• Review of KIISC
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• v.27 no.1
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• pp.31-38
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• 2017

오랜 기간 널리 사용되어온 패스워드 인증 기법은 여전히 대표적인 사용자 인증 수단이지만 그 사용성과 안전성 측면에서 여러모로 부정적인 부분이 많다. 일반적으로 사용자는 기억하기 쉽도록 간단한 패스워드를 선택하는 반면 서버는 추측공격에 대해 비교적 안전하도록 복잡한 패스워드의 사용을 권장한다. 취약한 패스워드의 사용은 전체 시스템의 안전에 큰 영향을 미치게 되므로 사용자가 패스워드를 선택하는 시점에 미리 패스워드의 강도 즉 안전성을 측정하여 피드백하기 워한 기법에 관한 연구가 다각적으로 이루어져 왔다. 또한 그 일부를 다양한 방법으로 시각화하여 이미 상용시스템에 적용하고 있다. 하지만 여전히 정확한 강도 측정과 안전한 패스워드의 사용성 제고를 위한 해결이 필요하며 따라서 이와 같은 패스워드 강도 측정 방법의 일반화를 위한 연구가 꾸준히 진행되고 있다. 본 논문에서는 텍스트 기반의 패스워드 강도 측정에 관한 연구동향을 살펴보고 분석한다.

• Proceedings of the Korea Multimedia Society Conference
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• 2002.11b
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• pp.287-290
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• 2002

본 논문에서는 디지털 컨텐츠 저작권 보호를 위해 강인성과 비가시성의 유지를 위한 보다 효과적인 방법으로 웨이브릿 변환에서 적응적 워터마크 삽입강도를 갖는 지각적 데이터 은닉 모델을 제안한다. 먼저 영상을 9/7 쌍직교 웨이브릿 필터를 사용해 4레벨로 다해상도 분해한다. 다음으로 연속부대역 양자화(successive subband quantization)를 통한 시각적 중요계수(perceptually significant coefficient: PSC)들을 선정하여 선택된 계수들에 대해서만 워터마크 정보를 삽입한다. 지각 모델은 정상상태의 일반화 가우시안 모델(generalized gaussian model)로 추정된 NVF(noise visibility function)로 에지와 텍스쳐영역 그리고 평탄영역에 따라 각각 적응적으로 삽입되게 한다. 이는 각 서브밴드 내의 분산과 형상계수(shape parameter)에 의해 결정된다. 적응적 워터마크의 삽입강도를 갖기 위해 에지와 텍스쳐영역의 삽입강도는 각 서브밴드의 주파수 감도(frequency sensitivity)로 결정되고, 평탄영역의 삽입강도는 영상의 국부적 특성에 근거한 통계적 가중치를 사용한다. 삽입되는 워터마크는 랜덤시퀀스로 N(0,1)이다. 여러 가지 공격에 대한 실험으로 제안한 방법의 비가시성과 강인성을 확인한다.

• Journal of Internet Computing and Services
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• v.23 no.2
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• pp.53-59
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• 2022

After the 3rd level autonomous driving vehicle, the 4th and 5th level of autonomous driving technology is trying to maintain the optimal condition of the passengers as well as the perfect driving of the vehicle. However current autonomous driving technology is too dependent on visual information such as LiDAR and front camera, so it is difficult to fully autonomously drive on roads other than designated roads. Therefore this paper proposes a Braking Strength Calculation System (BSCS), in which a vehicle classifies road conditions using data other than visual information and calculates optimal braking strength according to road conditions and driving conditions. The BSCS consists of RCDM (Road Condition Definition Module), which classifies road conditions based on KNN algorithm, and BSCM (Braking Strength Calculation Module), which calculates optimal braking strength while driving based on current driving conditions and road conditions. As a result of the experiment in this paper, it was possible to find the most suitable number of Ks for the KNN algorithm, and it was proved that the RCDM proposed in this paper is more accurate than the unsupervised K-means algorithm. By using not only visual information but also vibration data applied to the suspension, the BSCS of the paper can make the braking of autonomous vehicles smoother in various environments where visual information is limited.

