• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 추계학술대회 논문집
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• pp.738-743
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• 2013

Underwater radiated noise is the key in acoustic stealth performance of modern naval ships. The underwater radiated noise predicted by the hull vibration with radiation efficiency cannot give the information of radiation pattern which is essential to the analysis of detection possibility by enemy and to improve the operational performance of the naval ship. The radiation pattern of underwater radiated noise is able to be obtained with radiation efficiency and radiation direction coefficient. In this paper, a new method to extraction the radiation efficiency and radiation direction coefficient is suggested and proved with the simulation and experiment by using cylindrical shell of 70cm diameter in air.

• 대한지리학회지
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• 제37권4호
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• pp.337-356
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• 2002

청주시 주차장의 공간적 분포 패턴은 상업.업무기능이 집중된 도심에서 동심일 패턴이 주변지역으로 확대되고 있다. 그리고 운영주체별 주차장의 분포는 도심에 공영.민영.건축물 부설 주차장을 중심으로 동심원상으로. 그 인접지역은 공영.건축물 부설 주차장이 분포하고, 선형상으로 공영주차장, 민영.건축물 부설 주차장, 건축물 부설 주차장이 분포하고 있다. 시설구조에 의한 주차장 분포는 청주시 반 이상이 건축물 부설 자주식 주차장을 가지며. 도심에는 건축물 부설 자주식, 노상평면 자주식, 건축물 부설 기계식, 노외평면 자주식 등이 결합된 다양한 주차시설 구조를, 도심 인접지역과 주변지역은 동심원 패턴을 나타내고 있다 또 계약형태별 주차장의 분포는 도심을 중심으로 남서부로는 시간제 지불과 월별 지불의 주차장이. 북동부에는 무료주차장이 주로 분포하고 있다. 이와 같은 주차장의 공간적 분포 패턴은 사업체와 주택의 지역적 분포를 잘 반영하는 것이라고 생각한다.

• Smart Structures and Systems
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• 제15권3호
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• pp.699-715
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• 2015

A modal parameter based damage sensitive feature (DSF) is defined to mimic the relative change in any diagonal element of the stiffness matrix of a model of a structure. The damage assessment is performed in a statistical pattern recognition framework using empirical complementary cumulative distribution functions (ECCDFs) of the DSFs extracted from measured operational vibration response data. Methods are discussed to perform probabilistic structural health assessment with respect to the following questions: (a) "Is there a change in the current state of the structure compared to the baseline state?", (b) "Does the change indicate a localized stiffness reduction or increase?", with the latter representing a situation of retrofitting operations, and (c) "What is the severity of the change in a probabilistic sense?". To identify a range of normal structural variations due to environmental and operational conditions, lower and upper bound ECCDFs are used to define the baseline structural state. Such an approach attempts to decouple "non-damage" related variations from damage induced changes, and account for the unknown environmental/operational conditions of the current state. The damage assessment procedure is discussed using numerical simulations of ambient vibration testing of a bridge deck system, as well as shake table experimental data from a 4-story steel frame.

• 대한기계학회논문집A
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• 제20권8호
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• pp.2468-2479
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• 1996

An upper bound solution is obtained to perform the process analysis of hot strip rolling process. The material flows within the roll bite at various geometries and frictional conditions are obtained from finite element analysis and the typical flow pattern which is necessary to determine the kinematically admissible velocity field is assumed. From the kinematically admissible velocity field, the upper bound energy is calculated and the rolling load, angle of neutral point and forward slip ratio at various operational conditions are obtained from upper bound energy. The process analysis of above mentioned parameters at various operational conditions have provided valuable information which is hard to obtain during rolling operation and the predicted ranges of quantitive values from these analyses lie whthin the bound of actual operational data.

• 한국항행학회논문지
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• 제28권2호
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• pp.178-184
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• 2024

항공기 탑재 레이다는 전술 목적에 따라 다양한 운용 모드를 가지며, 각 모드별 운용 목적에 맞게 탐색 영역을 설정할 수 있도록 설계된다. 일반적인 AESA 레이다는 조종사가 탐색 영역을 지정하면 지정된 영역내 표적을 탐지하기 위해 사전 정의된 탐색빔 그리드에 따라 차례로 탐색빔을 방사하여 표적을 탐지하게 된다. 이때 자항공기의 자세가 변하더라도 사전에 조종사가 탐지하고자 하는 영역을 안정적으로 탐색할 수 있어야 한다. 본 논문은 항공기 탑재 레이다의 공대공 운용 모드에서 탐색 패턴 안정화를 통해 자항공기의 Roll과 Pitch 기동시에도 표적을 안정적으로 탐지할 수 있는 방안에 관한 것으로, 시스템 통합 시험 (SIL; system integration laboratory) 환경에서 자항공기의 기동과 표적을 모의하여 그 성능을 입증하였다.

