• Nonlinear Functional Analysis and Applications
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• 제27권3호
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• pp.449-469
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• 2022

This paper deals with the new iterative algorithm for approximating the fixed point of generalized 𝛼-nonexpansive mappings in a hyperbolic space. We show that the proposed iterative algorithm is faster than all of Picard, Mann, Ishikawa, Noor, Agarwal, Abbas, Thakur and Piri iteration processes for contractive mappings in a Banach space. We also establish some weak and strong convergence theorems for generalized 𝛼-nonexpansive mappings in hyperbolic space. The examples and numerical results are provided in this paper for supporting our main results.

• 한국환경과학회지
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• 제1권2호
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• pp.119-124
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• 1992

Cloud streets were successfully simulated by numerical model (RAMS) including an Isolated mountain near the coast, large sensible heat flux from the sea surface, uniform stratification and wind velocity with low Froude number (0.25) in the inflow boundary The well developed cloud streets between a pair of convective rolls are simulated at a level of 1 km over the sea. The following five results were obtained: 1) port the formation of the pair of convective rolls, both strong static instability and a topographically induced mechanical disturbance are strongly required at the same time. 2) Strong sensible heat flux from the sea surface is the main energy source of the pair of convective rolls, and the buoyancy caused by condensation in the cloud is negligibly small. 3) The pair o( convective rolls is a complex of two sub-rolls. One is the outer roll, which has a large radius, but weak circulation, and the other is the inner roll, which has a small radius, but strong circulation. The outer roll gathers a large amount of moisture by convergence in the lower marine boundary, and the inner roll transfers the convergent moisture to the upper boundary layer by strong upward motion between them. 4) The pair of inner rolls form the line-shaped cloud streets, and keep them narrow along the center-line of the domain. 5) Both by non-hydrostatic and by hydrostatic assumptions, cloud streets can be simulated. In our case, non-hydrostatic processes enhanced somewhat the formation of cloud streets. The horizontal size of the topography does not seem to be restricted to within the small scale where non-hydrostatic effects are important.

• Geomechanics and Engineering
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• 제18권2호
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• pp.215-224
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• 2019

Excavation of long tunnels by shielded TBMs is a safe, fast, and efficient method of tunneling that mitigates many risks related to ground conditions. However, long-distance tunneling in great depth through adverse geological conditions brings about limitations in the application of TBMs. Among various harsh geological conditions, squeezing ground as a consequence of tunnel wall and face convergence could lead to cluttered blocking, shield jamming and in some cases failure in the support system. These issues or a combination of them could seriously hinder the performance of TBMs. The technique of excavation has a strong influence on the tunnel response when it is excavated under squeezing conditions. The Golab water conveyance tunnel was excavated by a double-shield TBM. This tunnel passes mainly through metamorphic weak rocks with up to 650 m overburden. These metamorphic rocks (Shales, Slates, Phyllites and Schists) together with some fault zones are incapable of sustaining high tangential stresses. Prediction of the convergence, estimation of the creeping effects and presenting strategies to overcome the squeezing ground are regarded as challenging tasks for the tunneling engineer. In this paper, the squeezing potential of the rock mass is investigated in specific regions by dint of numerical and analytical methods. Subsequently, several operational solutions which were conducted to counteract the challenges are explained in detail.

• 한국멀티미디어학회논문지
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• 제25권2호
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• pp.297-310
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• 2022

Road facilities such as CCTV poles have potential risk of collision accidents with a car. A collision detection algorithm installed in the facility allows the collision accident to be known remotely. Most collision detection algorithms are operated by simply focusing on whether a collision have occurred, because these methods are used to measure only acceleration data from a 3-axis sensor to detect collision. However, it is difficult to detect other detailed information such as malfunction of the sensor, collision direction and collision strength, because it is not known without witness the accident. Therefore, we proposed enhanced detection algorithm to get the collision direction, and the collision strength from the tilt of the facility after accident using a 9-axis sensor in this paper. In order to confirm the performance of the algorithm, an accuracy evaluation experiment was conducted according to the data measurement cycle and the invocation cycle to an detection algorithm. As a result, the proposed enhanced algorithm confirmed 100% accuracy for 50 weak collisions and 50 strong collisions at the 9-axis data measurement cycle of 10ms and the invocation cycle of 1,000ms. In conclusion, the algorithm proposed is expected to provide more reliable and detailed information than existing algorithm.

• Journal of the Korean Statistical Society
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• 제22권2호
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• pp.147-157
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• 1993

In the survivla analysis the problem of estimating mean residual life function (MRLF) under random censoring is very important. In this paper we propose and study a nonparametric estimator of MRLF, which is a functional form based on the estimator of the survival function due to Susarla and Van Ryzin (1980). The proposed estimator is shown to be better than some other estimators in terms of mean square errors for the exponential and Weibull cases via Monte Carlo simulation studies.

• Nonlinear Functional Analysis and Applications
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• 제29권1호
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• pp.179-195
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• 2024

In this article, we study the Picard-Ishikawa iterative method for approximating the fixed point of generalized α-Reich-Suzuki nonexpanisive mappings. The weak and strong convergence theorems of the considered method are established with mild assumptions. Numerical example is provided to illustrate the computational efficiency of the studied method. We apply our results to the solution of a nonlinear delay integral equation. The results in this article are improvements of well-known results.

