• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.111.2-111.2
• /
• 2010

삼상슬러리 기포탑 반응기의 설계 및 Scale-up을 위하여 기포탑의 직경변화에 따른 기체-슬러리 계면에서의 물질전달 현상의 Similarity를 검토하고, 기체-슬러리 계면에서의 물질전달 현상과 슬러리 기포탑 반응기의 운전변수 및 반응물들의 물성들과의 연관성을 고찰하기 위하여 삼상슬러리 기포탑의 물질전달계(System)에서 주요 파라메타를 도출하였으며, 이들 파라메터들을 이용하여 슬러리 기포탑반응기의 물질전달 Scaling을 검토하였다. 물질전달계의 주요제어인자로는 기체-액체 부피물질전달계수($k_La$), 슬러리상의 확산도($D_{SL}$), 기포탑의 직경(D), 기포탑 반응기에 유입되는 기체의 유입속도($U_G$), 기포탑 반응기 내부의 연속상인 슬러리상의 표면장력(${\sigma}_{SL}$), 슬러리상과 기체상간의 밀도차(${\rho}_{SL}-{\rho}_G$) 그리고 슬러리상의 점도(${\mu}_{SL}$)등 슬러리 상의 물성을 선정하였으며 중력가속도(g)를 선정하였다. 물질전달계의 Scling을 검토하기위하여 이를 재구성하였으며 기포탑 반응기의 구조와 직경이 변화함에 따라 이들 무차원군의 변화양상을 고찰하였다. 실험적으로 측정된 물질전달계수와 Scaling에 의해 예측된 물질전달계수를 비교 검토함으로써 본 연구의 Correlation의 적용범위를 제시하였다.

• 응용통계연구
• /
• 제25권4호
• /
• pp.613-620
• /
• 2012

In most cases of multidimensional scaling(MDS), the distances or dissimilarities among units are assumed to be symmetric. Thus, it is not an easy task to deal with asymmetric distances. Asymmetric MDS developed so far face difficulties in the interpretation of results. This study proposes a much simpler asymmetric MDS, that utilizes the notion of "altitude". The analogy arises in mountaineering: It is easier (more difficult) to move from the higher (lower) point to the lower (higher). The idea is formulated as a quantification problem, in which the disparity of distances is maximally related to the altitude difference. The proposed method is demonstrated in three examples, in which the altitudes are visualized by rainbow colors to ease the interpretability of users.

• 대한기계학회논문집B
• /
• 제30권9호
• /
• pp.825-833
• /
• 2006

To investigate the moderator coolability for CANDU-6 reactors, a test facility (HU-KINS) has been manufactured as a 1/8 scaled-down of a calandria tank. In the design of the test facility, a scaling law was developed in such a way to consider the thermal-hydraulic characteristics of a CANDU-6 moderator. The proposed scaling law takes into consideration of the energy conservation, the dynamic similitude such as dimensionless numbers, Archimedes number (Ar) and Reynolds number (Re), and thermal-hydraulic properties similitude. Using this proposed scaling law, the thermal-hydraulic scaling analyses of similar test facilities such as the SPEL (1/10 scale) and the STERN (1/4 scale), have been identified. As a result, in the case of the SPEL, while the energy conservation is well defined, the similarities of Ar and the heat density are not well considered. As for the similarity of the STERN, while both the energy conservation and the characteristics of Ar are well defined, the heat density is not. In the meanwhile, the HU-KINS test facility with 1/8 length scaled-down is well similitude in compliance with all similarities of the energy conservation, the fluid dynamics and thermal-hydraulic properties. To verify the adequacy of the similarities in terms of thermal-hydraulics, a computational fluid dynamic (CFD) analysis has been conducted using the CFX-5 code. As the results of the CFD analyses, the predicted flow patterns and variation of axial properties inside the calandria tank are well consistant with those of previous studies performed with FLUENT and this implies that the present scaling method is acceptable.

• 한국연소학회지
• /
• 제5권2호
• /
• pp.51-62
• /
• 2000

The relationship among the flame radiation, NOx emissions, residence time, and global strain rate are examined for turbulent non-premixed jet flames with wide variations in coaxial air conditions. Measurements of NOx emission, flame geometry and flame radiation were made to explain the NOx emission scaling based on global parameters such as flame residence time, global strain rate, and radiant fraction. The overall 1/2-power scaling is observed in coaxial air flames, irrespective of coaxial air conditions, but the degree of deviation from the 1/2-slope curve in each case differs from one another. From the comparison between the results of pure hydrogen flames and those of helium diluted hydrogen flames, it is observed that flame radiation plays a significant role in pure hydrogen flames with coaxial air and the deviation from 1/2-power scaling may be explained in two reasons: the difference in the flame radiation and the difference in jet similarity in coaxial air flames. From the radiation measurements, more detailed explanations on these deviations were suggested.

