• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.3 no.1
• /
• pp.35-41
• /
• 1983

The purpose of this study is to provide a method of estimating the frequency of flood magnitudes in ungauged station. Six major station are selected for this study in the Geum River system. For each gauging station in the basin, T-year flood is determined by Weibull plotting position. The derivation of the flood frequency formulae is performed on the basis of estimating method of floods with using the hydrological and geomorphical factors developed by U.S. Geological Survey. It is found that the model in this study can be applied to flood flow estimation of ungauged station in the Geum River basin because the mean characteristics of flood flow is used for the basin.

• The Korean Journal of Applied Statistics
• /
• v.25 no.1
• /
• pp.81-87
• /
• 2012

A continuous time risk model is considered, where the premium rate is constant and the claims form a compound Poisson process. We assume that an injection is made, which is an immediate increase of the surplus up to level u > 0 (initial level), when the level of the surplus goes below ${\tau}$(0 < ${\tau}$ < u). We derive the formula of the ruin probability of the surplus by establishing an integro-differential equation and show that an explicit formula for the ruin probability can be obtained when the amounts of claims independently follow an exponential distribution.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.26 no.4
• /
• pp.406-411
• /
• 2016

The natural frequencies and mode shapes of a system composed of subsystems on a supporting structure have been derived approximately. The system is modeled as a discrete system, and it is assumed that the masses of subsystems are much smaller than the mass of a supporting structure. It has been found that the fundamental frequency corresponds to the supporting structure, and each higher frequency corresponds to each subsystem. A relation between the vibration amplitudes of the supporting structure and subsystems is also derived for the case when the supporting structure is excited by a harmonic force.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2012.05a
• /
• pp.510-510
• /
• 2012

최근 4대강 살리기 등 하천 개발 사업으로 인한 하천환경의 변화로 하도 내 유사의 세굴 및 퇴적 문제가 제기되고 있으며 이에 대한 대책수립이 요구되고 있는 실정이다. 국외의 경우 이미 수제와 같은 수공구조물의 설계 가이드와 유로 확보 및 하도 안정화를 위한 목적의 수제가 실제 하천에 적용된 사례를 확인할 수 있으며 경험적 공식 등을 통해 이미 실용화 단계에 있다. 그러나 국내의 경우 소수의 수제 설치 등 제한적인 연구만이 진행되고 있을 뿐 하도 안정화를 위한 적절한 기술 개발이 미흡한 실정이다. 본 연구에서는 하도안정화를 위한 구조적 대책의 일환으로 이동상 수리모형 실험을 통해 단일 및 연속수제를 이용함에 있어 수제 설치에 따른 하상변화의 특성을 지배하는 매개변수(수심, 후루이드 수, 유속 등)를 검토하였다. 연구 결과 후루이드 수와 수심 뿐만 아니라 평균 유속 와 한계유속 $V_r$을 무차원화한 $V/V_{cr}$ 값이 하상 변동 양상에 지배적인 영향을 미친다는 사실을 확인하였다. 수제주변의 정량적 세굴 및 퇴적 깊이와 범위는 물론 수제가 수제부 하류에 미치는 하상 변화의 영향 범위를 지배하는 인자들의 상관관계를 유도하였다. 본 연구에서 확인한 수제 설치 시 하상변동 특성을 지배하는 주요인자들과 이들의 상관관계는 하상의 안정성 확보 및 수제 설계 가이드라인 수립을 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Korean Journal of Optics and Photonics
• /
• v.14 no.6
• /
• pp.583-587
• /
• 2003

In this paper, the optimal performance of optical second-order polarization mode dispersion (PMD) compensation has been investigated theoretically in terms of minimization of the root-mean-square (RMS) pulse broadening. The optimal compensation vector in feedforward-type second-order PMD compensation has been derived, and the RMS pulse broadening factor after the optimal second-order PMD compensation has been analytically calculated. The calculated result has been compared with the previously reported simulation result where numerically optimized feedback scheme was adopted. They are in good agreement, which verifies the validity of the derivation. The investigation in this work will form the basis for the implementation of the feed-forward-type second-order PMD compensation.