• The Korean Journal of Applied Statistics
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• v.12 no.2
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• pp.563-572
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• 1999

수리가능한 시스템에 대한 고장시간이 여러 가지 모형에 대한 연구가 최근들어 신뢰성분야의 학자들에 의해 활발히 이루어지고 있다. 본 논문에서는 수리 가능한 시스템의 고장이 와이블과정을 따라 일어날 경우, 고장 시각 $t_n$에서의 강도함수 $\lambda$($t_n$)의 최우추정량의 분사이 형상모수인 $\beta$의 값에 따라 충분히 큰 n에 대하여 수렴 여부를 밝혔다.

• Journal of Oral Medicine and Pain
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• v.32 no.4
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• pp.383-396
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• 2007

The aim of this study was to measure the suprathreshold taste intensity for NaCl, sucrose, citric acid, and quinine HCl in elderly Korean women using a whole-mouth, sip-and-spit procedure, employing the method of magnitude matching. The results were analysed in terms of aging, menopause, and salivary flow rate. 31 elderly women (mean age; $50.8{\pm}5.1$ years) and 30 young women (mean age; $25.1{\pm}1.71$ years) were included for the study. Subjects were instructed to give nonmodulus magnitude estimates to the intensities of five concentrations each of sucrose, NaCl, citric acid, and quinine HCl; distilled water; 6 loudness level of a 1,000-Hz tone, using the same 9-point intensity scale. Each of the 21 taste stimuli and 6 auditory stimuli are presented in random order twice. The auditory function is used to assess the absolute intensity function of the subject's taste system. The results were as follows; 1. Comparing to young women, elderly women showed decreased taste intensities for lower concentration solutions of NaCl and sucrose. However, other solutions didn't show any difference in taste intensities between young and elderly women. 2. There were not significant difference in perceived taste intensities for NaCl, sucrose, citric acid, and quinine HCl between menopause and pre-menopause women in elderly women group. 3. There were not significant difference in perceived taste intensities for NaCl, sucrose, and quinine HCl between low salivation women and high salivation women in elderly women group. 4. The low salivation women in elderly group showed higher taste intensity for low concentration citric acid than high salivation women.

• Journal of Korean Society of Transportation
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• v.23 no.3 s.81
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• pp.85-94
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• 2005

The scale and operating conditions of logistical systems very sensitively varies according to the variation of traffic intensity that is affected by the arrival characteristics of trucks and the attributes of loading/unloading services in logistics facilities. More exactly, logistics costs are incurred according to variations of traffic intensity. which are intimately linked with in a given time period. Also. although traffic intensity changes minutely, the range of cost variation is wide. Nevertheless, with regard to operating logistics systems, the existing studies make no attempt to analyze these factors. Therefore, it was the purpose of this study to determine the optimal traffic intensity to minimize excessive logistics costs resulting from the generation of unnecessary costs such as waiting costs and overcosts in operating a facility. For the purposes of this analysis. a determination model of optimal traffic intensity was constructed according to queuing theory. The inflow/outflow conditions of trucks and the terminal operational conditions were collected from an off-dock container terminal in Busan. On the basis of this data. the optimal traffic intensity that could off-set excessive waiting and operating costs was determined quantitatively. Also. using the optimal traffic intensity to be determined. we consider the improvements of operating system in the logistics facilities.

