• Journal of Wetlands Research
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• v.18 no.3
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• pp.250-261
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• 2016

The Philippines is a naturally water-rich archipelago capable of sustaining its ecological goods and providing services and needs of its people. Several waterbodies have been declared as natural wetlands in the country supporting the needs of community like water and food. In this study, 65 natural wetlands were considered including six sites that were identified as 'Wetlands of International Importance' such as Naujan Lake National Park, Agusan Marsh Wildlife Sanctuary, Olango Island Wildlife Sanctuary, Tubbataha Reefs Natural Park, Las $Pi{\tilde{n}}as-Para{\tilde{n}}aque$ Critical Habitat and Ecotourism Area and Puerto Princesa Subterranean River National Park. There are 22 wetland types presented in this research categorizing the Philippine wetlands. Philippine wetlands are now facing tremendous challenges such as land use conversion, abuse of resources, pollution coming from domestic, industrial and agricultural activities, and climate change. This paper provides an overview of Philippine wetlands in terms of their characteristics and components, impacts in the ecosystem, and the challenges they are dealing with. Moreover, the preservation measures that the government and private agencies implements to these wetlands were discussed and assessed. The enforcement of local and national laws concerning wetlands is found to be inadequate resulting in poor quality wetlands. The preservation and utilization of these wetlands can be maximized with a voluntary participation of whole Philippine community.

• Ocean and Polar Research
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• v.41 no.3
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• pp.121-133
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• 2019

Natural variability associated with a variety of large-scale climate modes causes regional differences in sea level rise (SLR), which is particularly remarkable in the Pacific Ocean. Because the superposition of the natural variability and the background anthropogenic trend in sea level can potentially threaten to inundate low-lying and heavily populated coastal regions, it is important to quantify sea level variability associated with internal climate variability and understand their interaction when projecting future SLR impacts. This study seeks to identify the dominant modes of sea level variability in the tropical Pacific and quantify how these modes contribute to regional sea level changes, particularly on the two strong El $Ni{\tilde{n}}o$ events that occurred in the winter of 1997/1998 and 2015/2016. To do so, an adaptive data analysis approach, Ensemble Empirical Mode Decomposition (EEMD), was undertaken with regard to two datasets of altimetry-based and in situ-based steric sea levels. Using this EEMD analysis, we identified distinct internal modes associated with El $Ni{\tilde{n}}o$-Southern Oscillation (ENSO) varying from 1.5 to 7 years and low-frequency variability with a period of ~12 years that were clearly distinct from the secular trend. The ENSO-scale frequencies strongly impact on an east-west dipole of sea levels across the tropical Pacific, while the low-frequency (i.e., decadal) mode is predominant in the North Pacific with a horseshoe shape connecting tropical and extratropical sea levels. Of particular interest is that the low-frequency mode resulted in different responses in regional SLR to ENSO events. The low-frequency mode contributed to a sharp increase (decrease) of sea level in the eastern (western) tropical Pacific in the 2015/2016 El $Ni{\tilde{n}}o$ but made a negative contribution to the sea level signals in the 1997/1998 El $Ni{\tilde{n}}o$. This indicates that the SLR signals of the ENSO can be amplified or depressed at times of transition in the low-frequency mode in the tropical Pacific.

• Bulletin of the Korean Mathematical Society
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• v.35 no.3
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• pp.432-439
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• 1998

The main purpose of this paper is to give a characterization of a totally geodesic Kaehler submanifold M of a Kaehler manifold $\tilde{M}$ by observing the extrinsic shape of particular circles of the submanifold M.

• Honam Mathematical Journal
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• v.35 no.3
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• pp.329-342
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• 2013

We study lightlike hypersurfaces M of a semi-Riemannian space form $\tilde{M}(c)$ with a semi-symmetric non-metric connection whose structure vector field is tangent to M. Our main result is two characterization theorems for such a lightlike hypersurface.

• Journal for History of Mathematics
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• v.14 no.1
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• pp.115-123
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• 2001

In this paper we consider the topological properties of $\textit{\Theta}_\textit{\kappa}$and show that the induced map $\tilde{\textit{\Theta}_\textit{\kappa}}$ is well defined and renders the diagram commutative.

• Korean Journal of Mathematics
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• v.31 no.2
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• pp.133-137
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• 2023

Consider a Riemannian manifold M equipped with a metric g. In this article, we study a notion for statistical manifolds (M, g, ∇), which can have a nonzero torsion, abbreviated to SMT. Then it turns out that the tensor fields ∇g and ${\tilde{\nabla}}g$ obtained from two different SMT-connections are different.

