• 한국통신학회논문지
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• 제29권12C호
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• pp.1722-1728
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• 2004

다수의 인증 경로가 존재하는 PKI 구조에서 인증 경로를 설정하는 것은 중요한 문제이다. 경로 설정은 다양한 검증을 통해 이루어지고 검증이 많을수록 경로의 유효성은 높아진다. 유효성 높은 경로의 선택은 경로 설정 및 검증 작업의 반복 횟수를 감소시킴으로서 고속의 인증서 검증이 가능하도록 하는 반면에 하나의 경로를 설정하는데 소요되는 시간 및 부담을 증가시킨다는 문제점을 가진다. 본 논문에서는 보다 적은 부합으로 경로의 유효성을 높일 수 있는 효율적인 인증 경로 설정 알고리즘을 제안한다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.215-218
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• 2003

In order to study the frost heaving characteristics of soil stabilitized with a quick lime, a cement and a briquette ash, frost heaving tests were performed with 2 kinds of soil sampled at Chonbuk-Do area. Frost heaving of no-stabilizing soil compacted with water content greater than optimum water content was increased as the frost period was increased but in case of samples with water content smaller than optimum water content, the frost period gave no affect about increase and decrease of the frost heaving. Both frost heaving of stabilizing and no-stabilizing soil with water content greater than optimum water content was decreased with the increase of the repetition number of freezing and thawing. There was no increase or decrease of frost heaving in the frost heaving test after 5 times of freezing and thawing.

• 한국세라믹학회지
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• 제30권9호
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• pp.761-767
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• 1993

Electrical and mechanical properties of Pb(Mg, Te, Mn, Nb)O3-PZT ceramics are investigated as a function of CeO2 addition (0 to 0.3wt%), and the output characteristics of piezoelectric transformer are also presented. The grain size decreased and the shapes of particles were more uniform with the addition of CeO2. The coercive electric field(9500V/cm), mechanical quality factor (2500) and bend strength (1065kg/$\textrm{cm}^2$) were improved by addition of CeO2 0.2wt%. After repetition of a number of stress cycles, the degradation of k33 was not found in this sample. The voltage step-up ratio (Vdc/Vrms) of piezoelectric ceramic transformer (half wavevoltage doubler, load resistor 100M.ohm) was about 950 in a linear region, its value was relatively higher than other materials.

• International Journal of Reliability and Applications
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• 제5권1호
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• pp.15-24
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• 2004

Folder type electronic devices have hinge to support the rotational motion of folder. This hinge is stressed by the rotational inertia moment of folder at the maximum open limit position of folder. This stress is repeated whenever the folder is open, and it is a cause of hinge fracture. In this paper, the reliability evaluation for the hinge fracture in the folder type cellular phone is discussed. For this, the durability testing machine using crank-rocker mechanism is developed to evaluate the life cycle of the hinge, and the degradation after repetitions of opening and shutting is evaluated from the deformation around the hinge, where the deformation is measured by ESPI (electronic speckle pattern interferometer). Experimental results showed that ESPI was able to measure the deformation of hinge precisely, so we could monitor the change of deformation around the hinge as the repetition number of folder open is increased.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2005년도 추계학술대회 논문집
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• pp.36-39
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• 2005

Information on temporal evolution of whole velocity fields is essential for physical understanding of a complicated turbulent flow and was obtainable using dynamic PIV because of advances of high-speed imaging technique, laser and electronics. A dynamic PIV systme consists of a high-speed CMOS camera having $1K\times1K$ pixels resolution at 1 KHz and a high-repetition Nd:Yag pulse laser. In order to validate its performance, the dynamic PIV system was applied to a turbulent jet whose Reynolds number is about 3000. The particle images of $1024\times512$ pixels were captured at a sampling rate of 4 KHz. The dynamic PIV system measured successfully the temporal evolution of instantaneous velocity fields of the turbulent jet, from which spectral analysis of turbulent structure was also feasible.

