• Current Photovoltaic Research
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• v.11 no.2
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• pp.39-43
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• 2023

Carrier-selective contacts (CSCs) solar cells are considerably attractive on highly efficient crystalline silicon heterojunction (SHJ) solar cells due to their advantages of high thermal tolerance and the simple fabrication process. CSCs solar cells require a hole selective contact (HSC) layer that selectively collects only holes. In order to selectively collect holes, it must have a work function characteristic of 5.0 eV or more when contacted with n-type Si. The VO_x, NiO_x, and CuI_x thin films were fabricated and analyzed respectively to confirm their potential usage as a hole-selective contact (HSC) layer. All thin films showed characteristics of band-gap engergy > 3.0 eV, work function > 5.0 eV and minority carrier lifetime > 1.5 ms.

• Journal of the Korean Mathematical Society
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• v.60 no.3
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• pp.565-586
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• 2023

We study the Dirichlet problem for the degenerate nonlocal parabolic equation u_t - a(||∇u||²_L²(Ω))∆u = C_b ||u||^β_L²(Ω) |u|^q(x,t)-2 u log |u| + f in Q_T, where Q_T := Ω × (0, T), T > 0, Ω ⊂ ℝ^N, N ≥ 2, is a bounded domain with a sufficiently smooth boundary, q(x, t) is a measurable function in Q_T with values in an interval [q^-, q⁺] ⊂ (1, ∞) and the diffusion coefficient a(·) is a continuous function defined on ℝ₊. It is assumed that a(s) → 0 or a(s) → ∞ as s → 0⁺, therefore the equation degenerates or becomes singular as ||∇u(t)||2 → 0. For both cases, we show that under appropriate conditions on a, β, q, f the problem has a global in time strong solution which possesses the following global regularity property: ∆u ∈ L²(Q_T) and a(||∇u||²_L²(Ω))∆u ∈ L²(Q_T ).

• Communications of the Korean Mathematical Society
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• v.38 no.4
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• pp.1141-1151
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• 2023

Let C_a,b[0, T] denote the space of continuous sample paths of a generalized Brownian motion process (GBMP). In this paper, we study the structures which exist between the analytic generalized Fourier-Feynman transform (GFFT) and the generalized convolution product (GCP) for functions on the function space C_a,b[0, T]. For our purpose, we use the exponential type functions on the general Wiener space C_a,b[0, T]. The class of all exponential type functions is a fundamental set in L₂(C_a,b[0, T]).

• Communications of the Korean Mathematical Society
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• v.22 no.3
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• pp.365-367
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• 2007

In this paper we explicitly compute the p-adic order of $log_p(1-\zeta_{p^n})$.

• Structural Engineering and Mechanics
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• v.28 no.4
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• pp.373-386
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• 2008

In this study stochastic analysis of non-linear dynamical systems under ${\alpha}$-stable, multiplicative white noise has been conducted. The analysis has dealt with a special class of ${\alpha}$-stable stochastic processes namely sub-Gaussian white noises. In this setting the governing equation either of the probability density function or of the characteristic function of the dynamical response may be obtained considering the dynamical system forced by a Gaussian white noise with an uncertain factor with ${\alpha}/2$- stable distribution. This consideration yields the probability density function or the characteristic function of the response by means of a simple integral involving the probability density function of the system under Gaussian white noise and the probability density function of the ${\alpha}/2$-stable random parameter. Some numerical applications have been reported assessing the reliability of the proposed formulation. Moreover a proper way to perform digital simulation of the sub-Gaussian ${\alpha}$-stable random process preventing dynamical systems from numerical overflows has been reported and discussed in detail.

• Geomechanics and Engineering
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• v.34 no.1
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• pp.51-67
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• 2023

In this research, the degradation rate of physical properties of the Angouran pit bedrock (calc-schist) is first investigated under the specific numbers of freeze-thaw (F-T) cycles. Then, the durability of calc-schist specimens against the F-T cycle number (N) is examined considering the mechanical parameters, and using the decay function and half-time techniques. For this purpose, point load strength (I_S(50)), second durability index (I_d2), Brazilian tensile strength (BTS), and compressive (V_P) and shear (V_S) wave velocities of calc-schist specimens are measured after 0, 7, 15, 40, and 75 N. For comparing the degradation rate of mechanical properties of available rock types on the Angouran mine walls, these tests are also carried out on the limestone and amphibolite schist specimens beside the calc-schist. According to test results, the exponential regression models are developed between the mechanical parameters of rock specimen's and N variable. Also, the long-term durability of each rock type versus N is studied using the decay function and half-time techniques. Results indicated that the degradation rate differs for the above rock types in which amphibolite schist and calc-schist specimens have the highest and least resistance against the N, respectively. The obtained results from this study can play a key role in the optimal design of the mine's final walls.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.652-658
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• 1998

