• 대한건축학회논문집:계획계
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• 제35권1호
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• pp.37-46
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• 2019

The energy of the building is influenced by the user 's activity due to the population, society, and economic characteristics of the building user. In order to obtain accurate energy information, the difference in the amount of energy consumption by the activities and characteristics of building users should be identified. The purpose of the study is to identify the difference in the amount of energy consumption by the user's activities in the same building, and to analyse the relationship between user's activities and demographic, social and economic characteristics. For research, energy simulation is performed based on actual user activity schedule. The results of the simulation were clustered by using K-Means clustering, a machine learning technique. As a result, four types of users were derived based on the amount of energy consumption. The more energy used in a cluster, the lower the user's income level and older. The longer a user's indoor activity times, the higher the energy use, and these activities relate to the user's characteristics. There is more than twice the difference between the group that uses the least energy consumption and the group that uses the most energy consumption.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권7호
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• pp.1293-1310
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• 2011

A simple modification of well known Low Energy Adaptive Clustering Hierarchy (LEACH) protocol is proposed to exploit cooperative diversity. Instead of selecting a single cluster-head, we propose M cluster-heads in each cluster to obtain a diversity of order M. The cluster-heads gather data from all the sensor nodes within the cluster using same technique as LEACH. Cluster-heads transmit gathered data cooperatively towards the destination or higher order cluster-head. We propose a code combining based cooperative diversity protocol which is similar to coded cooperation that maximizes the performance of the proposed cooperative LEACH protocol. The implementation of the proposed cooperative strategy is analyzed. We develop the upper bounds on bit error rate (BER) and frame error rate (FER) for our proposal. Space time block codes (STBC) are also a suitable candidate for our proposal. In this paper, we argue that the STBC performs worse than the code combining cooperation.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.116-119
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• 2005

As to the synthetical estimation of land covering parameters or the compounded land covering classification for multi-resolution satellite data, former researches mainly adopted linear or nonlinear regression models to describe the regression relationship of land covering parameters caused by the degradation of spatial resolution, in order to improve the retrieval accuracy of global land covering parameters based on 1;he lower resolution satellite data. However, these methods can't authentically represent the complementary characteristics of spatial resolutions among different satellite data at arithmetic level. To resolve the problem above, a new compounded land covering classification method at arithmetic level for multi-resolution satellite data is proposed in this .paper. Firstly, on the basis of unsupervised clustering analysis of the higher resolution satellite data, the likelihood distribution scatterplot of each cover type is obtained according to multiple-to-single spatial correspondence between the higher and lower resolution satellite data in some local test regions, then Parzen window approach is adopted to derive the real likelihood functions from the scatterplots, and finally the likelihood functions are extended from the local test regions to the full covering area of the lower resolution satellite data and the global covering area of the lower resolution satellite is classified under the maximum likelihood rule. Some experimental results indicate that this proposed compounded method can improve the classification accuracy of large-scale lower resolution satellite data with the support of some local-area higher resolution satellite data.

• 정보처리학회논문지B
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• 제10B권3호
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• pp.287-296
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• 2003

추천 시스템에 있어서 협력적 필터링 기술은 많은 연구가 되고 있다. 그러나 협력적 필터링 기술을 이용한 추천 시스템은 초기 평가 문제와 희박성 문제가 발생한다. 이를 해결하기 위해서 본 논문에서는 선호도 재 계산을 위한 연관 사용자 군집과 베이지안 추정치를 이용한 사용자 선호도 예측 방법을 제안한다. 제안한 방법에서는 협력적 필터링 시스템에서 아이템의 속성을 고려하지 않는 단점을 보완하기 위해서 선호도에 가장 크게 영향을 미치는 대표 장르를 추출하여 유사한 이웃을 찾아 낼 때 예측에 이용하는 Representative Attribute-Neighborhood 방법을 사용한다. 협력적 필터링의 알고리즘에 군집 아이템 백터 내의 특정 아이템의 선호도를 재계산 하기 위한 연관 사용자 군집 분석을 적용하여 성능 향상을 하였다. 또 초기 평가 문제와 희박성 문제를 해결하기 위하여 Association Rule Hypergraph Partitioning 알고리즘을 사용하여 사용자를 장르별로 군집한다. 새로운 사용자는 Naive Bayes 분류자에 의해 이들 장르 중 하나로 분류된다. 또한, 분류된 장르 내에 속한 사용자들과 새로운 사용자의 유사도를 구하기 위해 Naive Bayes 학습을 통해 사용자가 평가한 아이템에 추정치를 달리 부여한다. 추정치가 부여된 선호도를 피어슨 상관 관계에 적용할 경우 결측치(Missing Value)로 인한 예측의 오류를 적게하여 예측의 정확도를 높일 수 있다. 제안된 방법은 기존의 방법보다 높은 성능을 나타냄을 보인다.