• 한국군사과학기술학회지
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• 제20권3호
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• pp.328-336
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• 2017

The goal of this study is simulation of optimal search pattern of ships based on performance surface which are reflected underwater environmental. The process is as follows. First, temporal and spatial environmental database are extracted in complex environment and input hull mounted SONAR system parameters. The environmental database and SONAR system parameters are substituted to SONAR equations, and calculate signal excess, detection probability, detection range. And then, the performance surface, which can be used to provide operational insight of SONAR detection performance, are pictorialized. Finally, optimal search pattern of ships are simulated using genetic algorithm based on performance surface. And then, we certify optimal search pattern in various ways.

• 대기
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• 제30권4호
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• pp.405-420
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• 2020

In this study, we investigate the predictability of intraseasonal monthly temperature and precipitation variations using hindcast datasets from eight global circulation models participating in the operational multi-model ensemble (MME) seasonal prediction system of the Asia-Pacific Economic Cooperation Climate Center for the 1983~2010 period. These intraseasonal monthly variations are defined by categorical deterministic analysis. The monthly temperature and precipitation are categorized into above normal (AN), near normal (NN), and below normal (BN) based on the σ-value ± 0.43 after standardization. The nine patterns of intraseasonal monthly variation are defined by considering the changing pattern of the monthly categories for the three consecutive months. A deterministic and a probabilistic analysis are used to define intraseasonal monthly variation for the multi-model consisting of numerous ensemble members. The results show that a pattern (pattern 7), which has the same monthly categories in three consecutive months, is the most frequently occurring pattern in observation regardless of the seasons and variables. Meanwhile, the patterns (e.g., patterns 8 and 9) that have consistently increasing or decreasing trends in three consecutive months, such as BN-NN-AN or AN-NN-BN, occur rarely in observation. The MME and eight individual models generally capture pattern 7 well but rarely capture patterns 8 and 9.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.113-116
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• 2007

The fuel cell which converts directly chemical energy of fuel into electric energy has higher efficiency than the conventional power generation which involves several additional processes. Especially, polymer electrolyte membrane fuel cell (PEMFC) of which the electrolyte is a thin proton conductive polymer membrane is affordable for portable power applications and small-scale distributed power generation including household and small building. It is very important to not only increase the efficiency of FC itself but determine the optimal operation mode. The optimal operational planning of lkW household PEMFC system based on the daily electricity and heat demand patterns was performed. The estimated economic gain was up to 20% by adoption of PEMFC system.

• 해양환경안전학회지
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• 제2권1호
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• pp.143-143
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• 1996

Recent Class requirements and IMO recommendations concerning Hull Strength Monitoring (HSM) have prompted an increasing number of shipowner to adopt monitoring systems on bulk carriers and tanker. Such systems are designed to give warning when stress levels and the frequency and magnitude of ship motions approach levels which require corrective action. When fitted these systems provide enhanced operational safety and efficiency. This paper describes a development beyond the standard BMT HSM system through the integration of stress, motion and radar-based sea state monitoring with powerful, on-board, artificial intelligence (AI) tools. The latter utilises conceptual clustering techniques as an aid to pattern recognition in stress, fatigue. motion and sea state data clusters. This, in turn, provides additional operational guidance for ship's staff. Feedback from applications of the standard BMT HSM and extended HSM systems on board the British Steel Bulk Shipping fleet is described.

• 한국과학교육학회지
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• 제9권1호
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• pp.19-37
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• 1989

The purpose of this study was to investigate the development of logical thinking and scientific reasoning pattern of Korean high school students. To carry out this study subjects were selected about 2,000 Junior high school students, and about 4,100 senior high school students throughout the nation. They were identified as concrete, transitional or formal operational stage with the use of TOLT(the Test of Logical Thinking) by Tobin and Capie(1980), and TOSR(the Test of Scientific Reasoning) by W.A Farmer(1986). This study turned out that more than 76% of Junior high school students were classified as the concrete operational stage and about 44% of senior high school students were classified as the formal operational stage, while about 26% of them were still in the concrete operational level. This study showed that the main factor of the intellectual development of students is learning by the gradual advancement of their grades and especially entrance into the senior high school rather than by the physical growth. This study also showed that there are the take-off stage of the development of logical thinking between fourteen and fifteen years of their ages. Less than 25% of junior high school students were in the formal operational stages which are capable of control of variables, probabilistic, correlation and combinational logic in problem-solving situation, while 33-54% of senior high school students were in the formal operational levels. 38% of junior high school students were in the formal operational stage which is capable of proportional logic, while about 55% of senior high school students were in the formal operational stage. Less than 20% of senior high school students were classified as group of highly capable of scientific reasoning, while more than 23% of them were classified as group of poor capability. It also turned out that there are differences or no differences between male and female students of each school in problem-solving situation regarding each logic approach. These differences were proved to be fluctuating depending on the situations and their grades. The other results of this study is similar to those of other researches such as Tomlinson-Keasey 1972, Coleman 1973, Lawson 1973, Lawson and Renner 1974, Neimark 1975, Han 1982, and Kim 1989.