• 식물분류학회지
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• 제51권3호
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• pp.305-318
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• 2021

We report 14 species of flowering plants as new additions to the flora of Laos. These are Illex viridis (Aquifoliaceae), Capparis erycibe (Capparaceae), Euphorbia bokorensis (Euphorbiaceae), Exacum darae (Gentianaceae), Aeschynanthus cambodiensis (Gesneriaceae), Tetraphyllum roseum (Gesneriaceae), Utricularia gibba (Lentibulariaceae), Macrosolen brandisianus (Loranthaceae), Decaschistia siamensis (Malvaceae), Nyssa yunnanensis (Nyssaceae), Adenia penangiana var. penangiana (Passifloraceae), Pentaphylax euryoides (Pentaphylacaceae), Wikstroemia bokorensis (Thymelaeaceae), and Debregeasia wallichiana (Urticaceae). We discovered the species during a botanical survey of the Phou Khao Khouay National Biodiversity Conservation Area (PKKNBCA) of Lao PDR in 2015-2019. In addition, nine rarely collected flowering plant species in Laos are newly reported for the PKKNBCA.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제26권4호
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• pp.333-342
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• 2022

In this paper, we perform a direct comparison study of real experimental data for domain rearrangement and the Cahn-Hilliard (CH) equation on the dynamics of morphological evolution. To validate a mathematical model for physical phenomena, we take initial conditions from experimental images by using an image segmentation technique. The image segmentation algorithm is based on the Mumford-Shah functional and the Allen-Cahn (AC) equation. The segmented phase-field profile is similar to the solution of the CH equation, that is, it has hyperbolic tangent profile across interfacial transition region. We use unconditionally stable schemes to solve the governing equations. As a test problem, we take domain rearrangement of lipid bilayers. Numerical results demonstrate that comparison of the evolutions with experimental data is a good benchmark test for validating a mathematical model.

• Korean Circulation Journal
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• 제53권5호
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• pp.347-349
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• 2023

• 한국식품영양과학회지
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• 제33권8호
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• pp.1353-1358
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• 2004

국내산 충매 화분인 도토리 화분과 다래 화분에 단백질 분해효소를 이용하여 화분 추출물을 제조하고, 추출물의 조단백질 함량과 환원당 함량의 변화를 알아보았다. 도토리화분의 일반성분 분석결과 수분 5.2%, 회분 2.7%, 조지방 6.2%, 조단백질 함량은 22.3%였고, 다래화분은 수분 5.4%, 회분 2.8%, 조지방 1.8%, 조단백질 함량은 27.8%였다. Casein을 기질로 사용하여 측정한 효소의 비환성 (specific activity U/mg)은 Protease S>Flavozyme>Alcalase 2.4L>Protamex>Protease P>Protease A의 순이었다. 단백질 분해효소 처리에 의한 화분 추출물의 조단백질 함량은 효소 첨가군이 대조군보다 증가했고, Alcalase 2.4L을 0.2 U, 0.5 U 첨가시에 도토리 화분 추출물은 대조군보다 각각 35.8%, 45.8%, 다래 화분 추출물은 각각 68.8%, 101.5% 증가하였다. 단백질 분해효소 처리에 의한 화분 추출물의 환원당 함량은 효소 첨가군이 대조군보다 증가했고, Protease A를 0.2 U, 0.5 U 첨가 시 도토리 화분 추출물은 대조군보다 각각 11.4%, 18.4%, 다래 화분 추출물은 대조군보다 각각 12.2%, 14.2% 증가하였다. 단백질 분해 효소 처리에 의해 화분 추출물의 조단백질과 환원당의 함량이 증가되었고, 단백질 분해 효소는 화분 추출물의 조단백질 및 환원당 함량을 높이는 방법 중의 하나로 이용될 수 있다고 사료된다.

