• Title/Summary/Keyword: 적천수

Search Result 466, Processing Time 0.031 seconds

Accuracy Evaluation of Dispersion-Correction Finite Difference Model for Tsunami Propagation (지진해일 전파 분산보정 유한차분모형의 정밀도 평가)

  • 윤성범;임채호;조용식;최철순
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.14 no.2
    • /
    • pp.116-127
    • /
    • 2002
  • Most of finite difference numerical models for the simulation of tsunami propagation developed so for are based on the shallow-water equations which are frequently solved by the leap-frog scheme. If the grid size is properly selected, this numerical scheme gives a correct dispersion effect fur constant water depth. However, if the water depth changes, the dispersion effect of tsunamis can not be accurately considered at every grid point in the whole computational domain. In this study we improved the existing two-dimensional dispersion-correction finite difference numerical scheme. The present scheme satisfies the local dispersion relationships of tsunamis propagating over a slowly varying topography while using uniform grid size and time step. To verify the applicability of the improved numerical model, a tsunami due to 1983 East Sea central earthquake is simulated for Korean harbors with the tide gage records such as Sokcho, Mukho, Pohang and Ulsan in the East Sea. Numerical results of the 1983 tsunami are compared with the measured data and the accuracy of the present numerical model is evaluated.

Computation of Wave Height Distribution Inside a Harbor Using Time-Dependent Mild-Slope Equation (시간의존 완경사방정식을 이용한 항내 파고분포 계산)

  • 곽문수;홍길표;편종근
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.2 no.1
    • /
    • pp.18-27
    • /
    • 1990
  • The calmness inside a harbor plays an important role in the appropriate disposition of har-bor structures. However, it is not easy to get the accurate computational results because they are affected by many factors concerning with the wave transformation. Successful solution also depends on determining the boundary values appropriately. This paper presents the numerical model which is able to calculate wave heights inside a harbor It is based upon the time-dependent mild-slope equation involving wave refraction, diffraction, shoaling effect and reflection. In particular, the arbitrary reflectivity is used at the boundary in order to simulate the real harbor reflection condition. This numerical model is applied for Hupo-Harbor and its validities are investgated by comparing with experimental values from the hydraulic model test as well as computational results from Taka-yama's numerical model (1981). It is shown that the model results are in good agreement with results from hydraulic model and Takayama's.

  • PDF

Effect of Hot Water Extract of Alnus japonica Steud on the Experimentally-induced Acute Gastritis and Peptic Ulcers in Rats (오리나무 열수 추출물이 실험적으로 유발된 흰쥐의 위염 및 위궤양에 미치는 영향)

  • Na, Chun-Soo;Lee, Sang-Bum;Kim, Jin-Bum;Chung, Ha-Sook;Dong, Mi-Sook
    • Korean Journal of Pharmacognosy
    • /
    • v.43 no.1
    • /
    • pp.72-78
    • /
    • 2012
  • Alnus japonica Steud (A. japonica) have long been used in the traditional medicine for gastric disorder, hepatitis and fatty liver in Korea. Antiulcer effects of A. japonica hot water extract (AJ ext) were evaluated by in vitro antibacterial activity against H. pylori, by the inhibitory action against the in vitro gastric $H^+/K^+$-ATPase and using rat models of gastric mucosal damage and gastric ulcer induced by HCl-ethanol, indomethacin, and restraint and water-immersion stress. For the determination of antibacterial activity of AJ ext against H. pylori, the activity of urease which released from H. pylori was measured in culture. AJ ext showed weak antibacterial activity against H. pylori with the growth inhibitions of 37% and 61% by adding final concentrations of 500 and $1000{\mu}g/ml$ culture, respectively at 24 h. To observe the inhibitory activity of AJ ext against the $H^+/K^+$-ATPase in hog gastric membrane vesicle, $IC_{50}$ value of AJ ext was $806.3{\mu}g/ml$. Pretreatment of AJ ext (200, 500 mg/kg, p.o.) prevented in a dose-dependent manner the acute gastritis in HCl-ethanol model and the formation of gastric ulcer in indomethacin model and restraint and water-immersion stress model. These results suggest that the AJ ext can be used for prevention and treatment of gastric mucosal damage and ulcers induced by various stress.