We introduce the concept of a bi-population scheme for real-coded GAs consisting of an explorer sub-Ga and an exploiter sub-GA. The explorer sub-GA mainly performs global exploration of the search space, and incorporates a restart mechanism to help avoid being trapped at local optima. The exploiter sub-GA performs exploitation of fit local areas of the search space around the neighborhood of the best-so-far solution. Thus the search function of the algorithm is divided. the proposed technique exhibits performance significantly superior to standard GAs on two complex highly multimodal problems.

• Tuberculosis and Respiratory Diseases
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• v.85 no.2
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• pp.175-184
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• 2022

Background: Post-tuberculosis (TB) sequelae is a commonly encountered clinical entity, especially in high TB burden countries. This may represent chronic anatomic sequelae of previously treated TB, with frequent symptomatic presentation. This pilot study was aimed to investigate the pulmonary functions and systemic inflammatory markers in patients with post-TB sequelae (PTBS) and to compare them with post-TB without sequelae (PTBWS) participants and healthy controls. Methods: A total of 30 participants were enrolled, PTBS (n=10), PTBWS (n=10), and healthy controls (n=10). Pulmonary function tests included spirometry and measurement of airway impedance by impulse oscillometry. Serum levels of matrix metalloproteinase (MMP)-1, transforming growth factor-β, and interferon-γ were estimated. Results: Slow vital capacity (SVC), forced vital capacity (FVC), forced expiratory volume in 1 second (FEV₁), FEV₁/FVC, and peak expiratory flow were significantly lower in PTBS as compared to controls. SVC and FEV₁ were significantly less in PTBS as compared to PTBWS. Total airway impedance (Z₅), total airway resistance (R₅), central airway resistance (R₂₀), area of reactance (Ax), and resonant frequency (Fres) were significantly higher and respiratory reactance at 5 and 20 Hz (X₅, X₂₀) were significantly lower in PTBS as compared to PTBWS. Spirometry parameters correlated with impulse oscillometry parameters in PTBS. Serum MMP-1 level was significantly higher in PTBS as compared to other groups. Conclusion: Significant pulmonary function impairment was observed in PTBS, and raised serum MMP-1 levels compared with PTBWS and healthy controls. Follow-up pulmonary function testing is recommended after treatment of TB for early diagnosis and treatment of PTBS.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.4
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• pp.1-17
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• 2023

PURPOSE: The purpose of this study was to compare how the shoulder height and respiratory function are affected by applying shoulder stabilization exercises and core stabilization exercises that are effective for strengthening the trunk muscles and postural stability for adults with a round shoulder posture (RSP). METHODS: The participants were 28 young adults with RSP. They were assigned randomly to two groups: shoulder stabilization exercise and core stabilization exercise. They performed the exercises for 30 minutes twice a week for four weeks. They measured the shoulder height and respiratory function before and after exercise. RESULTS: No significant difference in shoulder height was found between the groups. A significant decrease in shoulder height was found in the shoulder stabilization exercise group after exercise. The core stabilization exercise group showed a significant decrease after exercise. In respiratory function, no significant difference was found between the groups. The forced vital capacity (FVC) and forced expiratory volume in one second (FEV₁) were increased significantly in the shoulder stabilization exercise group before and after exercise. The FEV₁, FEV₁/FVC, and peak expiratory flow were significantly higher in the shoulder stabilization exercise group after exercise than in the core stabilization exercise group. CONCLUSION: Shoulder stabilization exercise and core stabilization exercise improved the postural alignment and pulmonary function, and the exercises could be helpful in shoulder rehabilitation as well as the clinical part of the treatment of rounded shoulder posture.

• Journal of the Chungcheong Mathematical Society
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• v.15 no.2
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• pp.41-46
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• 2003

In this paper, we investigate the $SP_{\alpha}$-integral and the $M_{\alpha}$-integral defined on an interval of the n-dimensional Euclidean space $\mathbb{R}^n$. In particular, we show that these two integrals are equivalent.