• Animal cells and systems
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• 제5권4호
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• pp.313-317
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• 2001

The sequential assessment model describes a fight between two conspecific as an ongoing statistical sampling process, which makes it possible to predict fight length or repetition number of a behavioral element depending on relative RHP (resource holding potential: e.g. weight or fighting ability). We staged contests between males of common freshwater gobies to test some predictions of this model. Fights proceeded in a consistent sequence of phases. Most contests began with two contestants adopting lateral display, and then escalated to intense physical contacts. The length of contests was negatively correlated with weight difference between the contestants. The duration of complete phases was, however, independent of weight, and the prior information gained during complete phases did not appear to affect subsequent phases of the fight. Our results show that the contests of common freshwater gobies are well predicted by the sequential assessment model.

• 음성과학
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• 제10권2호
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• pp.159-168
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• 2003

The purpose of this study was to assess the speech rate, fluency and the type of dysfluencies of normal adults in order to provide a basic data of normal speaking. The number of subjects of this study were 30(14 females and 16 males), and their ages ranged 17 to 36. The rate was measured as syllables per minute (SPM). The speech rates in reading ranged 273-426 with a mean of 348 SPM and in speaking ranges 118-409 (mean=265). The average of their fluencies was 99.1% in reading and 96.9% in speaking. The rater reliability of speech rate in the data assessed by video was very high (r=0.98) and the rater reliability of speech fluency was moderately high (r=0.67). The disfluency types were also analysed from 150 disfluency episodes. Syllable repetition and word interjection were the most common disfluent types.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권12호
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• pp.601-607
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• 2002

IPMC(Ionic Polymer Metal Composite)actuators were optimized for producing improved forces by changing multiple parameters including repetition of number of plating, surface electroding and additive(PVP)-treatment on reduction. The platinum electrode is deposited on the surface of the material where platinum particle stay in a dense form that appears to introduce a significant level of surface electrode resistance. Actuation tests were performed for such IPMC actuators under a low voltage. The test results show that the lower surface-electrode resistance generates higher actuation capability in the IPMC actuators. In order to investigate relaxation behavior of bending and repeatability in dry condition, the IPMC was coated by$rubber(KRATON^{TM})$to minimize the effect of water evaporation from IPMC. This actuator can be used in air with surface coating to avoid membrane drying.

• 대한전기학회논문지
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• 제36권11호
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• pp.806-812
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• 1987

The ozone generation characteristics are reported for a sawtooth disk to cylinger geometry using positive and negative pulse corona. A series of parametric studies was carried out to obtain optimum values for the pulse repetition frequency as well as the shape and dimensions of the discharge disk and the discharge spacing. Two types of ozonizers were studied: the single disk and the multi-disk. The results of the single disk ozonizer showed that positive corona produced a singificantly higher ozone yield than negative(7ppm/peak watt or 3.5 times larger). However the negative corona produced a much more controllable output which enabled the ozone generation to be directly controlled by adjusting the value of the peak pulse voltage. This results showed that the single disk ozonizer is ideally suited for applications requiring very small controlled quantities of ozone whereas the multi-disk unit can be designed to provide varying outputs depending upon the number of disk electrodes used.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 봄 학술논문 발표대회
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• pp.170-171
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• 2022

In recent years, due to the occurrence of traffic accidents caused by black ice in winter, the number of personal injuries is increasing rapidly. Black ice is a phenomenon that occurs like a thin layer of ice on the road surface. Accordingly, many developments of heat-generating concrete are being developed to remove ice by increasing the temperature by supplying constant electricity to places where black ice is likely to occur. These heating elements are being developed by mixing a conductive material represented by carbon nanotubes with concrete. However, research up to now has been focused on efficient temperature rise and derivation of the optimum mixing ratio, and the evaluation of maintaining heat generation performance during continuous repetition is insufficient. Therefore, in this study, a heating test specimen was manufactured and 50V power was repeatedly supplied to evaluate the heating characteristics.