• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.3
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• pp.298-305
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• 2019

The demand for the revitalization of marine tourism in Busan North Port is increasing due to changes in functions such as an increase in harbor traffic volume and the expansion of marine leisure space in Busan. As a result, Busan City plans to set a phased alleviation target for prohibition of cruise ship operations, and to lift the prohibition of excursion ship operations in North Port following the cancellation of the prohibition of excursion ship operations in South Port in 2017. The purpose of this study is to evaluate the risk of excursion ship operations in Busan North Port by applying the marine traffic assessment index and to examine the possibility of excursion ship operations. For this purpose, port status, marine accidents, and traffic flow of Busan North Port were investigated. In addition, marine traffic assessment indexes, such as traffic congestion, risk based on an ES Model, and IWRAP MkII, a maritime risk assessment tool, were used to assess the risk and possibility of excursion ship operations in Busan North Port. This study can be used as basic data for analyzing the risk factors that may occur when excursion ships are operated in Busan North Port and to define how excursion ships should operate, with related safety measures.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.30.3-30.3
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• 2021

In order to generate the 3D structure of the 21-cm signal during the reionization, semi-numerical simulations based on Excursion set formalism are broadly used. However, semi-numerical simulations in the realization of the 3D structure are known to be the ionizing photon non-conserving by the structure of the Excursion set approach. Recently, explicit photon conserving algorithms for semi-numerical simulations introduced, but they are still too slow when forward modelling the 21-cm signal with high-dimensional parameter spaces. Here, we introduce a new method for approximately correcting photon non-conservation, which can be applied on-the-fly. This method is tailored towards the efficient simulation and Bayesian inference with high-dimensional parameter space. Then, we investigate how large an impact that photon non-conservation has on astrophysical parameter inference by performing an MCMC analysis. We find that the ionizing escape parameter is deviated from the fiducial value by 2 sigma when we infer astrophysical parameters without this correction.

• Journal of the Korean Statistical Society
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• v.36 no.4
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• pp.479-488
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• 2007

The elliptic random field is an extension to the Gaussian random field. We proved a theorem which characterizes the elliptic random field. We proposed a heuristic approach to derive an approximation to the distribution of the size of one connected component of its excursion set above a high threshold. We used this approximation to approximate the distribution of the largest cluster size. We used simulation to compare the approximation with the exact distribution.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.44.3-45
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• 2021

일반화된 excursion set 이론과 자기 유사 구형 유입(Self-similar spherical infall) 모형에 기반하여 Splashback 질량함수에 대한 해석적 단일 매개변수 모델을 착안하였다. Planck/WMAP7 관측결과를 토대로 구축된 EREBOS N-Body 시뮬레이션의 수치적 결과의 해석적 모델을 이용한 회귀분석을 통해 단일 매개변수이자 Splashback 경계의 확산적 특성을 수치화하는 확산계수(Diffusion Coefficient)의 추정치를 계산하였다. 계산된 확산계수를 적용한 해석적 모델과 수치적 결과가 5 ≤ M/(10¹²h^-1 M_⊙) < 10³의 질량범위에서 매우 근접히 일치하는 것을 보였으며 Baysian and Akaike Information Criterion 검정을 통해 0.3 ≤ z ≤ 3의 범위에서 기존의 모델들보다 본 모델이 선호 돼야함을 확인하였다. 또한 확산계수가 적색편이에 대하여 선형진화에 근접한 변화를 보임을 발견하였으며, 특정 임계 적색편이(z_c)를 기준으로 확산계수가 0에 수렴함을 발견하였다. 더 나아가 두 Planck모델과 WMAP7모델에서 도출된 확산계수는 서로 상당한 차이를 보였다. 이 결과는 암흑물질 헤일로의 splashback 질량함수가 z ≥ z_c에서 매개변수가 없는 온전한 해석적 모델로 설명되고 z_c가 독립적으로 우주의 초기조건을 독립적으로 특정지을 수 있는 가능성을 지님을 시사한다. 이 초록은 The Astrophysical Journal의 Ryu & Lee 2021, ApJ, 917, 98 (arxiv:2103.00730) 논문을 바탕으로 작성되었다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.2
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• pp.92-102
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• 2004