• 감성과학
• /
• 제26권2호
• /
• pp.25-38
• /
• 2023

정서표상에 대한 논의 중 첫 번째는 정서가 차원에서의 정서표상, 두 번째는 감각양상에 따른 정서표상을 설명하는 것이다. 선행연구에서는 정서표상을 설명하기 위해 정서가 모델(부호 정서가, 비부호 정서가), 감각양상에 따른 정서표상 모델(감각보편성, 감각특징성)들이 제시되었다. 본 연구에서는 최근에 등장한 ASMR을 이용하여 기존 연구에서 제시된 모델들을 비교하여 어떠한 모델이 정서표상을 잘 설명하는지 확인하고자 하였다. 본 연구에서 사용한 자료는 Kim & Kim(2022)에서 수집한 3개의 정서유형(부정, 중립, 긍정) 및 2개의 감각양상(청각, 시청각)으로 구분된 ASMR 자극에 대한 정서평정자료를 사용하였다. 이후, 해당 자료에 대한 다차원척도법, 표상 유사성 분석 및 이원 변량분석, 다중회귀분석 및 이원 변량분석을 실시하였다. 다차원척도법 결과, 비부호 정서가에 비해 부호 정서가, 감각특징성에 비해 감각보편성에서 자극의 정서유형 간 구분이 잘 이루어졌다. 다차원척도법 결과와 유사하게, 표상 유사성 분석 및 다중회귀분석 결과 또한 비부호 정서가에 비해 부호 정서가, 감각특징성에 비해 감각보편성이 유의하게 정서표상을 잘 설명하였다. 이러한 결과는 정서가 모델 중 1차원의 양극단에 긍정과 부정이 위치하는 모델이 ASMR에 대한 정서표상을 잘 설명하며, 감각양상과 상관없이 정서표상이 일관적임을 시사한다.

• Journal of Communications and Networks
• /
• 제3권4호
• /
• pp.383-395
• /
• 2001

Recent measurement and simulation studies have revealed that wide area network traffic displays complex statistical characteristics-possibly multifractal scaling-on fine timescales, in addition to the well-known properly of self-similar scaling on coarser timescales. In this paper we investigate the performance and network engineering significance of these fine timescale features using measured TCP anti MPEG2 video traces, queueing simulations and analytical arguments. We demonstrate that the fine timescale features can affect performance substantially at low and intermediate utilizations, while the longer timescale self-similarity is important at intermediate and high utilizations. We relate the fine timescale structure in the measured TCP traces to flow controls, and show that UDP traffic-which is not flow controlled-lacks such fine timescale structure. Likewise we relate the fine timescale structure in video MPEG2 traces to sub-frame encoding. We show that it is possibly to construct a relatively parsimonious multi-fractal cascade model of fine timescale features that matches the queueing performance of both the TCP and video traces. We outline an analytical method ta estimate performance for traffic that is self-similar on coarse timescales and multi-fractal on fine timescales, and show that the engineering problem of setting safe operating points for planning or admission controls can be significantly influenced by fine timescale fluctuations in network traffic. The work reported here can be used to model the relevant characteristics of wide area traffic across a full range of engineering timescales, and can be the basis of more accurate network performance analysis and engineering.

• 한국지역지리학회지
• /
• 제11권4호
• /
• pp.497-510
• /
• 2005

본 연구는 충청권역 5개 온천관광지를 대상으로 다차원 척도법을 활용하여 이미지 유사성, 속성인식도 및 선호도를 분석하였으며 결과는 다음과 같다. 첫째, 온천관광지의 이미지 유사성 분석 결과, "수안보와 온양" 그리고 "도고와 아산"이 각각 유사한 이미지 그룹을 형성하고 있으며, 유성은 다른 이미지를 갖고 있다. 둘째, 온천관광지 속성인식도 분석 결과, 유성은 '온천전통' 속성을 경쟁 온천관광지와 비교할 때 가장 많이 반영하고 있으며, 온양은 '부대시설' 도고는 '이용비용', 그리고 수안보는 '부대시설', '고객서비스'와 '접근성'의 속성을 비교적 많이 반영하는 것으로 나타났다. '온천수질'과 '체험활동'은 모든 온천관광지에서 반영되지 않고 있는 속성으로 나타났다. 셋째, 관광객 유형별 온천 관광지 선호도 분석 결과, 패키지 관광객은 유성을, 개별, 수학여행, 가족, 연수 관광객은 수안보를, 그리고 단체 관광객은 도고를 가장 선호하는 것으로 나타났다.