• Speech Sciences
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• v.9 no.3
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• pp.133-140
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• 2002

The purpose of this study was to investigate any changes in acoustic qualities of voice as ,a function of nasalance, in order to determine the relationship between vocal quality and nasalance. Twenty normal subjects (10 males and 10 females) vocalized /a/, /$\tilde{a}$/, and /a $\eta$/. The changes in nasalance and acoustic characteristics of the voice were analyzed by Nasometer (Model 6200-3, Kay Elemetrics, co) and Dr, Speech 4.0 (Tiger Electronics, Co), respectively. One-way ANOVA was used to examine any changes in jitter, shimmer, harmonics-to-noise ratio, and normalized noise energy relative to the nasalance in 3 types of vocalization. The Person r correlation coefficient was used to identify the relationship between the nasalance and the vocal quality. There was no statistically significant changes in jitter, shimmer, HNR and NNE. The jitter, however, tended to increase as the nasalance socre increased, compared to the other vocal parameters. In addition, the NNE showed an increase on / $\tilde{a}$/, and /a $\eta$/, more on the /a $\eta$/. Thus, it was speculated that NNE could be used to identify or screen resonant disorders with hypernasality

• Journal of the Korean Society of Combustion
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• v.10 no.3
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• pp.25-33
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• 2005

Fast-time instability is investigated for diffusion flames with Lewis numbers greater than unity by employing the numerical technique called the Evans function method. Since the time and length scales are those of the inner reactive-diffusive layer, the problem is equivalent to the instability problem for the $Li\tilde{n}\acute{a}n#s$ diffusion flame regime. The instability is primarily oscillatory, as seen from complex solution branches and can emerge prior to reaching the upper turning point of the S-curve, known as the $Li\tilde{n}\acute{a}n#s$ extinction condition. Depending on the Lewis number, the instability characteristics is found to be somewhat different. Below the critical Lewis number, $L_C$, the instability possesses primarily a pulsating nature in that the two real solution branches, existing for small wave numbers, merges at a finite wave number, at which a pair of complex conjugate solution branches bifurcate. For Lewis numbers greater than $L_C$, the solution branch for small reactant leakage is found to be purely complex with the maximum growth rate found at a finite wave number, thereby exhibiting a traveling nature. As the reactant leakage parameter is further increased, the instability characteristics turns into a pulsating type, similar to that for L < $L_C$.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.150-151
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• 2011

최근 25년간(1986-2010년)의 우리나라 기상청 및 일본 기상청 자료를 사용하여 엘니뇨 라니냐 현상과 태풍과의 관계를 분석하였다. 특히, 이번 연구에서는 태풍의 세기에 주목하여 분석하였다. 주요 연구 결과는 다음과 같다. 태풍의 세기를 나타내는 평균 중심최저기압과 평균 최대풍속은 엘니뇨 발생년에 959.3hPa과 35.8m/s, 라니냐 발생년에 965.5hPa과 33.7m/s 그리고 25년 전 기간에 대하여는 962.3hPa과 35.0m/s이었다. 즉, 엘니뇨 발생년의 태풍의 세기가 라니냐 발생년의 태풍의 세기보다 강함을 알 수 있다. 구체적으로 평균 중심최저기압은 약 6hPa 낮고, 평균 최대풍속은 2.1m/s 강하다. 이와 같은 결과는 태풍의 발생 해역과 밀접히 관련되어 있다. 즉, 엘니뇨 발생년에 태풍은 동경 150도 이동 해역과 북위 10도 이남 해역에서 상대적으로 더 많이 발생하고, 라니냐 발생년의 태풍은 동경 150도 이서 해역과 북위 20도 이북 해역에서 더 많이 발생한다. 동경 150도 이동 해역과 북위 10도 이남 해역에서 발생한 태풍은 북태평양의 광범위한 고수온역을 보다 장시간 이동하게 되므로 더 강하게 발달할 수 있다.

• Bulletin of the Korean Mathematical Society
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• v.57 no.3
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• pp.649-660
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• 2020

This paper proves a new regularity criterion for solutions to the Cauchy problem of the 3D Boussinesq equations via one directional derivative of the horizontal component of the velocity field (i.e., (∂_iu₁; ∂_ju₂; 0) where i, j ∈ {1, 2, 3}) in the framework of the anisotropic Lebesgue spaces. More precisely, for 0 < T < ∞, if $$\large{\normalsize\displaystyle\smashmargin{2}{\int\nolimits_o}^T}({\HUGE\left\|{\small{\parallel}{\partial}_iu_1(t){\parallel}_{L^{\alpha}_{x_i}}}\right\|}{\small^{\gamma}_{L^{\beta}_{x_{\hat{i}}x_{\bar{i}}}}+}{\HUGE\left\|{\small{\parallel}{\partial}_iu_2(t){\parallel}_{L^{\alpha}_{x_j}}}\right\|}{\small^{\gamma}_{L^{\beta}_{x_{\hat{i}}x_{\bar{i}}}}})dt<{{\infty}},$$ where ${\frac{2}{{\gamma}}}+{\frac{1}{{\alpha}}}+{\frac{2}{{\beta}}}=m{\in}[1,{\frac{3}{2}})$ and ${\frac{3}{m}}{\leq}{\alpha}{\leq}{\beta}<{\frac{1}{m-1}}$, then the corresponding solution (u, θ) to the 3D Boussinesq equations is regular on [0, T]. Here, (i, ${\hat{i}}$, ${\tilde{i}}$) and (j, ${\hat{j}}$, ${\tilde{j}}$) belong to the permutation group on the set 𝕊₃ := {1, 2, 3}. This result reveals that the horizontal component of the velocity field plays a dominant role in regularity theory of the Boussinesq equations.