• 대한교통학회지
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• 제21권5호
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• pp.7-18
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• 2003

해운 및 항만물류 환경의 변화로 말미암아, 현재 아시아 항만들은 치열한 경쟁상황에 놓여 있으며, 권역내 거대중심항이 되기 위한 집중적인 투자와 체계적인 전략수립을 추진하고 있다. 따라서, 현시점에서 아시아 항만의 경쟁력을 분석/분류하고 평가하는 것은 부산항이 속해 있는 우리나라의 입장에서 매우 중요한 연구임에 틀림없다. 그러나, 이와 관련하여 다수의 기존연구가 수행되어 왔지만, 연구의 대상을 아시아 항만을 뛰어넘어 세계 주요항만으로 하거나, 게다가 어떤 객관적인 기준이 없이 단순히 해당시점에 널리 회자되고 있는 항만들을 대상으로 하여, 부산항의 입장에서 실질적이고 명확한 분석지표로 활용되기 곤란한 연구가 대부분이었다. 또한 연구의 방법론적 측면에서 기존연구들은 크게 AHP(Analytical Hierarchy Process)법과 같은 계층평가알고리즘과 군집분석법(Clustering analysis)을 이용하여 항만의 순위를 정하거나 항만을 동일군으로 군집화하여 분석을 행하였으나, 이 두 가지 방법은 알고리즘상 고유의 문제점을 가지고 있어, 분석법에 따른 해석의 편중이 빈번히 발생하였다. 본 연구의 목적은 항만인프라와 관련한 경쟁력요소를 중심으로 아시아 주요항만을 경쟁수준별로 체계적으로 분류하는 것이다. 특히, 기존연구의 문제점을 극복하기 위해 본 연구에서는 객관적인 지표에 의거하여 아시아 주요 대상 항만을 선정했다. 게다가 연구 방법론의 측면에서 기존의 군집분석법의 문제점을 보완하기 위해서 FCM(Fuzzy C-means)기법을 이용하여 분석을 수행하였다. 분석결과, 아시아 16개 주요 항만들 중 10개 항만이 독자적인 위상을 가지고 4가지 항만군을 형성하고 있었으며, 나머지 6개항만은 다른 10개 항만들과 같은 독자적인 특성을 보이지 않아, 현시점에서 하나의 군집으로 명확히 분류될 수 없는 것으로 분석되었다. 게다가, 독자적 위상을 가지고 있지 않은 항만들 중, 몇 개의 항만은 향후 변화의 가능성이 매우 높고 그리고 아시아 항만전체의 판도변화의 주역으로 발전할 가능성도 높은 항만으로 분석되었다. 이러한 분석결과는 아시아 항만의 판도의 고찰과 더불어 다각도로 고찰되었으며, 그러한 고찰결과에 기초하여 끝으로 부산항의 현재위상과 대략적인 앞으로의 방향이 제시되었다.

• 천문학회보
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• 제46권2호
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• pp.72.3-73
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• 2021

Baryon Acoustic Oscillations (BAO) are caused by acoustic density waves in the early universe and act as a standard ruler in the clustering pattern of galaxies in the late Universe. Measuring the BAO feature in the 2-point correlation function of a sample of galaxies allows us to estimate cosmological distances to the galaxies mean redshift, , which is important for testing and constraining the cosmology model. The BAO feature is also expected to appear in the higher order statistics. In this work we measure the generalized spatial N-point point correlation functions up to 4th order. We made measurements of the 2, 3, and 4-point correlation functions in the SDSS-III DR12 CMASS data, comprising of 777,202 galaxies. The errors and covariances matrices were estimated from 500 mock catalogues. We created a theoretical model for these statistics by measuring the N-point functions in halo catalogues produced by the approximate Lagrangian perturbation theory based simulation code, PINOCCHIO. We created simulations using initial conditions with and without the BAO feature. We find that the BAO is detected to high significance up to the 4-point correlation function.

• 열처리공학회지
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• 제7권1호
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• pp.44-52
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• 1994

In order to investigate the effect of tempring treatment on the mechanical properties of ausformed martensite in Fe-30%Ni-0.35%C alloy, the hardness, yield strength and elongation were examined by tensile test. 1. The strength of deformed austenite in Fe-30%Ni-0.35%C alloy was increased due to the work hardening induced from the dislocation density increased during deformation. The strength of ausformed martensite was increased because of defects inherited from deformed austenite by martensitic transformation. 2. The ductility of ausformed martensite was shown a nearly constant values independent of deformation degrees because of the interaction of multiple factors such as increased retained austenite, formation of void and decrement of twin in ausformed martensite. 3. The strength of ausformed martensite by tempering treatment was shown a little decrement up to $340^{\circ}C$, especially showed remarkable softening resistance in higher deformation degrees. 4. Virgin martensite and ausformed martensite were shown a maximum yield strength by clustering in tempering at $100^{\circ}C$ and above $100^{\circ}C$, yield strength was very small decreased due to the decrement of solute carbon by the destruction of clustering. 5. The decomposition of retained austenite was not shown up to $450^{\circ}C$ in ausformed martensite with tempering treatment, and the matrix was rapidly softening because of the decomposition of martensite and the formation of reversed austenite with tempering above $400^{\circ}C$.

