• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.198-199
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• 2023

본 연구에서는 조선왕조실록을 중심으로 조선시대의 호우 및 홍수기록의 기술방법에 대해 텍스트마이닝 분석을 실시하였다. 조선왕조실록은 조선시대의 큰 호우사상은 모두 포함하고 있기 때문에 이를 일정한 등급으로 나누어 분류한다면 극치 호우 사상의 발생특성을 이해하는데 도움이 될 수 있다. 전체적으로 '큰비'에서와 같이 강우에 대한 언급만이 있는 경우가 '큰물', '홍수', '폭우'와 같이 홍수유출 및 이에 따른 피해가 설명되어 있는 경우보다 강우의 재현기간이 작게 나타나는 것을 파악할 수 있었다. 또 하나 주목할만한 점은 기록된 호우사상이 강우의 총량보다는 강우의 지속기간에 보다 민감하다는 점이다. 즉, 일시에 많은 비가 온 경우보다는 장기간에 걸쳐 내린 호우사상에 보다 초점이 맞추어져 있다는 점이다. 즉, 홍수유출의 크기 및 이에 따른 피해의 정도가 실제 이들 호우사상이 기록으로 남게 되는 원인으로 파악된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.954-957
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• 2008

EPON(Ethernet Passive Optical Network)은 저비용의 Ethernet 장치와 광섬유 인프라를 융합한 네트워크로서 차세대 광대역 액세스 네트워크에서 'last mile'의 병목현상을 해결하기 위해 개발된 기술이다. EPON에서는 업스트림 방향으로 하나의 파장을 이용해 전송해야 하므로 TDMA(Time-Division Multiple Access) 방식을 이용하는데, 한정된 대역폭을 효율적으로 할당하기 위해서 주로 할당하는 윈도우의 크기에 비중을 두었으나, 본지에서는 할당하는 순서에 연구의 초점을 두었다. 제안 방식은 ONU(Optical Network Unit)들을 여러개의 그룹으로 나누고 요구량에 따라 최대 최소를 찾아 최대는 가장 먼저 최소는 가장 늦게 폴링하게 한다. 제안하는 방식은 기존 DBA(Dynamic Bandwidth Allocation) 알고리즘과의 성능평가 결과를 놓고 볼 때, 지연시간과 처리율면에서 높은 향상을 보인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.579-582
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• 2007

최근 들어 더욱 UCC(User Created Contents)등과 같은 대용량 멀티미디어(multimedia) 서비스에 대한 요구가 나날이 증가되면서 부하분산에 중점을 둔 웹 클러스터링 시스템(Web Clustering System) 에서 기존의 작은 크기의 스트림 데이터(Stream Data)나 조금 더 다양한 데이터를 위한 읽기 성능을 대용량 데이터에 초점을 맞춘 방안으로 최적화 시키는 것이 중요시되고 있다. 본 논문에서는 대용량 멀티미디어를 중심으로 실제 서비스시 간과 되어질 수 있는 운영체제(Operating System, O/S)에서의 I/O 인식, 디스크 제어 프로그램에서의 I/O, 웹 클러스터의 부하분산정책의 파라미터(Parameter)를 개선함으로써 읽기성능 향상 방안을 제시한다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.75-87
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• 2009

We propose in this paper a novel approach to image fusion in which the fusion rule is guided by optimizing an image clarity function. A Genetic Algorithm is used to stochastically select, comparative to the clarity function, the optimum block from among the source images. A novel nested Genetic Algorithm with gifted individuals found through bombardment of genes by the mutation operator is designed and implemented. Convergence of the algorithm is analytically and empirically examined and statistically compared (MANOVA) with the canonical GA using 3 test functions commonly used in the GA literature. The resulting GA is invariant to parameters and population size, and a minimal size of 20 individuals is found to be sufficient in the tests. In the fusion application, each individual in the population is a finite sequence of discrete values that represent input blocks. Performance of the proposed technique applied to image fusion experiments, is characterized in terms of Mutual Information (MI) as the output quality measure. The method is tested with C=2 input images. The results of the proposed scheme indicate a practical and attractive alternative to current multi-focus image fusion techniques.