Optmized Design for Flood Mitigation at Sea Side Urban Basin (해안 도시유역의 수재해 저감설계 최적화 기법 연구)

  • Kim, Won Bum;Kim, Min Hyung;Son, kwang Ik;Jung, Woo Chang
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2016.05a
    • /
    • pp.267-267
    • /
    • 2016
  • Extreme events, such as Winnie(1987), Rusa(2002), Maemi(2003) at sea-side urban area, resulted not only economic losses but also life losses. The Korean sea-side characterisitcs are so complicated thar the prediction of sea level rise makes difficult. Geomophologically, Korean pennisula sits on the rim of the Pacific mantle so the sea level is sensitive to the surges due to earth quake, typoon and abnormal climate changes. These environmetns require closer investigation for the preparing the inundatioin due to the sea level rise with customized prediction for local basin. The goal of this research is provide the information of inundation risk so the sea side urban basin could be more safe from the natural water disastesr.

  • PDF

Effect of Nursing Work Environment on Turnover Intention of Nurses in Long-Term Care Hospitals: The Mediating Effect of COVID-19 Stress (요양병원 간호사의 간호근무환경과 이직의도 관계: COVID-19 심리적 스트레스의 매개효과)

  • Lee, Eun Joo;Cheon, Soo Yeon;Lee, Jung Hwa
    • Korean Journal of Occupational Health Nursing
    • /
    • v.31 no.1
    • /
    • pp.22-30
    • /
    • 2022
  • Purpose: This study aimed to identify the mediating effect of Psychological stress of COVID-19 stress on the relationship between nursing work environment and turnover intention of nurses in long-term care hospitals. Methods: The participants were 176 nurses working at three long-term care hospitals in Changwon City. Data were collected from August 11 to 14, 2021, using self-report questionnaires. The data were analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation coefficients, and hierarchical regression, using the SPSS 23.0 software. A mediation analysis was performed according to the Baron and Kenny's test, and Sobel test. Results: Turnover intention was positively correlated with Psychological stress of COVID-19 stress (r=.23, p=.002) and negatively correlated with nursing work environment (r=-.44, p<.001). Psychological stress of COVID-19 stress had a significantly negative relationship with nursing work environment (r=-.15, p=.045). Psychological stress of COVID-19 stress partially mediated the relationship between nursing work environment and turnover intention. Conclusion: The findings of this study indicate that a positive nursing work environment can help nurses reduce their Psychological stress of COVID-19 stress and turnover intention. To reduce the turnover intention among nurses' in long-term care, it is necessary to promote better work environments suitable for COVID-19 and to establish detailed strategies for reducing their physiological stress.

Study on Prediction of Net Thrust of Multi-Pod-Driven Ice-Breaking Vessel Under Bollard Pull and Overload Conditions According to the Change of Water Depth Using Computational Fluid Dynamics-Based Simulations (수심 변화에 따른 볼라드 당김 및 과부하 조건에서의 다중 포드 추진 쇄빙선박의 여유추력 추정에 대한 수치해석적 연구)

  • Kim, JinKyu;Kim, Hyoung-Tae;Kim, Hee-Taek;Lee, Hee-Dong
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.58 no.3
    • /
    • pp.158-166
    • /
    • 2021
  • In this paper, a numerical analysis technique using a body force model is investigated to estimate the available net thrust of multi-pod-driven ice-breaking vessels under bollard pull and overload conditions. To employ the body force model in present flow simulations, drag and thrust components acting on the pod unit are calculated by using Propeller Open Water (POW) test data. The available net thrusts according to the direction of operation are evaluated in both bollard pull and overload conditions under deep water. The simulation results are compared with the model test data. The available net thrusts, calculated by the present analysis for ahead operating modes at 3~6 knots which are typical speeds of the target vessel in arctic field, are agreed well with the model test results. It is also found that the present result for astern operating mode appears approximately 6 % larger than the model test result. In addition, the available net thrusts are calculated under the both operating conditions accompanied by shallow water effects, and the main cause of the difference is studied. Based on the result of the present study, it is confirmed that the body force model can be applied to the performance evaluation of multi-pod propulsion system and the main engine selection in early design stage of the vessel.

