• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1876-1881
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• 2003

When a projectile travels at high speed underwater, supercavitating flow arises, in which a huge cavity is generated behind the projectile so that only the nose, i.e., the cavitator, of the projectile is wetted, while the rest of it should be surrounded by the cavity. In that case, the projectile can achieve very high speed due to the reduced drag. Furthermore if the nose of the body is shaped properly, the attendant pressure drag can be maintained at a very low value, so that the overall drag is also reduced dramatically. In this study, shape optimization technique is employed to determine the optimum cavitator shape for minimum drag, given certain operating conditions. Shape optimization technique is also used to solve the potential flow problem for any given cavitator, which is a free boundary value problem having the cavity shape as unknown a priori. Analytical sensitivities are derived for various shape parameters in order to implement a gradient-based optimization algorithm. Simultaneous optimization technique is proposed for efficient cavitator shape optimization, in which the cavity and cavitator shape are determined in a single optimization routine.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1163-1168
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• 2006

Manufacturing technology for the production of high value-added fine chemical products is emphasized and getting more attention as the diversified interests of customers and the demand of high quality products are getting bigger and bigger everyday. Thus, the development of advanced batch processes, which is the preferred and most appropriate way of producing these types of products, and the related technologies are becoming more important. Therefore, high-precision batch distillation is one of the important elements in the successful manufacturing of fine chemicals, and the importance of the process operation strategy with quality assurance cannot be overemphasized. Accordingly, proposing a process structure explanation and operation strategy of such processes including batch processes and batch distillation would be of great value. We investigate optimal operation strategy and production planning of multi-purpose plants consisting of batch processes and batch distillation for the manufacturing of fine chemical products. For the short-term scheduling of a sequential multi-purpose batch plant consisting of batch distillation under MPC and UIS policy, we proposed a MILP model based on a priori time slot allocation. Also, we consider that the waste product of being produced on batch distillation is recycled to the batch distillation unit for the saving of raw materials. The developed methodology will be especially useful for the design and optimal operations of multi-purpose and multiproduct plants that is suitable for fine chemical production.

• Journal of the Korean Society of Earth Science Education
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• v.17 no.2
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• pp.102-122
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• 2024

The aim of the study is to explore how to approach the inherent value of nature, which is the main object of earth science education, beyond its instrumental value, which is its external usefulness. Above all, it is said to be an activity-based inherent value in the entire transfer process of the experiment, which includes psychological elements. At the core of environmental ethics is value and the utilitarian question of what is worth continuing. It is a matter of more than simply continuation. The answer is the sustainable value of the natural environment, an education that must preserve its beauty as an inherent value, that is, as a heritage value as a lover of life. Furthermore, the area of valuation must be upgraded from synchronic to diachronic ethical values, with sustainable values instead of intrinsic values. In environmental ethics, the intrinsic value that shows the beauty of knowledge itself is called bequest value. The study distinguished between a priori intrinsic value that ignores existing experience and intrinsic value that is experience-oriented and activity-oriented. In addition, the intrinsic value principle centered on activities was explored through scientific experiments in earth science education and Eratosthenes's earth size measurement experiment. The value principle according to the scientific worldview serves as the basis for value judgment. Above all, intrinsic value was being revealed through the active value experience of the experiment, in which aesthetic values were involved in the process of inferring the experiment results. As an educational implication, it should be value-education that helps us internally transfer intrinsic values rather than instrumental values, which are the basis for creating a sustainable society and nature.

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.153-167
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• 2020

Purpose - The purpose of this study is to examine whether social value-related expenditures can be recognized as intangible assets in financial statements. Design/methodology/approach - This study examined social values defined in the economic and management fields and analyzed whether the social values have the characteristics of intangible assets. For this, the general definition of social value was derived from the concept of social value covered in previous studies. Next, we reviewed the definitions and recognition requirements for intangible assets under the current accounting standards. Based on this, we tried to suggest new criteria and disclosure methods for reporting social value-related expenditures that are not currently reported in financial statements as intangible assets in the financial statements and notes. Findings - First, as a criterion for recognizing social value-related expenditure as an intangible asset, we propose a relationship between social value-related expenditure and enterprise value. Where social value-related expenditures have a statistically significant positive impact on corporate value, they are recognized as intangible assets. If social value-related expenditures have a statistically significant negative influence on business value, or the impact of social value-related expenditures on the enterprise value is not statistically significant, it is not recognized as asset. Second, new disclosure plans are proposed according to the combination of intangible assets by category and the relevance of enterprise value. After dividing social value-related expenditures into separate intangible asset categories, if social value-related expenditures have a statistically significant positive impact on corporate value, they are recognized as intangible assets in the financial statements. If expenditures have a statistically significant negative impact on business value, they should be recorded as essential notes. Finally, if the impact of social value-related expenditure on corporate value is not statistically significant, it should be listed as a supplement. Research implications or Originality - This study contributes to the concurrent research in that it is a priori study on whether social value-related expenditure can be recognized as an asset. This study suggests that the economic effect of social expenditure can be recognized in corporate financial statements, thereby providing companies with justification and effectiveness of social value-related expenditure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8A
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• pp.671-678
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• 2005

This paper proposed symbol rate method which does not require a priori knowledge on the symbol rate and simplified modulation identification method to classify BPSK, QPSK, 8PSK signal. In order to estimate the unknown symbol rate, sliding FFT and simple moving average to estimate the spectrum of the signals is utilized, and sliding window and decimation, LPF blcok to estimate the proper symbol rate is used. Although conventional modulation ID method must use SNR value as the test statistics, the receiver cannot estimate the SNR value since the receiver cannot know the modulation type at the start of communication, and bit resolution is high due to using nonlinear function such as log, cosh. Therefore, we proposed the simplified fixed SNR value method. The performance of symbol rate estimation and modulation ID is shown using Monte Carlo computer simulation. This paper show that symbol rate estimation also has good performance in low SNR, and proposed simplified fixed SNR method has almost equivalent performance compared to conventional method.

