• Annals of Clinical Neurophysiology
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• 제19권1호
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• pp.34-39
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• 2017

Background: Automated nerve excitability testing is used to assess various peripheral neuropathies and motor neuron diseases. Comparing these excitability parameters with normal data provides information regarding the axonal excitability properties and ion biophysics in diseased axons. This study measured and compared normal values of axonal excitability parameters in both the distal motor and sensory axons of normal Koreans. Methods: The axonal excitability properties of 50 distal median motor axons and 30 distal median sensory axons were measured. An automated nerve excitability test was performed using the QTRACW threshold-tracking software (Institute of Neurology, University College London, London, UK) with the TRONDF multiple excitability recording protocol. Each parameter of stimulus-response curves, threshold electrotonus, current-voltage relationship, and recovery cycle was measured and calculated. Results: Our Korean normal data on axonal excitability showed ranges of values and characteristics similar to previous reports from other countries. We also reaffirmed that there exist characteristic differences in excitability properties between motor and sensory axons: compared to motor axons, sensory axons showed an increased strength-duration time constant, more prominent changes in threshold to hyperpolarizing threshold electrotonus (TE) and less prominent changes in threshold to depolarizing TE, and more prominent refractoriness and less prominent subexcitability and superexcitability. Conclusions: We report normal data on axonal excitability in Koreans. These data can be used to compare various pathological conditions in peripheral nerve axons such as peripheral neuropathies and motor neuron disease.

• 한국컴퓨터정보학회논문지
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• 제12권6호
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• pp.167-175
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• 2007

퍼지이론은 생명정보공학에서 지식을 표현하는데 활용되고 제어시스템 모델을 이해하는데 활용되어 왔다. 본 논문에서는 생명정보학의 응용 프로그램에서 중요한 데이터 분류에 초점을 맞추었다. 최적의 임계값 유도를 위한 GPCR 분류에서 기존의 순차기반 임계값 제어기법은 임계값 결정범위와 최적의 임계값 유도 시간의 문제점을 보였고, 이진기반 임계값 제어기법은 임계값 결정 초기에 시스템의 안정성에 대한 단점이 있었다. 이를 보완하기 위해 우리는 ART1 군집화를 위한 퍼지기반 임계값제어기법을 제안한다. 제안된 방법의 성능을 평가하기 위해 ART1 군집화를 위한 퍼지기반 임계값 제어기법을 구현하여 기존의 순차기반 임계값 제어기법과 이진기반 임계값 제어기법과의 인식률에 대한 구동시간의 변화, 임계값의 변화에 따른 시스템의 구동시간을 측정하였다. 퍼지기반 임계값제어 기법은 GPCR 데이터 분류에서 인식률과 구동시간에 대한 정보를 통해 분류 임계값을 조정하여 높은 인식률과 낮은 구동시간을 지속적으로 유도하여 안정적이고 효과적인 분류 시스템을 만들 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.527-532
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• 2010

In this study, vertical and horizontal accelerometers were installed at the both side of car body and tachometer was installed on the bogie, for the purpose of stability analysis of Korail Airport Express Train during driving. By applying the developed algorithm, the peak-to-peaks of horizontal and vertical acceleration which were matched with location by tachometer were found and compared with the threshold values. The threshold values per velocities which were presented in the "Metro Train Performance Criteria" were applied here. The validity of the developed algorithm was shown by comparing the site investigation and the measured values at frost heave locations.

• 한국컴퓨터정보학회논문지
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• 제10권6호
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• pp.65-74
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• 2005

본 논문에서는 비디오의 자동분류를 지원하기 위한 기반기술로서. 변형된 $x^{2}$-테스트와 자동 임계치 결정 알고리즘을 이용한 장면전환 검출 방법을 제안하였다. 변형된 $x^{2}$-테스트는 기존의 컬러 히스토그램과 각 채널 공간(RGB)에 NTSC표준에 따른 명암도 등급을 따로 계산하여 채널의 차이 값을 보다 세분화 할 수 있으며, 두 프레임사이의 상대적인 컬러 값 차이를 강조하는 기존의 $x^{2}$-테스트를 결합하여 보다 강건한 장면전환을 검출할 수 있다. 자동 임계치 결정 알고리즘은 연속된 프레임들로부터 변형된 $x^{2}$-테스트를 이용하여 추출된 차이 값을 이용한다. 먼저, 주어진 전체 차이 값들로부터 평균과 표준편차를 구하며, 이 평균값을 만족하는 차이 값들로부터 다시 평균과 표준편차를 계산하며, 이러한 연속적인 평균값 및 표준편차의 계산으로부터 표준편차가 가장 큰 시점에서의 평균값을 기준으로 임계치를 결정하는 방법이다. 제안된 방법은 다양한 비디오 데이터에서 실험되었으며, 실험결과 제안된 방법은 자동 임계치 결정에 효율적이며, 신뢰할만한 장면들을 검출하였다.