• Annual Conference on Human and Language Technology
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• 1994.11a
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• pp.235-250
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• 1994

한글의 신속하고 정확한 정보전달 기능을 유지 발전 시킴과 동시에, 정보 전달의 목적 및 효율성을 높이기 위하여, 인간심리에 직접 영향 미치는 시각적 이미지를 지니는 조형적 문자의 서체 및 기능 개발에 필요한 현행 한글서체들의 시각적 이미지에 대한 분석적 연구를 시도하였다. "한글의 시각적 이미지 다양화에 관한 연구" 에서의 네모틀 고수형의 한글 이미지 연구에 이어 금번에는 컴퓨터에서 지원 사용되는 탈네모꼴의 한글 12종을 제목용과 본문용으로 나누고 각각 그 굵기에 따른 이미지를 표본조사 및 수치분류적 기법에 의한 이미지 특성을 분석하였다. 연구결과, 한글 탈내모꼴 서체는 크게 3개의 그룹으로 구분되며, 전반적으로 그 이미지의 강도에 있어 약한것으로 나타났으며, 각 서체의 제목용및 본문용의 각각의 굵기에 해당하는 이미지가 동일한 것으로 나타나 안정된 이미지를 보유하는 서체로는 스케치체와로 나타났다. 이 같은 한글서체의 이미지 분류 연구는, 한글서체 개발이 수치적 분석에 의하여 방향정립 및 높은 예측성을 지닐 수 있으며, 목적지향적인 폰트개발 및 균형있는 서체운용 체계의 운용에 의하여 극대화될 수 있다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.157-168
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• 2014

We propose an novel artificial visual attention model that is capable of automatic detection and segmentation of saliency region on natural images in this paper. The proposed model is based on human visual perceptions in biological vision and contains there are main contributions. Firstly, we propose a novel framework of artificial visual attention model based on the opponent process theory using intensity and color features, and an entropy filter is designed to perceive salient regions considering the amount of information from intensity and color feature channels. The entropy filter is able to detect and segment salient regions in high segmentation accuracy and precision. Lastly, we also propose an adaptive combination method to generate a final saliency map. This method estimates scores about intensity and color conspicuous maps from each perception model and combines the conspicuous maps with weight derived from scores. In evaluation of saliency map by ROC analysis, the AUC of proposed model as 0.9256 approximately improved 15% whereas the AUC of previous state-of-the-art models as 0.7824. And in evaluation of salient region segmentation, the F-beta of proposed model as 0.7325 approximately improved 22% whereas the F-beta of previous state-of-the-art models.

• Journal of Korea Water Resources Association
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• v.31 no.1
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• pp.3-12
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• 1998

Rainfall intensity under storms affects peak discharge or its time of occurrence in watershed runoff. Thus, it is reasonable to reflect the effect on the parameters of rainfall-runoff models or the governing equations of the models. This paper relates the change of the runoff coefficient of the first tank in tank model to rainfall intensity under storms. The standard four tanks have made the basic structure of the flood event model. and its modifications are as follows: it has two equal runoff coefficients in the first tank: the runoffs from first and second tanks produce delayed response through a simple delaying parameter. Applying the event simulation model to flood data from Naerinchon. runoff coefficients were estimated and their relation to rainfall intensity was analyzed. The results showed the Weak relation of the two factors. The trend of the two was fitted with the equation a1=kI$. where a1is the runoff coefficient of the first tank: I is rainfall intensity; k and m are fitting coefficients. In the verification. the model used moving averages for the calculation of I(t). If the value I(t) gave more greater value of a1(t) than that of previous time(t-1). the flood simulation was performed again from the beginning with the updated greater value of a1. The reflection of rainfall intensity on the runoff coefficient showed far better results than that of a fixed parameter.

• Journal of Sensor Science and Technology
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• v.12 no.2
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• pp.57-65
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• 2003

When a vision chip for edge detection using CMOS process is designed, there is a necessity to implement local light adaptive-function for detecting distinctive features of an image at a wide range of light intensities. Local light adaptation is to achive the almost same output level by changing the size of receptive-fields of the local horizontal cell layers according to input light intensities, based on the lateral inhibitive-function of the horizontal cell. Thus, the almost same output level can be obtained whether input light intensities are much or less larger than background. In this paper, the horizontal cells using a resistive network which consists of p-MOSFETs were modeled and analyzed, and the local light adaptive-mechanism of the designed vision chip using the resistive network was verified.