A Study on the RPA Interface Method for Hybrid AI Chatbot Implementation (하이브리드 AI 챗봇 구현을 위한 RPA연계 방안 연구)

  • Cheonsu, Jeong
    • KIPS Transactions on Software and Data Engineering
    • /
    • v.12 no.1
    • /
    • pp.41-50
    • /
    • 2023
  • Recently, as the Coronavirus disease 2019 (COVID-19) prolongs along with the development of artificial intelligence technology, a non-contact society has become commonplace. Many companies are promoting digital transformation and the activation of artificial intelligence introduction to respond to this which leads to dramatic increase of demand for Chatbot. In addition, a Chatbot has reached the point of processing business transactions from responding simple inquiries. However, it is necessary to develop an API to interface with the legacy system and there are many difficulties in connecting. To solve this, it is becoming important to establish a hybrid Chatbot environment through RPA interface. Recently, the combination of RPA and Chatbot is considered an effective tool for handling many business processes. But, there are many difficulties due to the lack of interface cases and the difficulty in finding a method to development them. This study suggests a method for building a hybrid Chatbot which is an interface Chatbot(Conversational UX) and RPA(Task Automation) from the perspective of hyper-automation based on actual development cases and review of literature review is presented, so that the interface method can be understood and develop more easily. Therefore, there are implications for actively using AI Chatbot for digital transformation.

Sensitivity analysis of factors affecting 2D calculation in inundation analysis by using XP-SWMM (XP-SWMM을 이용한 침수 분석 시 2차원 계산에 영향을 미치는 인자에 대한 민감도 분석)

  • Sun, Dongkyun;Kang, Taeuk;Lee, Sangho
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2021.06a
    • /
    • pp.339-339
    • /
    • 2021
  • XP-SWMM은 유역의 강우-유출과 1차원 관망 해석 및 2차원 지표면 흐름 해석이 가능하여 도시지역의 침수 모의에 활용도가 높다. 하지만 대부분의 수학적 모형이 그러하듯 XP-SWMM은 많은 입력 변수를 포함하고 있어 사용자의 숙련도에 따라 모의 결과가 달라질 수 있다. 본 연구의 목적은 XP-SWMM을 이용한 침수 모의의 정확도를 향상시키기 위해 침수 모의에 영향을 줄 수 있는 인자를 검토하고, 민감도 분석을 통해 인자별 적정 범위를 제안하는 것이다. 다만, 유역의 강우-유출과 1차원 관망 해석에 사용되는 매개변수는 과거 많은 연구자들이 적정 범위를 제시하였으므로 본 연구에서는 2차원 지표면 흐름 해석에 관한 입력 변수만을 대상으로 하였다. 이를 위해 2차원 계산의 지배방정식인 천수방정식의 매개변수 중 XP-SWMM에서 제어할 수 있는 인자와 XP-SWMM의 사용자 편의환경(graphical user interface; GUI)에서 제어 가능한 인자를 고려하였다. 선정된 인자는 지표면 조도계수, 2차원 계산 시간 간격, 2D 집수유량 계수, Smagorinsky 계수, Wet/dry 깊이이다. 제시된 인자들을 대상으로 침수흔적도의 침수 면적을 기준으로 민감도 분석을 수행하였고, 인자의 변화율을 침수 면적의 변화율로 변화시키는 조건수(condition number)를 활용하여 인자별 민감 여부를 분석하였다. 또한, 영향 인자 변화에 따른 침수 면적과 침수흔적도의 상대오차를 분석하여 영향 인자의 적정 범위를 제안하였다. 그 결과, 지표면 조도계수의 적정범위는 0.02~0.05, 2차원 계산 시간 간격은 0.1-3.5초, Smagorinsky 계수는 0.06~1.0, Wet/dry 깊이는 0.001~0.02 m인 것으로 나타났다. 본 연구는 XP-SWMM을 이용한 2차원 침수 모의에 활용될 수 있는 영향 인자와 적정 범위를 제안한 연구로서, 향후 XP-SWMM을 이용한 많은 침수분석에 참고자료로 활용될 수 있을 것으로 판단된다.

