• Journal of the Korean Solar Energy Society
• /
• v.29 no.2
• /
• pp.39-46
• /
• 2009

Heliostat, as a mirror system tracking the sun's movement, is the most important subsystem determining the efficiency of solar thermal power plant. Thus the accurate sun tracking performance under the various hazardous operating condition, is required. This study presents a methodology of development of the solar ray tracing technique and the application of it in the analysis of sun tracking error due to the heliostat geometrical errors. The geometrical errors considered here are the azimuth axis tilting error and the elevation axis tilting error. We first analyze the geometry of solar ray reflected from the heliostat. Then the point on the receiver, where the solar ray reflected from the heliostat is landed, is computed and compared with the original intended point, which represents the sun tracking error. The result obtained shows that the effect of geometrical error on the sun tracking performance is varying with time(season) and the heliostat location. It also shows that the heliostat located near the solar tower has larger sun tracking error than that of the heliostat located farther.

• Proceedings of the KSRS Conference
• /
• v.1
• /
• pp.79-81
• /
• 2006

Geostationary ocean satellite, unlike other sun-synchronous polar-orbit satellites, will be able to take a picture of a large region several times a day (almost with every one hour interval). For geostationary satellite, the target region is fixed though the location of sun is changed always. Thus, the ocean signal of a given target point is largely dependent on time. In other words, the ocean signal detected by geostationary satellite sensor must translate to the signal of target when both sun and satellite are located in nadir, using another correction model. This correction is performed with a standardization of signal throughout relative geometric relationship among satellite - sun - target points. One signal value of a selected pixel point of the target region of Geostationary Ocean Colour Imager (GOCI) would be set up as a standard, and the ratio of all remained pixel point can be calculated. This relative ratio called bidirectional factor, the result of modelling of spatiotemporal variation of bidirectional factor is shown.

• Bulletin of the Korean Mathematical Society
• /
• v.34 no.4
• /
• pp.525-533
• /
• 1997

We analysis spectral subspaces of $C^*$-algebras for a compacr group action. And we prove the condition that the fixed point algebra of the product action is the tensor product of the fixed point algebras.

• Honam Mathematical Journal
• /
• v.41 no.3
• /
• pp.609-617
• /
• 2019

We characterize two-point homogeneous spaces M by means of the structural operator $h={\frac{1}{2}}{\mathcal{L}}_{\xi}{\phi}$ or the characteristic Jacobi operator ${\ell}=R({\cdot},{\xi}){\xi}$ on the unit tangent sphere bundles $T_1M$.

• East Asian mathematical journal
• /
• v.24 no.1
• /
• pp.7-10
• /
• 2008

We prove a localization theorem of Azukawa pseudometric at a local plurisubharmonic peak point of a domain in the complex Euclidean space.

• Korean Journal of Mathematics
• /
• v.11 no.1
• /
• pp.71-77
• /
• 2003

In this paper we are going to study the dynamics of counting on the set S of functions from a finite subset of $\mathbb{N}=\{1,2,{\cdots}\}$ into $\mathbb{N}$. We have shown that every point $f{\in}S$ is either an eventually fixed point or an eventually periodic point of period 2 or 3.

• Kyungpook Mathematical Journal
• /
• v.63 no.1
• /
• pp.61-78
• /
• 2023

In this paper, we introduce two new geometric constants related to the heights of triangles: ∆_H(X) and ∆_h(X, I). We also propose two new geometric constants, ∆_m(X) and ∆_M(X), related to the midlines of equilateral triangles, and discuss the relation between the heights and midlines in equilateral triangles. We give estimates for these geometric constants in terms of other geometric parameters, and the geometric constants are used to discuss geometric properties such as uniform non-squareness, uniform normal structure, and the fixed point property.

• Bulletin of the Korean Mathematical Society
• /
• v.52 no.2
• /
• pp.685-697
• /
• 2015

We investigate the stability of nonlinear differential equations of the form $y^{(n)}(x)=F(x,y(x),y^{\prime}(x),{\cdots},y^{(n-1)}(x))$ with a Lipschitz condition by using a fixed point method. Moreover, a Hyers-Ulam constant of this differential equation is obtained.

• Korean Journal of Mathematics
• /
• v.30 no.4
• /
• pp.571-592
• /
• 2022

By established a Banach space with the Hausdorff distance, we introduce the alternative fixed-point theorem to explore the existence and uniqueness of a fixed subset of Y and investigate the stability of set-valued Euler-Lagrange functional equations in this space. Some properties of the Hausdorff distance are furthermore explored by a short and simple way.

• Korean Journal of Acupuncture
• /
• v.29 no.1
• /
• pp.23-36
• /
• 2012

Objectives : This study was conducted to investigate effective treatment point selection method using oppressive pain in acupoints as elementary attempt for standard methodology of clinical acupuncture studies. Methods : Twenty seven subjects with hypertension or within prehypertension category - systolic and diastolic blood pressure (BP) over 120/80mmHg - were divided into two groups, oppressive pain point treatment group and oppressive painless point treatment group. In oppressive pain point treatment group, single point acupuncture (SPA) was conducted for 16 sessions during 8 weeks on most oppressive painful point among 6 selected acupuncture points used in previous trials and clinic. As a SPA intervention, 15 minutes with deqi sensation- elevating manipulation was conducted on the treatment acupoint. Same process was conducted in oppressive painless point treatment group on most oppressive painless point with subject blinding. Results : Significant reduction was observed in both systolic and diastolic BP after short time intervention (15.5/8.8 mmHg, 10.7/7.1 mmHg, P<0.05, respectively at 1 week) and maintained for 8 weeks intervention period in all groups (12.8/8.0 mmHg, 19.4/12.6 mmHg, P<0.05, respectively). No significant difference of BP change between oppressive pain point treatment group (N=10) and oppressive painless point treatment group (N=9) was observed during 8 weeks study period. Conclusions : SPA treatment as used in this pilot study was effective for lowering BP in mild hypertensive population, but oppressive pain in acupoint had no effect on treatment. This present result suggests the possibility of SPA for hypertension treatment regardless of oppressive pain.