• 국토계획
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• 제53권7호
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• pp.109-126
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• 2018

The purpose of this study is to identify the spatial types for thermal environment improvement considering heat flux and its spatial context through empirical orthodox formulas. First, k-means clustering was used to classify values of three kinds of heat flux - latent, sensible and storage heat. Next, from the k-means clustering, we defined a type of thermal environment (type LHL) where improvement is needed for more comfortable and pleasant thermal environment in the city, among the eight types. Lastly, we compared and analyzed the characteristics of each classified thermal environmental types based on land cover types. From the study, we found that the ratio of impervious surfaces, roads, and buildings of the type LHL is higher than those of the type HLH (relatively thermal comfort environment). In order to improve the thermal environment, the following contents are proposed to urban planners and designers depending on the results of the study. a) Increase the green zone rate by 10% to reduce sensible heat; b) Reduce the percentage of impermeable surfaces and roads by 10% ; c) Latent heat increases when water and green spaces are expanded. This study will help to establish a minimum criterion for a land cover rate for the improvement of the urban thermal environment and a standard index for the thermal environmental improvement can be derived.

• Smart Structures and Systems
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• 제20권1호
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• pp.61-74
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• 2017

One of the most reliable and simplest tools for structural vibration control in civil engineering is Tuned Mass Damper, TMD. Provided that the frequency and damping parameters of these dampers are tuned appropriately, they can reduce the vibrations of the structure through their generated inertia forces, as they vibrate continuously. To achieve the optimal parameters of TMD, many different methods have been provided so far. In old approaches, some formulas have been offered based on simplifying models and their applied loadings while novel procedures need to model structures completely in order to obtain TMD parameters. In this paper, with regard to the nonlinear decision-making of fuzzy systems and their enough ability to cope with different unreliability, a method is proposed. Furthermore, by taking advantage of both old and new methods a fuzzy system is designed to be operational and reduce uncertainties related to models and applied loads. To design fuzzy system, it is required to gain data on structures and optimum parameters of TMDs corresponding to these structures. This information is obtained through modeling MDOF systems with various numbers of stories subjected to far and near field earthquakes. The design of the fuzzy systems is performed by three methods: look-up table, the data space grid-partitioning, and clustering. After that, rule weights of Mamdani fuzzy system using the look-up table are optimized through genetic algorithm and rule weights of Sugeno fuzzy system designed based on grid-partitioning methods and clustering data are optimized through ANFIS (Adaptive Neuro-Fuzzy Inference System). By comparing these methods, it is observed that the fuzzy system technique based on data clustering has an efficient function to predict the optimal parameters of TMDs. In this method, average of errors in estimating frequency and damping ratio is close to zero. Also, standard deviation of frequency errors and damping ratio errors decrease by 78% and 4.1% respectively in comparison with the look-up table method. While, this reductions compared to the grid partitioning method are 2.2% and 1.8% respectively. In this research, TMD parameters are estimated for a 15-degree of freedom structure based on designed fuzzy system and are compared to parameters obtained from the genetic algorithm and empirical relations. The progress up to 1.9% and 2% under far-field earthquakes and 0.4% and 2.2% under near-field earthquakes is obtained in decreasing respectively roof maximum displacement and its RMS ratio through fuzzy system method compared to those obtained by empirical relations.

• 한국음향학회지
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• 제28권6호
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• pp.572-577
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• 2009

대용량 음성 DB를 사용하는 음편접합 TTS는 부가적인 신호처리 기술을 거의 사용하지 않고, 문맥을 반영하는 여러 합성유닛들을 결합해 합성음을 생성하기 때문에 높은 자연성을 가진다는 장점이 있다. 중복되는 음편의 감량을 위해서 음성인식분야에서 사용되는 결정트리 기반의 트라이폰 군집화 알고리즘을 사용할 수 있지만 음편 내의 음향적 천이 특성을 반영하기가 어렵고 문맥질의 적용이 체계적이지 못하여 TTS에 바로 적용하기 어렵다. 본 논문에서는 DB감량을 위해 결정 트리 기반의 새로운 음소 군집화 방법을 제안한다. 먼저 음편의 처음, 중간, 끝 3프레임의 각 13차 MFCC벡터를 통합한 39차의 벡터로 음편내의 변이성과 연결성을 표현한다. 결정 트리의 상위부분에서는 포괄적인 문맥질의를 하위부분에서는 세부적인 문맥질의를 적용시켰다. 그리고 기존 결정트리 시스템과 제안된 시스템과의 성능평가를 위하여 평가용 트라이폰 모델의 음편과 트리에서 탐색한 트라이폰 모델의 음편들 간의 음향적 유사도를 DTW를 적용하여 계산하였다. 실험결과 제안된 방법을 사용할 경우 전체 음성DB의 크기를 23%로 줄일 수 있었고, 음향적 유사도가 높은 음편을 선택함을 보이므로 향후 소용량 DB TTS에 적용 가능성을 보였다.