• 한국수학교육학회지시리즈B:순수및응용수학
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• 제29권2호
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• pp.179-188
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• 2022

In this paper we investigate the Hyers-Ulam stability of the s-variable additive and l-variable quadratic functional equations of the form $$f\(\sum\limits_{i=1}^{s}x_i\)+\sum\limits_{j=1}^{s}f\(-sx_j+\sum\limits_{i=1,i{\neq}j}^{s}x_i\)=0$$ and $$f\(\sum\limits_{i=1}^{l}x_i\)+\sum\limits_{j=1}^{l}f\(-lx_j+\sum\limits_{i=1,i{\neq}j}^{l}x_i\)=(l+1)$$$\sum\limits_{i=1,i{\neq}j}^{l}f(x_i-x_j)+(l+1)\sum\limits_{i=1}^{l}f(x_i)$ (s, l ∈ N, s, l ≥ 3) in quasi-Banach spaces.

• 천문학회지
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• 제49권5호
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• pp.209-223
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• 2016

We present analyses of ~1250 variable sources identified in a 20 square degree field toward NGC 2784 by the KMTNet Supernova Program. We categorize the variable sources into three groups based on their B-band variability. The first group consists of 31 high variability sources with their B-band RMS variability greater than 0.3 magnitudes. The second group of medium variability contains 265 sources with RMS variability between 0.05 and 0.3 magnitudes. The remaining 951 sources belong to the third group of low variability with an RMS variability smaller than 0.05 magnitudes. Of the entire ~1250 sources, 4 clearly show periods of variability greater than 100 days, while the rest have periods shorter than ~51 days or no reliable periods. The majority of the sources show either rather irregular variability or short periods faster than 2 days. Most of the sources with reliable period determination between 2 and 51 days belong to the low-variability group, although a few belong to the medium-variability group. All the variable sources with periods longer than 35 days appear to be very red with B - V > 1.5 and V - I > 2.1 magnitudes. We classify candidates of 51 Cepheids, 17 semi-regular variables, 3 Mira types, 2 RV(B) Tauri stars, 26 eclipsing binary systems and 1 active galactic nucleus. The majority of long-term variables in our sample belong to either Mira or semi-regular types, indicating that long-term variability may be more prominent in post-main sequence phases of late-type stars. The depth of the eclipsing dips of the 26 candidates for eclipsing binaries is equivalent to ~0.61 as the average relative size of the two stars in the binary system. Our results illustrate the power of the KMTNet Supernova Program for future studies of variable objects.

• 전자공학회논문지
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• 제50권12호
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• pp.14-21
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• 2013

위성 운용 및 우주 탐사 미션에서 레인징은 우주 항행체의 위치 정보를 얻기 위한 가장 필수적인 기술이다. 최근에 우주 탐사 미션의 정교한 수행을 위하여 우주 개발국들 간의 상호 협력의 중요성이 증대되고 있다. 상호 협력을 위하여 우주 개발국간의 상호 호환성을 가지는 레인징 시스템이 요구된다. 이러한 이유로, CCSDS는 디지털 표준 레인징 시스템으로서 의사 잡음 레인징을 권고하고 있다. CCSDS 표준 레인징 시스템에서의 의사 잡음 시퀀스의 길이는 심우주 미션에 적합하며 지구 근접 미션에 적용하기는 매우 길다. 본 논문에서는 저궤도 위성, 중궤도 위성 그리고 정지궤도 위성과 같은 지구 근접 미션에 적합한 짧은 길이의 의사 잡음 레인징 시퀀스를 제안하고, CCSDS 표준 의사 잡음 레인징 시스템을 포함하는 다중임무 수행에 적합한 가변길이 의사 잡음 레인징 시스템을 제안한다.

• 한국조경학회지
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• 제29권3호
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• pp.29-37
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• 2001

The purpose of this study is to determine the suitable illuminance model of an urban neighborhood park. To this end, 1 dependent variable and 11 independent variables were set, and multiple regression analysis was applied to find correlation between variables and the model. The results of this study are as follows; 1) Among 11 independent variables abstracted to study suitable illuminance model of an urban neighborhood park, as a result of analysis on correlation between suitable illuminance of a dependent variable and activity space by using dummy variables, activity type and illuminance by spaces the suitable illuminance required for an urban neighborhood park was much influenced by activity type, and the fact that the activity was not limited to a specific space. 2) As a result of multiple regression analysis, independent variables influencing the suitable illuminance model of an urban neighborhood park were activity space, illuminance by spaces, seated activity, standing activity, and sporting activity. And, for relative contribution of independent variables to suitable illuminance, activity with sporting showed an importance 22 times higher than seated activity. When the central square(Sp_1) of activity spaces was set to reference category using dummy variables, it showed a contribution 52 times higher than sorting space(Sp_7) and the central square as the most important variable. 3) It was analyzed that suitable illuminance of an urban neighborhood part was most influenced by sporting activity but the relative contribution of a sporting space where activity with sporting occurs was least in view of the function of the space. Very high illuminance is required to accept high activity, and if illuminance at a certain space becomes too high, it may influence the illuminance of other spaces, and may consequently have a negative effect on the suitable illuminance of an urban neighborhood park. The results of this study were mainly for teenagers and young adults in their twenties, so further concrete studies which consider gender and a wider age range are needed in the future. Based on subsequent study, suitable illuminance by spaces shall be suggested.