• 한국융합학회논문지
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• 제10권10호
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• pp.33-41
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• 2019

본 연구의 목적은 뇌졸중 환자의 운동공포증과 낙상공포 사이에 융합적 관계를 조사하는 것이다. 총 113명의 뇌졸중 환자가 본 연구에 참여하였다. 참여자는 재활병원 입원환자로 낙상 효능감 척도(FES), 운동공포증을 위한 번역된 탐파 척도(TSK-13), 및 활동-특이성 균형 자신감 척도(ABC)를 포함한 3가지 다른 설문지를 작성하도록 요청하였다. TSK-13과 FES는 약한 음의 상관관계를 보였고(r=-0.226), TSK-13과 ABC는 중등도 음의 상관관계가 나타났다(r=0.838). FES는 ABC와 비교했을 때 매우 강한 양의 상관관계가 나타났다(r=0.838). 낙상을 경험한 환자는 낙상을 경험하지 않은 환자보다 유의하게 낮은 FES와 ABC 점수를 보였다(p<0.05). 이 결과는 뇌졸중 환자가 경증 운동공포증을 가지고 있으며, 운동공포증은 낙상공포와 관련이 있음을 제시하고 있습니다. 앞으로 뇌졸중 재활에 있어 운동공포증의 평가가 필요할 것으로 사료된다.

• 한국환경과학회지
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• 제29권4호
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• pp.395-402
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• 2020

This study was conducted to analyze seasonal variations of de-icing salt ions harvested from soils and plants according to salt damage of Pinus densiflora f. multicaulis, a evergreen conifer, on roadsides. Pinus densiflora f. multicaulis was divided into three groups referred to SD, ND, and WD (serious salt damage (SD) = 71-100%, normal salt damage (ND) = 31-70%, and weak salt damage (WD) = 0-30%) based on the degree of visible foliage damage, and measured acidity (pH), electrical conductivity(EC), and de-icing salt ions (K⁺, Ca²⁺, Na⁺, and Mg²⁺) harvested from soils and plants. The results indicated that acidity, electrical conductivity, and de-icing salt ions of soils and plants were significantly affected by seasonal variation and salt damage. In addition, a strong positive liner relationship was observed in plants between the concentration of de-icing salts and salt damage in spring, while the relationship among seasonal variation and salt damage in soil were not significant. The results from this study has important implications for the management of conifer species in relation to salinity and roadsides maintenance.

• 문화기술의 융합
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• 제9권3호
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• pp.1-10
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• 2023

이 연구의 목적은 ANT를 중심으로 창의ˑ융합형 인재 양성 방안을 탐색한 것이다. ANT를 중심으로 창의ˑ융합형 인재를 양성하기 위해서는 첫째, 네트워크 형성단계에서 카오의 법칙을 활용할 필요가 있다. 둘째, 네트워크 형성단계에서 약한 유대의 강한 힘을 활용할 필요가 있다. 셋째, 번역의 4단계 중 문제 제기 단계에서 파문을 일으키기 위해서는 질문하는 능력을 키워야 한다. 넷째, 파문을 던지기 위해서는 다양한 창의적 문제해결 기법 교육이 필요하다. 다섯째, 번역의 4단계 중 2단계인 관심 끌기 단계에서 끼어들기를 성공시키기 위해서는 의사소통 역량과 비판적사고 역량을 교육해야 한다. 후속 연구를 위한 제언은 첫째, ANT에서 제시한 번역의 4단계와 창의적 문제해결 모형단계를 비교 분석해 볼 필요가 있다. 둘째, ANT를 중심으로 구체적인 사례를 적용한 후속 연구들이 있기를 기대한다.

• 한국환경과학회지
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• 제26권5호
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• pp.621-638
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• 2017

Meteorological characteristics related to variations in ozone ($O_3$) concentrations in the Korean peninsula before, during, and after Typhoon Talas (1112) were analyzed using both observation data and numerical modeling. This case study takes into account a high $O_3$ episode (e.g., a daily maximum of ${\geq}90ppb$) without rainfall. Before the typhoon period, high $O_3$ concentrations in the study areas (e.g., Daejeon, Daegu, and Busan) resulted from the combined effects of stable atmospheric conditions with high temperature under a migratory anticyclone (including subsiding air), and wind convergence due to a change in direction caused by the typhoon. The $O_3$ concentrations during the typhoon period decreased around the study area due to very weak photochemical activity under increased cloud cover and active vertical dispersion under a low pressure system. However, the maximum $O_3$ concentrations during this period were somewhat high (similar to those in the normal period extraneous to the typhoon), possibly because of the relatively slow photochemical loss of $O_3$ by a $H_2O+O(^1D)$ reaction resulting from the low air temperature and low relative humidity. The lowest $O_3$ concentrations during the typhoon period were relatively high compared to the period before and after the typhoon, mainly due to the transport effect resulting from the strong nocturnal winds caused by the typhoon. In addition, the $O_3$ increase observed at night in Daegu and Busan was primarily caused by local wind conditions (e.g., mountain winds) and atmospheric stagnation in the wind convergence zone around inland mountains and valleys.