• 한국의상디자인학회지
• /
• 제13권4호
• /
• pp.1-14
• /
• 2011

This study is to analyze the image similarity and the preference for clothing stores in the 6 giant discount chains in Daejeon. The survey for this study was based on the questionnaires accomplished by 257 people through the multidimensional scaling. The results are as follows First, 6 clothing stores had 4 image groups located in 4 coordinates. CW(Costco Wholesale), NH(Nonghyup Hanaro-Mart), and SZ(Save Zone) had a similar distinct image, while HP(Home Plus) and EM(E-Mart), and LM(Lotte-Malt) also had similar differentiated images. Second, according to the preference analysis in terms of demographic characteristic, NH had the lowest preference from the people of all the different ages, while SZ had the highest. HP, EM, CW, and LM had their own preference in the following order: in the thirties, forties, and over fifties. Meanwhile, relatively, SZ is preferred by the people in their twenties and people over age fifty liked CW more. Third, according to the analysis of the preference for clothing stores in the giant discount chains in terms of educational background, clothing consumers who had high school degrees preferred NH and LM, people with 2 year college degrees liked HP and EM more, while 4-year college graduates and people with higher education had preference for SZ. Finally, according to the preference analysis in terms of income level, higher income groups preferred SZ and CW and lower income groups liked LH and LM more, while HP and EM had high preference from all kinds of income groups.

• 한국해양공학회지
• /
• 제31권4호
• /
• pp.257-265
• /
• 2017

In this study, a series of numerical simulations was conducted in order to design a truncated mooring line with a static similarity to the prototype. A finite element method based on minimizing the potential energy was utilized to describe the dynamics of mooring lines. The prototype mooring lines considered were installed at a water depth of 1,000 m, whereas the KRISO ocean engineering basin (OEB) in Daejeon has a water depth of 3.2 m, which represents 192 m using a scaling of 1:60. First, an investigation for the design of the truncated mooring line was carried out to match the static characteristics of the KRISO Daejeon OEB environment. Then, the same procedure was performed with the KRISO new deepwater ocean engineering basin (DOEB) that is under construction in Busan. This new facility has a water depth of 15 m, which reflects a real scale depth of 900 m considering the 1:60 scaling factor. A finite element method was used to model the mooring line dynamics. It was found that the targeted truncated mooring line could not be designed under the circumstances of the KRISO OEB with any material properties, whereas several mooring lines were easily matched to the prototype under the circumstances of the KRISO DOEB.

• Wind and Structures
• /
• 제38권4호
• /
• pp.261-275
• /
• 2024

Before performing an experimental study on the downburst-generated wave, it is necessary to examine the scale effects and corresponding corrections or compensations. Analysis of similarity is conducted to conclude the non-dimensional force ratios that account for the dynamic similarity in the interaction of downburst with wave between the prototype and the scale model, along with the corresponding scale factors. The fractional volume of fluid (VOF) method in association with the impinging jet model is employed to explore the characteristics of the downburst-generated wave numerically, and the validity of the proposed scaling method is verified. The study shows that the location of the maximum radial wind velocity in a downburst-wave field is a little higher than that identified in a downburst over the land, which might be attributed to the presence of the wave which changes the roughness of the underlying surface of the downburst. The impinging airflow would generate a concavity in the free surface of the water around the stagnation point of the downburst, with a diameter of about two times the jet diameter (D_jet). The maximum wave height appears at the location of 1.5D_jet from the stagnation point. Reynolds number has an insignificant influence on the scale effects, in accordance with the numerical investigation of the 30 scale models with the Reynolds number varying from 3.85 × 10⁴ to 7.30 × 10⁹. The ratio of the inertial force of air to the gravitational force of water, which is denoted by G, is found to be the most significant factor that would affect the interaction of downburst with wave. For the correction or compensation of the scale effects, fitting curves for the measures of the downburst-wave field (e.g., wind profile, significant wave height), along with the corresponding equations, are presented as a function of the parameter G.