In this paper, an analytical solution of calculating the excess temperature field due to a point heat source is presented in the presence of spring-neap modulation of convective alongshore flow. The basic form of the solution is identical to that given by Jung et al. (2003) but the convective term in the exponential kernel function is extended and a spring-neap variation in the horizontal eddy diffusivity is newly introduced. A set of calculations have been performed to examine the sensitivity of the heat build-up to the change in current fields and turbulent dispersion. Results indicate that the excess temperature field is confined within the tidal excursion distance, while the excess temperature field beyond the distance is mainly controlled by the horizontal diffusion. The heat build-up within the distance is considerably affected by the spring-neap variation in the horizontal eddy diffusivity; the relatively high excess temperature more than 1$^{\circ}C$ is extended further when the eddy diffusivity has spring-neap modulation.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.1
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• pp.125-134
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• 2019

Purpose : The purpose of this study was to investigate the effects of stabilization exercise and breathing exercise on the flexion relaxation phenomenon (FRP) and respiratory parameters in patients with chronic low back pain. Methods : We randomly allocated 30 chronic low back pain patients (CLBP) to a stabilization exercise (SE) group (n=15) and a breathing exercise (BE) group (n=15). FRP was measured using surface electromyography (SEMG). Thoracic excursion was measured with a cloth tape measurement technique. The SE group participated in a stabilization exercise program and the BE group participated in a breathing exercise program three times a week for 12 weeks. The data was analyzed using paired t-tests for comparisons of flexion relaxation ratio (FRR) and respiratory variables. Independent t-tests were used for comparison of inter-group FRR and respiratory variables. The significance level was set at .05. Results : FRP variables-ES FRR (Flex/MVF), ES FRR (Ext/MVF), MF FRR (Flex/MVF), and MF FRR (Ext/MVF) values-increased significantly after exercise in both the SE and BE groups (p<.05). The thoracic excursion measurements after exercise increased significantly in both groups (p<.001). VAS values decreased significantly in both groups (p<.001). There were no significant differences between the two groups in FRP variables-ES FRR (Flex/MVF), ES FRR (Ext/MVF), MF FRR (Flex/MVF), and MF FRR (Ext/MVF)-or VAS values after exercise (p>.05). For thoracic excursion after exercise, the BE group was significantly higher than the SE group (p<.001). Conclusion : We found that FRP and respiratory variables increased significantly after SE and BE for 12 weeks in CLBP. Thoracic excursion-a respiratory variable-suggests that treatment was more effective in the BE group than the SE group.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.1-10
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• 2019

Purpose : To investigate the relationship between breathing pattern disorder and joint position error (JPE) in patients with chronic low back pain (CLBP). Methods : Thirty nine patients with CLBP participated. End-tidal $CO_2$ and respiration rate (RR) were measured using a capnography. Breathing-hold time (BHT) and Nijmegen Questionnaire (NQ) were investigated. Thoracic excursion was measured with a cloth tape measurement technique. Joint position error were measured using a small laser point mounted on a lightweight headband. they were asked to relocate the head, after the neck movement on the horizontal plane. Pearson 's test was used for correlation analysis between respiratory variables and JPE in patients with CLBP. Independent t-test was used to verify the difference between thoracic and diaphragm breathing pattern in patients with CLBP. The significance level was set at 0.05. Results : There was a significant correlation between JPE (LR) and JPE (RR, EX) (r=.639, r=.813) (p<.001) and a low negative correlation with end-tidal $CO_2$ (r=-.357) (p<.05). There was a significant correlation between RR and JPE (EX) (r=.750) (p<.001). There was a low correlation between JPE (EX) and NQ (r=.333) (p<.05). There was a somewhat high negative correlation between NQ and thoracic excursion (r=-.528) (p<.001). There was a somewhat high negative correlation between thoracic excursion and JPE (LR, RR, EX) (r=-.470, r=-.484, r=-.602) (p<.001). There were no significant differences in the RR, BHT, NQ, and thoracic excursion between the thoracic and diaphragmatic breathing (p>.05). There was a significant difference in the JPE (EX), end - tidal $CO_2$, and VAS values between the thoracic and diaphragm breathing (p<.05). Conclusion : There was a correlation between JPE (EX) and NQ in patients with CLBP, and correlation between thoracic excursion and JPE (LR, RR, EX) and NQ. There was a significant difference in the JPE (EX), end-tidal $CO_2$ level, and VAS value in the comparison of thoracic breathing and diaphragm breathing. The results showed that breathing patterns and JPE were related to each other.