• Journal of Astronomy and Space Sciences
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• 제40권1호
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• pp.19-27
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• 2023

We present the results of using small telescopes in the United Arab Emirates (UAE) for observing variable stars and asteroids. Two telescopes, namely, 5" apochromatic refractor and 14" Schmidt-Cassegrain, at Al-Khatim Observatory (M44) were used for the observations. The targets were the three variable stars RR GEM, AG LMi, and DL CMi and the asteroid 22 Kalliope. We found a good consistency between our light curves and published ones for the calibration targets, i.e., the asteroid 22 Kalliope and the variable star RR GEM. According to previous studies, AG LMi has two suggested periods, 16.3 hours and 32.62 hours. Our results clearly confirm the second one, with a period of 32.6175 hours. The star DL CMi has several suggested periods as per previous studies, such as 4.0173 days, 1.9606 days, and 2.0086 days. Our observations confirm the first one, with a period of 4.0159 days. These results demonstrate the effectiveness of using small telescopes for observing variable stars and asteroids. This work provides some recommendations on using small telescopes for such observations.

• 천문학회보
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• 제31권2호
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• pp.62.1-62.1
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• 2006

• 대한수학회보
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• 제59권6호
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• pp.1471-1493
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• 2022

The goal of this paper is to establish the boundedness of bilinear Calderón-Zygmund operator BT and its commutator [b₁, b₂, BT] which is generated by b₁, b₂ ∈ BMO(ℝⁿ) (or ${\dot{\Lambda}}_{\alpha}$(ℝⁿ)) and the BT on generalized variable exponent Morrey spaces 𝓛^p(·),𝜑(ℝⁿ). Under assumption that the functions 𝜑₁ and 𝜑₂ satisfy certain conditions, the authors proved that the BT is bounded from product of spaces 𝓛^{p₁(·),𝜑₁}(ℝⁿ)×𝓛^{p₂(·),𝜑₂}(ℝⁿ) into space 𝓛^p(·),𝜑(ℝⁿ). Furthermore, the boundedness of commutator [b₁, b₂, BT] on spaces L^p(·)(ℝⁿ) and on spaces 𝓛^p(·),𝜑(ℝⁿ) is also established.

• 천문학회보
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• 제44권1호
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• pp.85.3-85.3
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• 2019

Pulsating variable is a star whose luminosity changes through periodic pulsation. There are radiative and dynamical mechanisms hidden in periodic brightness changes, and the physical quantities related with the mechanisms are also expected to vary periodically. The purpose of this study is to investigate the periodic variations of the physical quantities of the ${\delta}$ Scuti type variable, V350 Peg by simultaneous photometry and spectroscopy. In this poster, we present preliminary results on apparent magnitude and radial velocity at the surface.

• 대한수학회보
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• 제61권2호
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• pp.489-509
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• 2024

In this paper, let q ∈ (0, 1]. We establish the boundedness of intrinsic g-functions from the Hardy-Lorentz spaces with variable exponent H^p(·),q(ℝⁿ) into Lorentz spaces with variable exponent L^p(·),q(ℝⁿ). Then, for any q ∈ (0, 1], via some estimates on a discrete Littlewood-Paley g-function and a Peetre-type maximal function, we obtain several equivalent characterizations of H^p(·),q(ℝⁿ) in terms of wavelets.

• 한국가구학회지
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• 제24권3호
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• pp.247-256
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• 2013

A dormitory is the most important compound space to college students who have to live with others. Also, for the students living in the boarding area, the dorm space can be the space for learning, exchanges and cultural. These Housing environment is a public space, so this is based on Universal Design. However, the 1970s-built dormitory space for the current user is narrow and not right for furniture standard. In this study, in order to compensate for these problems, the design directions are based on the previous studies - Park, Young-Soon, 2008, 'A Proposal on Dormitory Furniture Design for University Students.' Based on the previous study, the type of variable design is designed for desks, bookcases, beds, wardrobes, and other cabinets as representative household types. Furthermore, these furnitures are assembled and transformed depend on the dormitory space for single, double and four students. The furniture assembly system and arrangement module are presented in the direction of three kinds of designs. Therefore, three meaning of this study are the development of design to be used each item, the realization of custom furniture for space and presenting variable design module.