 USB 장치의 불리적인 접근을 예방하고 사용자의 불필요한 서비스 액세스를 허용하지 않기 때문에 통신 오버헤드 및 서비스 지연이 향상되었다. 실험에서 제안 프로토콜은 패킷 인증 지연시간과 USB 수에 따른 인증서버의 처리량을 단순파일 저장매체(USB driver)와 자체 연산 가능한 매체(USB Token) 등과 비교 평가하였으며, 실험 결과 인증 지연시간에서 평균 12.5% 향상되었고 USB수에 따른 인증서버의 처리량에서는 평균 10.8% 향상된 결과를 얻을 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.878-881
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• 2003

To acquire an appointed speaker's clear voice signal from inspect-camera, picture-conference or hands free microphone eliminating interference noises needs to be preceded speaker's position automatically. Presumption of sound source position's basic algorithm is about measuring TDOA(Time Difference Of Arrival) from reaching same signals between two microphones. This main project uses ADF(Adaptive Delay Filter) [4] and CPS(Cross Power Spectrum) [5] which are one of the most important analysis of TDOA. From these analysis this project proposes presumption of real time sound source position and improved model NI-ADF which makes possible to presume both directions of sound source position. NI-ADF noticed that if auditory sense of humankind reaches above to some specified level in specified frequency, it will accept sound through activated nerve. NI-ADF also proposes practicable algorithm, the presumption of real time sound source position including both directions, that when microphone loads to some specified system, it will use sounds level difference from external system related to sounds of diffraction phenomenon. In accordance with the project, when existing both direction adaptation filter's algorithm measures sound source, it increases more than twice number by measuring one way. Preserving this weak point, this project proposes improved algorithm to presume real time in both directions.

• 드라이브 ㆍ 컨트롤
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• 제17권4호
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• pp.46-53
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• 2020

In this paper, the development of a manually and continuously variable impact force control mechanism for hydraulic breakers was studied. Generally, a hydraulic breaker has one or two piston strokes. Hydraulic breakers, which have two strokes, have two valve-switching ports and make short and long piston strokes. The piston stroke valve controls the piston stroke by opening and closing a short stroke-switching port. The short piston stroke mode is used to break soft rock, concrete, or asphalt. This stroke control valve system is not popular for small hydraulic breakers mounted on 1 to 14-ton excavators. To preserve the carrier-like excavator, proper breaking force is needed, and it can be easily controlled by multiple piston stroke control valves. The easiest way to control these breakers is to use several switching ports and valves but they are not easy to install in small hydraulic breakers and are expensive. To use only one switching port and valve, a method can be used to change the open area of the switching port to delay valve switching. This method provides multiple piston strokes.

• 한국정보과학회논문지:시스템및이론
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• 제37권5호
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• pp.292-303
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• 2010

온칩(on-chip) 캐쉬는 외부 메모리로의 접근을 감소시키며 빈번하게 접근되기 때문에 내장형 시스템의 성능과 에너지 소비 측면에서 중요한 역할을 한다. 본 논문에서는 내장형 시스템에 맞추어 설계된 2-레벨 데이터 캐쉬 메모리 구조를 제안하고자 한다. 레벨1(L1) 캐쉬의 구성으로 작은 크기, 직접시장(direct-mapped) 그리고 바로쓰기(write-through)를 채용한다. 대조적으로 레벨2(L2) 캐쉬는 보통의 캐쉬 크기와 집합연관(set-associativity) 그리고 나중쓰기(write-back) 정책을 채용한다. 결과적으로 L1 캐쉬는 빠른 접근 시간을 가지며 (한 사이클 이내) L2 캐쉬는 전체 캐쉬의 미스율(global miss rate)을 낮추는데 효과적이다. 작은 크기의 L1 데이터 캐쉬로 인한 증가된 캐쉬 미스율(miss rate)을 줄이기 위해 ECP(Early Cache hit Predictor)기법을 제안하였다. 제안된 ECP기법은 L1 캐쉬 히트 예측을 통해서 요청된 데이터가 L1 캐쉬에 있는지 예측할 수 있으며 추가적으로, ALU를 필요로 하지 않고 빠르게 유효주소(effective address)계산을 할 수 있다. 또한, 두 캐쉬 계층간 바로쓰기(write-through) 정책에서 오는 빈번한 L2 캐쉬 접근으로 인한 에너지 소비를 줄이기 위해 지정웨이 쓰기(one-way write) 기법을 제안하였다. 제안된 지정웨이 쓰기 기법을 이용하면 바로쓰기 정책으로 인한 L1 캐쉬에서 L2 캐쉬로의 쓰기 접근시 태그(tag) 비교 과정을 거치지 않고 하나의 지정된 웨이를 바로 접근할 수 있다. 사이클 단위 정확도의 시뮬레이터와 내장형 벤치마크를 이용한 실험 결과 본 논문에서 제안한 2-레벨 데이터 캐쉬 메모리 구조는 평균적으로 3.6%의 성능향상과 50%의 데이터 캐쉬 에너지 소비를 감소 시켰다.