• Bulletin of the Korean Mathematical Society
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• v.57 no.4
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• pp.1003-1031
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• 2020

We consider the following Dirichlet initial boundary value problem with a gradient absorption and a nonlocal source $$\frac{{\partial}u}{{\partial}t}-div({\mid}{\nabla}u{\mid}^{p-2}{\nabla}u)={\lambda}u^k{\displaystyle\smashmargin{2}{\int\nolimits_{\Omega}}}u^sdx-{\mu}u^l{\mid}{\nabla}u{\mid}^q$$ in a bounded domain Ω ⊂ ℝ^N, where p > 1, the parameters k, s, l, q, λ > 0 and µ ≥ 0. Firstly, we establish local existence for weak solutions; the aim of this part is to prove a crucial priori estimate on |∇u|. Then, we give appropriate conditions in order to have existence and uniqueness or nonexistence of a global solution in time. Finally, depending on the choices of the initial data, ranges of the coefficients and exponents and measure of the domain, we show that the non-negative global weak solution, when it exists, must extinct after a finite time.

• Structural Engineering and Mechanics
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• v.21 no.5
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• pp.539-551
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• 2005

Finite elements based on isoparametric formulation are known to suffer spurious stiffness properties and corresponding stress oscillations, even when care is taken to ensure that completeness and continuity requirements are enforced. This occurs frequently when the physics of the problem requires multiple strain components to be defined. This kind of error, commonly known as locking, can be circumvented by using reduced integration techniques to evaluate the element stiffness matrices instead of the full integration that is mathematically prescribed. However, the reduced integration technique itself can have a further drawback - rank deficiency, which physically implies that spurious energy modes (e.g., hourglass modes) are introduced because of reduced integration. Such instability in an existing stiffness matrix is generally detected by means of an eigenvalue test. In this paper we show that a knowledge of the dimension of the solution space spanned by the column vectors of the strain-displacement matrix can be used to identify the instabilities arising in an element due to reduced/selective integration techniques a priori, without having to complete the element stiffness matrix formulation and then test for zero eigenvalues.

• Journal of Korean Public Health Nursing
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• v.17 no.1
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• pp.113-121
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• 2003

Purpose : This study was performed to develop a scale of outdoor school safety behavior in Korean elementary students. Methods : A list of 40 items were selected by priori experiences of school health teachers and a literature review. For evaluation of the appropriateness of the 32 items, questionnaires were reviewed by an expert group which was consisted of 10 professionals. Validity of the 31 items was screened in this process with 4 point Likert scale. Using the preliminary tool. data were collected from 684 subjects for item analysis and factor analysis. A total of 26 items were remained, and items with the lower than 0.2 item-total correlation coefficient were removed. Factor analysis was done with these 26 items, and 26 items with factor loadings higher or equal to 0.4 were remained. Relsult : 1. Cronbach's alpha for the 26 items was 0.70 2. Five factors were identified with eigen value 1.0 These contributed $51.617\%$ of the variance in the total score. 3. Each factor was labled 'vonobserbance of safety rule', 'good habit for safety', 'careless action', 'lack of safety knowledge', 'injurious action to friend' It is suggested that this scale could be used to measure outdoor school safety behaviors among elementary students in Korea.

• Journal of Korea Multimedia Society
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• v.18 no.7
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• pp.886-894
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• 2015

In this paper, we conduct sensitivity analysis of parameters used for inverse modeling in order to estimate the PM₁₀ emissions from the 16 areas in East Asia accurately. Parameters used in sensitivity analysis are R, the observational error covariance matrix, and B, a priori (background) error covariance matrix. In previous studies, it was used with the predetermined parameter empirically. Such a method, however, has difficulties in estimating an accurate emissions. Therefore, an automatically determining method for the most suitable value of R and B with an error measurement criteria and posteriori emissions accuracy is required. We determined the parameters through a sensitivity analysis, and improved the accuracy of posteriori emissions estimation. Inverse modeling methods used in the emissions estimation are pseudo inverse, NNLS (Nonnegative Least Square), and BA(Bayesian Approach). Pseudo inverse has a small error, but has negative values of emissions. In order to resolve the problem, NNLS is used. It has a unrealistic emissions, too. The problems are resolved with BA(Bayesian Approach). We showed the effectiveness and the accuracy of three methods through case studies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.2
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• pp.207-217
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• 1993

In this paper, knowing a priori probability of phase offset between transmitted codes and reference codes in the receiver, we construct the state diagram of acquisition process of the direct sequence spread-spectrum communication system using the expanding window search. The scannings are performed from the cell with higher probability code epoch synchronization to that with lower one. We expand window size from initial value by r times of its previous size in each search, construct the corresponding the state diagrams, and derive average synchronization time using the Markov process and Mason's gain formula. Average synchronization times versus number of search n and detection probability $P_d$ are calculated.