• Physical Therapy Rehabilitation Science
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• v.12 no.3
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• pp.320-326
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• 2023

Objective: The purpose of this study is to investigate the impact of visual biofeedback methods utilizing pressure sensors on the static balance of stroke patients. Design: Randomized crossover study. Methods: A total of 27 patients with hemiparesis participated in this study. The following three feedback conditions were considered: condition 1 (Knowledge of performance feedback), condition 2 (Knowledge of result feedback), and condition 3 (None feedback). A force plate was used to measure static balance. The total sway length, average sway velocity, x-axis excursion, and y-axis excursion of the center of pressure were measured. One-way repeated-measures analysis of variance was employed for comparisons of variables between each condition. The statistical significance level was set at α = 0.05 for all analyses. Results: There was a significant difference in the static balance results between each feedback condition (p<0.05). In the post-hoc results, it was confirmed that the static balance was significant in the order of knowledge of performance feedback, knowledge of result feedback, and none feedback. Conclusions: When comparing the three conditions, it was observed that knowledge of performance feedback showed the most improved effect on static balance ability. As further research progresses, that this approach could be used as an effective intervention method in clinical settings.

• Nuclear Engineering and Technology
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• v.34 no.2
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• pp.117-131
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• 2002

Core disruptive accidents have been investigated at Korea Atomic Energy Research Institute(KAERI) as part of the work to demonstrate the inherent and ultimate safety of conceptual design of the Korea Advanced Liquid Metal Reactor(KALIMER), a 150 MWe pool- type sodium cooled prototype fast reactor that uses U-Pu-Zr metallic fuel. In this study, a simple method and associated computer program, SCHAMBETA, was developed using a modified Bethe-Tait method to simulate the kinetics and thermodynamic behavior of a homogeneous spherical core over the period of the super-prompt critical power excursion induced by the ramp reactivity insertion. Calculations of the energy release during excursions in the sodium-voided core of the KALIMER were subsequently performed using the SCHAMBETA code for various reactivity insertion rates up to 100 S/s, which has been widely considered to be the upper limit of ramp rates due to fuel compaction. Benchmark calculations were made to compare with the results of more detailed analysis for core meltdown energetics of the oxide fuelled fast reactor. A set of parametric studies were also performed to investigate the sensitivity of the results on the various thermodynamics and reactor parameters.

• Journal of the Korean Professional Engineers Association
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• v.19 no.1
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• pp.25-32
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• 1986

The number of visiters to Bukhan Mt. national park, generation quantity of solid waste and collection system were researched to consider a counterplan for the pollution control of the national park and study for developing the effective treatment of solid waste was tried through the proximate analysis of each component containing. Results obtained in this study were summerized as follows; The great part of visitors go on an excursion to the Bukhan Mt. national park during July and August and also, the solid waste was generated nearly a half of the total amount at the same period. The major collection facilities in the national park were waste basket and incineration box. But the incineration box was too large in volume and very far in distance, and its collection period was irregular, so it was cause to the congestion of solid waste and bad smell and dirty. Therefore, to complete collection of solid waste, we must set up the waste basket which able to find within 40～50m from the origination place of solid waste and induce the visitors to throw the solid waste. It was obtained as moisture content: 48.5 wt%, volatile solid: 28.4wt％, fixed solid: 23.1 wt％, lower heating value: 1,320kca1/kg from experimental analysis of solid waste. According to this analysis, the incineration operation is possible, but the generation quantity of solid waste was too small to construct incineration plant for heat recovery. It was found that it is suitable for the aerobic composting by mixing with the night soil which generate in the national park after the recovery of resources such as metals, glasses and plastics.