• 호남수학학술지
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• 제37권4호
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• pp.441-455
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• 2015

In this paper, we perform a comparison study of explicit and implicit numerical methods for the equity-linked securities (ELS). The option prices of the two-asset ELS are typically computed using an implicit finite diffrence method because an explicit finite diffrence scheme has a restriction for time steps. Nowadays, the three-asset ELS is getting popularity in the real world financial market. In practical applications of the finite diffrence methods in computational finance, we typically use relatively large space steps and small time steps. Therefore, we can use an accurate and effient explicit finite diffrence method because the implementation is simple and the computation is fast. The computational results demonstrate that if we use a large space step, then the explicit scheme is better than the implicit one. On the other hand, if the space step size is small, then the implicit scheme is more effient than the explicit one.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제22권2호
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• pp.159-168
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• 2015

Abstract. We propose a fast and robust finite difference method for Merton's jump diffusion model, which is a partial integro-differential equation. To speed up a computational time, we compute a matrix so that we can calculate the non-local integral term fast by a simple matrix-vector operation. Also, we use non-uniform grids to increase efficiency. We present numerical experiments such as evaluation of the option prices and Greeks to demonstrate a performance of the proposed numerical method. The computational results are in good agreements with the exact solutions of the jump-diffusion model.

• 대한수학회논문집
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• 제30권3호
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• pp.297-311
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• 2015

We present a robust and accurate boundary condition for pricing financial options that is a hybrid combination of the payoff-consistent extrapolation and the Dirichlet boundary conditions. The payoff-consistent extrapolation is an extrapolation which is based on the payoff profile. We apply the new hybrid boundary condition to the multi-dimensional Black-Scholes equations with a high correlation. Correlation terms in mixed derivatives make it more difficult to get stable numerical solutions. However, the proposed new boundary treatments guarantee the stability of the numerical solution with high correlation. To verify the excellence of the new boundary condition, we have several numerical tests such as higher dimensional problem and exotic option with nonlinear payoff. The numerical results demonstrate the robustness and accuracy of the proposed numerical scheme.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제20권2호
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• pp.163-174
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• 2016

In this paper, we propose an optimal choice scheme to determine the best option among comparable options whose current expectations are all the same under the condition that an investor has a confidence in the future value realization of underlying assets. For this purpose, we use a path-averaged option as our base instrument in which we calculate the time discounted value along the path and divide it by the number of time steps for a given expected path. First, we consider three European call options such as vanilla, cash-or-nothing, and asset-or-nothing as our comparable set of choice schemes. Next, we perform the experiments using historical data to prove the usefulness of our proposed scheme. The test suggests that the path-averaged option value is a good guideline to choose an optimal option.

• Current Optics and Photonics
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• 제1권1호
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• pp.7-11
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• 2017

In this study, multilayered graphene was easily transferred to the target substrate in one step using thermal release tape. The transmittance of the transferred graphene according to the number of layers was measured using a spectrophotometer. The sheet resistance was measured using a four-point probe system. Graphene formed using this transfer method showed almost the same electrical and optical properties as that formed using the conventional poly (methyl methacrylate) transfer method. This method is suitable for the mass production of graphene because of the short process time and easy large-area transfer. In addition, multilayered graphene can be transferred on various substrates without wetting problem using the one-step dry transfer method. In this work, this easy transfer method was used for dielectric substrates such as glass, paper and polyethylene terephthalate, and a sheet resistance of ~240 ohm/sq was obtained with three-layer graphene. By fabricating organic solar cells, we verified the feasibility of using this method for optoelectronic devices.

• 보건행정학회지
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• 제32권4호
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• pp.380-388
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• 2022

Background: Emerging infectious diseases, such as Middle East respiratory syndrome or coronavirus disease 2019, pose a continuous threat to public health, making a risk assessment necessary for infectious disease control and prevention. Therefore, we aimed to investigate the risk assessment methods for infectious diseases used by major foreign countries and organizations. Methods: We conducted an investigation and comparative analysis of risk assessment and risk determination methods for infectious diseases. The risk assessment tools included the strategic toolkit for assessing risks, influenza risk assessment tool, pandemic severity assessment framework, and rapid risk assessment methodology. Results: The most frequently reported risk elements were disease severity, antiviral treatment, attack rate, population immunity, and basic productive ratio. The risk evaluation method was evaluated quantitatively and qualitatively by the stakeholders at each institution. Additionally, the final risk level was visualized in a matrix, framework, and x and y-axis. Conclusion: Considering the risk assessment tools, the risk element was classified based on the duplicate of each indicator, and risk evaluation and level of risk assessment were analyzed.