• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.316-328
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• 2003

In this paper, we propose and analyze two adaptive channel allocation schemes for supporting multimedia traffics in hierarchical cellular systems. It is guaranteed to satisfy the required quality of service of multimedia traffics according to their characteristics such as a mobile velocity for voice calls and a delay tolerance for multimedia calls. In the scheme 1, only slow-speed voice calls are allowed to overflow from macrocell to microcell and only adaptive multimedia calls can overflow from microcell to macrocell after reducing its bandwidth to the minimum channel bandwidth. In the scheme II, in addition to the first scheme, non-adaptive multimedia calls can occupy the required channel bandwidth through reducing the channel bandwidth of adaptive multimedia calls. The proposed scheme I is analyzed using 2-dimensional Markov model. Through computer simulations, the analysis model and the proposed schemes are compared with the fixed system and two previous studies. In the simulation result, it is shown that the proposed schemes yield a significant improvement in terms of the forced termination probability of handoff calls and the efficiency of channel usage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.774-782
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• 2003

Generally, in the Mobile IP technologies, the use of RSVP(Resource ReSerVation Protocol) is recommended in order to provide a mobile node real-time service. However, the handoff of a mobile node increases the registration delay, RSVP reservation delay and signalling overhead in the Mobile IP and RSVP interworking. Specially, the resource reservation on the path between a mobile node and a correspondent node is the duplicated reservation and then causes unnecessary creation of the signalling overhead and waste of the resource, since the majority of the path before handoff and after handoff is same. If the radius of a cell providing a wireless interface to a mobile node is small, the number of handoff will increase and also signalling overhead and duplicated resource reservation will increase. In this paper, we proposed the integration model of Cellular IP and RSVP with RSVP proxy scheme. Here, Cellular IP protocol minimizes registration delay, transfer delay, and loss by handoff in micro cell network, the RS VP proxy that minimizes the duplication of resource reservation prevents the path for RSVP session from change using the address for reservation of a mobile node. Proposed scheme was evaluated in comparison with the existing Mobile IP and RSVP interworking scheme using the probability of resource reservation fail to the radius of a cell and the handoff rate.

• Journal of KIISE:Information Networking
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• v.27 no.4
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• pp.453-464
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• 2000

본 논문에서는 계층셀 시스템에서 이동단말의 속도에 따른 채널 할당 기법이 갖는 QoS 차이를 극복하기 위하여 두가지 핸드오프 우선 순위 기법을 제안한다. 첫 번째 기법은 매크로셀에 고속 핸드오프 호를 위한 전용채널을 할당하여 고속 단말의 핸드오프 강제 종료율을 낮추어 줌으로써 서로 다른 속도 그룹에 속한 단말들에게 동일한 서비스 품질을 유지할 수 있도록 한다. 두 번째 제안하는 기법에서는 시스템 내 트래픽 양의 증가시에 발생하는 핸드오프 호의 성능 저하를 방지하기 위하여 마이크로셀 경계에 핸드오프 호를 위한 큐를 도입한다. 시뮬레이션 결과 핸드오프 호 강제 종료율에 있어서 높은 성능 개선을 보이며 특히 저속 단말에 준하는 수준으로 고속 단말의 QoS를 보장하였다. 또한 오버플로우 대 테이크백 비율(the ratio of take-back to overflow)을 고려할 때 기존 방식에 비하여 제안하는 방식에서 보다 많은 호가 올바른 셀 계층에서 진행하게 되어 전체 시스템의 효율을 높이는 것을 확인하였다.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.49-56
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• 2017

Curling sweeping is one of important motion to control the position of the curling stone, and sweeping speed and applied force to the broom pad are major research subjects. In this study, a device was developed to measure the force applied to the curling broom pad in curling sweeping motion, and two load cells were mounted between the broom pad and pad holder. Analog signals generated from the load cells were sampled about 300 times per second using a micro controller, and then converted to 10-bit digital signals. Calibration of the load cell and set up of regression equations to convert the measured electrical signals into mass (force) was done by three M1 class weights, and the developed system was designed as wearable device to minimize increasing of total weight of the broom. Same force was applied to the developed system and a force plate that was using as a reference force measurement system in field of sports, and the difference between the measured values were showed about $0.909{\pm}1.375N$(mean and standard deviation). The developed system could be applied other kinds of study which required force measurement function similar to sweeping motion.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.183-190
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• 2013

In this paper, we propose an improved anisotropic diffusion model for micro-crack detection in heterogeneously textured surface of polycrystalline solar wafers. Due to the nature of the image sensor, the gray-level of the diagonal micro-crack is non-uniform. Thus, the conventional algorithms can't fully detect diagonal micro-cracks when the number of iteration is not enough. However, the increasing of the iteration number leads to increase computation time and detects micro-crack thicker than the original micro-crack. In order to overcome this drawback, we use the gradient of north, south, east, and west directions as well as extended directions. To calculate the diffusion coefficients, we compare the gradients of conventional directions and extended directions and apply the larger gradient values to the coefficient function. This is because the proposed method reflects the information of diagonal micro-crack. Comparing to Tsai et al.'s and Ko and Rheem's, the proposed algorithm shows superior efficiency in detecting the diagonal micro-cracks with less iterations in the images of polycrystalline solar wafers. In addition, it also shows that the thickness of segmented micro-crack is similar to the orignal micro-crack.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.5
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• pp.21-29
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• 1999