• Korean Journal of Social Welfare
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• v.65 no.4
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• pp.341-365
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• 2013

This study attempts to examine the moderating effect of religiosity in the relationship between religion and secular giving behavior (absolute amount and philanthropic effort). For the analysis, this study utilizes 'Giving Korea 2012' by the Beautiful Foundation and employs Tobit regression model. Focusing on giving amount, major findings are that (1) Protestants and Catholics give greater amounts for secular cause than those with no religious affiliation; and (2) interaction between Protestants and religiosity and interaction between Catholics and religiosity have significant relationships with citizens' secular giving amount in a positive direction. Focusing on philanthropic effort (giving amount divided by family income), major findings are that (1) there is no significant relationship between religion types and citizens' philanthropic effort and (2) interaction between Protestants and religiosity and interaction between Catholics and religiosity have significant relationships with citizens'philanthropic effort in a positive direction. This study provides new knowledge foundation on citizens' secular giving behavior and contributes to developing effective fundraising strategies of nonprofit organizations on religion-related donor markets.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.1
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• pp.13-18
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• 2000

In this paper, we use the C light which is a daylight and consider the incident beam having the Gaussian amplitude. We investigated the illuminance distributions and the variation in chromaticity of optical system having the truncated Gaussian amplitude on the focal plane and along the optical axis using the C light source. We also use the three sensitivity functions of human eye(CIE 1931) for wavelengths which are from 380nm to 780nm. When the truncation grade of incident beam having Gaussian amplitude decreases, the size of central spot on the focal plane and the depth of focus along the optical axis decrease, and the variation in chromaticity on the focal plane and along the axis increases rapidly. As the illuminance on the focal plane decreases the variation in chromaticity of optical system increases rapidly, and as the depth of focus increases the variation in chromaticity of optical system decreases.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.4
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• pp.75-88
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• 2008

This paper presents a spatial-level nonparametric multi-focus image fusion technique based on kernel estimates of input image blocks' underlying class-conditional probability density functions. Image fusion is approached as a classification task whose posterior class probabilities, P($wi{\mid}Bikl$), are calculated with likelihood density functions that are estimated from the training patterns. For each of the C input images Ii, the proposed method defines i classes wi and forms the fused image Z(k,l) from a decision map represented by a set of $P{\times}Q$ blocks Bikl whose features maximize the discriminant function based on the Bayesian decision principle. Performance of the proposed technique is evaluated in terms of RMSE and Mutual Information (MI) as the output quality measures. The width of the kernel functions, ${\sigma}$, were made to vary, and different kernels and block sizes were applied in performance evaluation. The proposed scheme is tested with C=2 and C=3 input images and results exhibited good performance.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.85-90
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• 2008

In this paper, we studied on dual reflector adjusted to monopulse antenna system. As a result, when the efficiency of main reflector is more than 70%, The size of reflector is 30 wavelength of maximum frequency and minimum frequency gain is 37.9dBi, and Maximum frequency gain is 38.6dBi. Also, when a radius is D and Focus-distance is $F_e$, a scheme for efficiency improvement of Sub Reflector is to increase the Focus-distance to Diameter Ratio. In this case, Cross polarization in Far field improved and spherical spreading loss in circumference of reflector reduced. The influence of Radiation pattern followed by the side displacement of feed antenna(at $x_sy_s$) is decreased, it is confirmed that performance of scanning is improved.

• Journal of IKEEE
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• v.14 no.3
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• pp.190-198
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• 2010

This paper describes a auto focus piezo actuator driver IC for portable digital camera. The 80[V] DC voltage is generated by a DC-DC converter and supplied to power of piezo moving control circuit. The voltage of piezo actuator needs range -20[V] to 80[V] proportional to 1[Vp-p] input control voltages. The dimensions and number of external parts are minimized in order to get a smaller hardware size. IIC(Inter-IC) interface logic is designed for data interface and it makes debugging easy, test for mass productions. The power consumption is around 40[mW] with supply voltage of 3.6[V]. This device has been fabricated in a 0.6[um] double poly, triple metal 100[V] BCD MOS process and whole chip size is 1600*1500 [$um^2$].

• Journal of the Korean Society for Nondestructive Testing
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• v.19 no.3
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• pp.207-216
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• 1999

A phased array is a multi-element piezoelectric device whose elements are individually excited by electric pulses at programmed delay time. One of the advantages of using phased array in nondestructive evaluation (NDE) application over conventional ultrasonic transducers is their great maneuverability of ultrasonic beam. There are some parameters such as the number and the size of the piezoelectric elements and the inter-element spacing of the elements to design phased array transducer. In this study, the characteristic of ultrasonic beam for phased array transducer due to the variation of the number of elements has been simulated for ultrasonic SH-wave on the basis of Huygen's principle. Ultrasonic beam directivity and focusing due to the change of time delay of each element were discussed due to the change of the number of piezoelectric elements. It was found that ultrasonic beam was much more spreaded and hence its sound pressure was decreased as steering angle of ultrasonic beam was increased. In addition, the ability of ultrasonic bean focusing decreased gradually with the increase of focal length at the same piezoelectric elements. However, the ability of beam focusing was improved as the number of consisting elements was increased.