• Journal of Korea Society of Industrial Information Systems
• /
• v.14 no.1
• /
• pp.9-16
• /
• 2009

In this paper, a method is proposed for the analysis of radiowave receiving characteristics of an ammunition with electric detonator. In this method, an ammunition with electric detonator is modelled as a receiving antenna with its gain obtained by computer simulation or measurement. The induced radiowave power is obtained by inserting the gain of the electric detonator in the antenna coupling formula. Radiowave receiving characteristics at very close distances are obtained by Treasuring the transmission coefficient between a half-wave dipole and the electric detonator model. Radiowave receiving characteristics of the electric detonator in a 105mm tank ammunition are obtained using the proposed method and the safety of the 900 MHz RFID reader on the detonator is assessed.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2021.06a
• /
• pp.256-256
• /
• 2021

Saint-Venant 방정식은 수평규모가 수심규모보다 큰 천수흐름을 기술하는 수리동역학 모형으로 지난 수십년간 공학적 분야에서 널리 이용되어 왔다. 최근에도 기후변화에 따른 도시 홍수의 위기 증대로 홍수위기관리의 관심이 높아짐에 따라 홍수파(flood wave), 도시침수(urban inundation), 돌발홍수(flash flood) 등의 신속한 예측을 위한 Saint-Venant 방정식의 연구가 활발히 진행되고 있다. 그러나 도시와 같은 인공구조물이 즐비한 상황에서 천수흐름을 해석하는 고전적인 수치해법들은 다양한 불연속 지형들의 존재로 인하여 불안정하며 지배방정식의 정해로 수치해가 잘 수렴하지 않는 문제가 있다. 지난 수년간 이를 해결하기 위해 불연속한 지형을 안정적으로 해결할 수 있는 수치기법의 연구가 진행되어 왔으나, 정해로의 수렴성, 정확성에 관하여 연구가 부족한 실정이다. 본 연구는 수치해법의 주요 구조를 구성하는 Saint-Venant 방정식의 불연속한 지형조건에 대한 리만 문제의 정해를 연구하였다. 쌍곡선형 시스템의 특징을 고려하여 요소파들(elementary waves)의 공식을 유도하였는데, 질량과 에너지의 보존법칙에 위배되지 않으며 운동량이송부의 비선형성과 지형의 불연속에 의한 비엄격성을 고려할 수 있는 조건을 제시하였다. 또한, 유도된 요소파들을 바탕으로 L-M & R-M 커브이론(Han et al. 2014)을 사용할 수 있는 조건과 당위성을 증명하였고, 이를 바탕으로 Saint-Venant 방정식의 정해법을 구성하였다. 리만문제의 다양한 초기조건들을 바탕으로 모든 경우의 정해 구조를 조사하였고, 이를 통해 불연속 지형에 대한 Saint-Venant 지배방정식의 정해가 다수해를 갖을 수 있음을 보였으며, 이를 근사할 수 있는 수치기법의 전략을 소개하였다.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.27 no.4
• /
• pp.457-465
• /
• 2024

The Remote Control Munition System is a anti-personnel munitions system to replace land mines that are hard to retrieve and can inflict damage on friendly forces and civilians. As operating environments and methods change, quality improvement is necessary to ensure appropriate durability. Therefore, corrosion resistance evaluation was performed according to the surface treatment of ALDC12, the main assembly material. We conduct the potentiodynamic polarization, cyclic corrosion test to perform analysis on corrosion behavior. Additionally, we try to observe the pitting on the surface through SEM analysis. In conclusion, among the three surface treatments, Anodizing surface treatment is judged to be the most suitable for corrosion durability in a field environment.

• Journal of Dairy Science and Biotechnology
• /
• v.35 no.1
• /
• pp.39-45
• /
• 2017

The market for lactose-hydrolyzed milk is growing due to an increased awareness of lactose intolerance, and increased market interest for modified milk with health claims. The aim of this study was to compare the quality characteristics of 2% lactose-hydrolyzed milk with its lactose hydrolysis rate, with the goal of applying the method to dairy product monitoring in the future. We observed that the freezing point of milk significantly decreased with increasing lactose hydrolysis rate. A linear relationship was found between lactose concentration and freezing point, following the equation (y=-50.416x + 767.91). However, no significant changes were observed in other physicochemical properties of the milk (pH, titratable acidity, total solids and color) (p<0.05). In conclusion, we could predict the residual lactose content quickly and easily in 2% low fat milk by measuring its freezing point. This could represent an easy means for assessing the lactose hydrolysis rate of dairy products.

• The KIPS Transactions:PartC
• /
• v.12C no.5 s.101
• /
• pp.673-678
• /
• 2005

Alamouti STC (Space-Time Code) is a part of the UMTS-WCDMA standard. However, up to the best of our knowledge no closed-form BER formula for this famous code exists. Evaluating its performance through simulations is time-consuming and therefore, there should be analytical BER graphs to serve as a reference which are derived in this paper for coherently BPSK-modulated data.