• 말소리와 음성과학
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• 제2권3호
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• pp.157-164
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• 2010

This study investigated the characteristics of two aerodynamic indices, PTP (Phonation threshold pressure) and PTF (Phonation threshold flow) in patients with ADSD (adductor spasmodic dysphonia) and to see if two new aerodynamic indices can differentiate between normal and ADSD group. Additionally, PTP and PTF values were compared in terms of overall severity of ADSD in the patient group. The severity of ADSD was rated on a 7-point rating scale by two experienced speech language pathologists. The Kay Elemetrics Phonatory Aerodynamic System (PAS) (Kay Elemetrics Corp., Lincoln Park, NJ) was used to collect PTP and PTF measurements from 16 female normal subjects, 31 female patients with ADSD. Significantly lower PTF values (P< 0.05) were observed in ADSD when compared to those of normal control. Also, significantly lower PTF values in severe ADSD patients (P<.001). However, PTP could not distinguish patients with ADSD from control groups (P=0.119) and among the ADSD groups according to the severity (P=0.177). Consequently, PTF was more sensitive than PTP which might differentiate between normal speakers and ADSD and among different levels of severity within ADSD, suggesting that PTF could be a useful diagnostic parameter to measure the aerodynamic function of ADSD and provide the neurolaryngeal dysfunction in patients with ADSD.

• 대한원격탐사학회지
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• 제33권4호
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• pp.359-375
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• 2017

We developed fog detection algorithm (KNU_FDA) based on the optical and textural properties of fog using satellite (COMS) and ground observation data. The optical properties are dual channel difference (DCD: BT3.7 - BT11) and albedo, and the textural properties are normalized local standard deviation of IR1 and visible channels. Temperature difference between air temperature and BT11 is applied to discriminate the fog from other clouds. Fog detection is performed according to the solar zenith angle of pixel because of the different availability of satellite data: day, night and dawn/dusk. Post-processing is also performed to increase the probability of detection (POD), in particular, at the edge of main fog area. The fog probability is calculated by the weighted sum of threshold tests. The initial threshold and weighting values are optimized using sensitivity tests for the varying threshold values using receiver operating characteristic analysis. The validation results with ground visibility data for the validation cases showed that the performance of KNU_FDA show relatively consistent detection skills but it clearly depends on the fog types and time of day. The average POD and FAR (False Alarm Ratio) for the training and validation cases are ranged from 0.76 to 0.90 and from 0.41 to 0.63, respectively. In general, the performance is relatively good for the fog without high cloud and strong fog but that is significantly decreased for the weak fog. In order to improve the detection skills and stability, optimization of threshold and weighting values are needed through the various training cases.

• Applied Microscopy
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• 제47권1호
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• pp.43-49
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• 2017

A new method was introduced to distinguish the ferrite, bainite and martensite in transformation induced plasticity (TRIP) steel by using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). EBSD is a very powerful microstructure analysis technique at the length scales ranging from tens of nanometers to millimeters. However, iron BCC phases such as ferrite, bainite and martensite cannot be easily distinguished by EBSD due to their similar surface morphology and crystallographic structure. Among the various EBSD-based methodology, image quality (IQ) values, which present the perfection of a crystal lattice, was used to distinguish the iron BCC phases. IQ values are very useful tools to discern the iron BCC phases because of their different density of crystal defect and lattice distortion. However, there are still remaining problems that make the separation of bainite and martensite difficult. For instance, these phases have very similar IQ values in many cases, especially in deformed region; therefore, even though the IQ value was used, it has been difficult to distinguish the bainite and martensite. For more precise separation of bainite and martensite, IQ threshold values were determined by a correlative TEM analysis. By determining the threshold values, iron BCC phases were successfully separated.

• 한국도로학회:학술대회논문집
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• 한국도로학회 2010년 추계학술대회 논문집
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• pp.127-132
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• 2010

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권11호
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• pp.2597-2615
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• 2013

This paper proposes a dynamic downlink load control scheme that jointly employs dynamic load threshold management and virtual coverage management schemes to reduce the degree of performance degradation due to traffic overload in two-tier femtocell networks. With the proposed scheme, the downlink load in a serving macrocell is controlled with a load threshold which is adjusted dynamically depending on the varying downlink load conditions of neighboring macrocells. In addition, traffic overloading is alleviated by virtually adjusting the coverage of the overloaded serving macrocell, based on the adjusted load threshold of the serving macrocell. Simulation results show that the proposed scheme improves the performance of two-tier femtocell networks in terms of the outage probability and sum throughput. This improvement is significantly increased with appropriate values of load thresholds and with an intermediate-level adjustment of the virtual coverage area (i.e., handover hysteresis margin: HOM). Furthermore, the proposed scheme outperforms both a previously proposed load control scheme with a static load threshold and the LTE system without a HOM adjustment.

• Structural Engineering and Mechanics
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• 제43권2호
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• pp.199-209
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• 2012

Two carbon fiber composite laminates, $[0/90]_{2S}$ and $[0/+45/90/-45]_S$, were considered in this work to find out the perforation threshold energy to complete the perforation process and the corresponding maximum contact force. Explicit finite element commercial software, LS-DYNA, was used to predict these values. According to the simulation results, these two types of composite laminates were tested by using a vertical drop-weight testing machine. After testing, the damage condition of these specimens were observed and compared with the results from finite element analysis. The testing results indicate that the perforation threshold energy is 6 Joules for $[0/90]_{2S}$ and 7 Joules for $[0/+45/90/-45]_S$, which is in good agreement with the simulation results. Also, the maximum contact force at the case of perforation threshold energy is the lowest as compared to the maximum contact forces occurring at the impact energy that is larger or less than the perforation threshold energy.