이동횟수 기반 위치갱신 기법에서 고정망과의 접속은 단말 내부의 계수기가 이동횟수 임계치에 이르러 위치갱신이 수행되거나 신규호가 발생할 경우에 행해진다. 그러나 단말의 계수기가 임계치에 이르는 동시에 단말이 이전 위치갱신이 수행된 셀(중앙셀)로 재진입이 발생할 경우 불필요한 위치갱신이 수행된다. [2]에서는 중앙셀로 재진입이 발생하는 경우의 불필요한 위치갱신 수행을 제거하기 위해 중앙셀로 재진입이 발생할 경우 계수기를 영으로 초기화한다. 본 논문에서는 [2]의 기법을 일반화하여 위치갱신 비용을 절약할 수 있는 개선된 기법을 제안한다. 본 기법은 단말이 셀 사이를 이동하는 동안 단말은 자신이 방문한 셀과 이동횟수에 관한 정보를 저장한다. 단말이 이미 방문한 셀로 재진입이 발생할 겨우 이동횟수 계수기를 증가시키는 것이 아니라 이전 방문시 저장하였던 이동횟수로 재조정한다. 이러한 이동회수 계수기의 재조정 방법을 통하여 불필요한 위치갱신과 신호절차를 효과적으로 줄일 수 있다. [2]의 기법은 본 논문에서 제안하는 기법 중에서 중앙셀로 재진입할 때만 계수기를 영으로 재조정하는 특수한 경우에 해당된다. 본 기법이 전체 위치관리 비용을 크게 절약할 수 있음을 증명하기 위해 다양한 환경에서의 성능분석 및 수치적 결과를 통해 알아 본 결과 호 도착 비율당 전체 위치관리 비용이 평균 17-26% 절약됨을 관찰할 수 있었다.

• Journal of IKEEE
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• v.16 no.1
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• pp.34-44
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• 2012

This paper proposes a practical compensation method by using digital signal processing over the creep error which is representative in strain gauge loadcell. The signal compensation method carry out the simulation by deciding compensation constant (time constant) and coefficient measuring the loadcell output response. Then, compensation constant and coefficient are stored on the microprocessor. By using calculated on microprocessor creep error compensation values, weighting value is showed as a digital signal by reducing error values measured through output signals of loadcell. In addition, we apply error compensation method in order to have a dedicated software for loadcell electronic scale. This technique is useful because it has great influence on error rate reduction that has been produced by conventional electronic scales (0.03%). As a result our technique gives better accuracy (0.01%~0.003%) as what is given by digital electronic scale, while it has less complex operation processing.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1804-1820
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• 1997

In this paper, an efficient call control procedure is presented for next generation wireless ATM networks and its performance is mathematically analyzed using the open queueing network. This procedure is based on a new scheme called as the cell clustering. When we use the cell clustering scheme, at the time that a mobile connection is admitted to the network, a virtual cell is constructed by choosing a group of neighboring base stations to which the call may probabilistically hand over and by assigning to the call a collection of virtual paths between the base stations. Within a microcell/picocell environment, it is seen that the cell clustering can support effectively a very high rate of handovers, provides very high system capacity, and guarantees a high degree of frequency reuse over the same geographical region without requiring the intervention of the network call control processor each time a handover occurs. But since mobiles, once admitted, are free to roam within the virtual cell, overload condition occurs in which the number of calls to be handled by one base station to exceed that cell site's capacity of radio channel. When an overload condition happens, the quality of service is abruptly degraded. We refer to this as the overload state and in order to quantify the degree of degradation we define two metrics, the probability of overload and the normalized average time spent in the overload state. By using the open network queueing model, we derive closed form expressions for the maximum number of calls that can be admitted into the virtual cell such that the two defined metrics are used as the acceptance criteria for call admission control.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.10b
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• pp.1557-1560
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• 2000

이동 통신 분야에서 통신 기술의 발달에 의한 정보화 사회의 진전에 따라 비약적인 발전을 거듭하고 있다. 특히 이동 전화와 노트북과 같은 이동 단말기가 보편화됨으로써 셀룰러망이 빠르게 성장할 수 있었고, 제한된 라디오 스펙트럼에서 이동 단말기의 증가하는 수를 조정하기 위해 마이크로/피코셀룰러 구조와 같이 디자인되었다. 이와 같이 다수의 사용자를 수용하기 위해 셀 크기를 축소하게 되면 핸드오프 이벤트가 증가하게 되고 안정적인 서비스를 제공하기 위해 효과적으로 처리해 줄 수 있는 핸드오프 기술은 필수적이라 할 수 있다. 이 논문에서는 이웃에 있는 셀에 셀룰러 트래픽의 양에 따라 핸드오프 호에 예약한 셀 안에 대역폭의 양을 동적으로 조정하는 Population-Based Reservation구조에서의 Fractional Parameter에 대한 성능을 분석하였다. 이 파라미터의 값은 QoS 요구를 기본으로 결정되어져야 하고 요구사항을 충족시키기 위해 변화하는 트래픽 상태들에 따라 동적으로 조절되어질 수가 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.501-502
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• 2006

In-plane type micro piezoelectric micro grippers with pneumatic lines for manipulation biological cells and micro parts were designed, fabricated, and characterized. Micro grippers were fabricated through the final micro-sanding process after wafer level bonding between the etched 4' Si wafer with pneumatic channels and 4' glass wafer. Displacements between two jaws of fabricated micro grippers were linearly increased with applying voltages to piezoelectric actuator. In the case of applying 80 V, the displacement between two jaws was $160{\mu}m$. Using fabricated micro grippers, manipulation tests for biological cell and micro parts with the sizes less than $100{\mu}m$ are in process.