  • PDF

옻나무 유래 Flavonoid처리가 흰쥐 Leydig 세포의 체외배양에서 Testosterone분비에 미치는 영향

  • 성환후;최선호;민관식;장유민;나천수;정일정
    • Proceedings of the KSAR Conference
    • /
    • 2001.03a
    • /
    • pp.80-80
    • /
    • 2001
  • 옻나무 유래 Flavonoid(F)는 항암 효과, 숙취해소 등의 효능이 있으며, 신장의 기능을 촉진하고 생식에도 영향을 준다고 알려져 있다. 그 주성분으로는 fustin, fisetin, sulfuretin, butein으로 추정되고 있다. 본 연구팀의 예비실험에서 성숙 흰쥐에게 F를 30일간 5mg씩 구강투여 하여 정소 중량 및 혈액 내 Testosterone 농도를 분석한 결과, 정소 중량이 증가되고 혈중 Testosterone의 농도도 대조구에 비해 유의적으로 높은 결과를 얻었다. 이에 본 연구의 목적은 옻나무 유래 F가 성숙 수컷 횐쥐의 생식 기능에 직접 미치는 영향을 알아보고자, 흰쥐 Leydig 세포를 분리, 회수하여 체외배양에서 Testosterone농도를 조사하였다. SD계 흰쥐(약 12주령, 체중 250g 전후)의 정소를 적출 한 후, Leydig 세포를 회수하기 위해 0.25% collagenase용액에 넣어 34$^{\circ}C$에서 15분간 진탕 수조에서 배양하였다. 배양된 정소조직은 D-MEM 배양액(10% FCS와 antibiotics 첨가)으로 2~3회 세척한 후 세포 수를 1$\times$$10^{6}$ cells/$m\ell$/well로 분주하여, F(20, 40, 80, 160ng), IGF-I(50, 100ng) 와 LH(10, 100ng) 용량별 각각 첨가하여 배양하였다. 각 처리 후, 배양시간(3, 6, 12, 24, 36시간)에 따라 배양액을 회수하여 COAT-A-COUNT(DPC, USA) kit를 이용하여 RIA방법에 의해 Testosterone을 분석한 결과는 다음과 같다. 대조구 Leydig 세포를 36시간까지 체외 배양하여 Testosterone의 농도를 조사한 결과, 24시간 배양구가 가장 높은 농도를 나타내었다. F를 단독 첨가하여 12시간 배양한 실험에서 F 80ng 첨가구에서 유의적으로 높은 농도를 보였다. LH 10ng 및 100ng 첨가구의 시간별 변화로는, LH 10ng 첨가구에서는 6~12시간 이후, LH 100ng 첨가구에서는 3~6시간 사이에서 유의적인 증가를 보였다. 또한, LH 10ng 첨가 실험에서는 LH 10ng+F 40ng에서 12시간 배양 시, 유의적으로 높은 Testosterone 분비를 확인하였으며, LH 100ng을 첨가하여 3시간 배양 시는 각 처리구 마다 높은 유의적 차이를 보였다. 한편, GH에 관여하는 IGF-I 첨가효과를 비교 검토한 결과, LH 100ng+IGF-I 100ng, 6시간 배양구에서 유의적으로 높게 나타내었다. 이상의 결과로, F 단독 처리 시의 적정량은 약 80ng이며, 흰쥐 정소 Leydig 세포의 Testosterone분비를 촉진하는 작용을 하는 것으로 사료되며, 특히 LH+F구에서 Testosterone분비를 더욱 향상시킴으로써 정소 Leydig 세포의 Androgen 생성을 촉진시키는 역할이 있는 것으로 보여진다 따라서 옻나무 유래 F는 포유동물의 생식기능에 중요하게 작용하는 것으로 사료된다.

  • PDF

Numerical Comparisons of Flow Properties Between Indivisual and Comprehensive Consideration of River Inundation and Inland Flooding (하천범람과 내수침수의 개별적·복합적 고려에 따른 흐름 특성의 수치적 비교)

  • Choi, Sang Do;Eum, Tae Soo;Shin, Eun Taek;Song, Chang Geun
    • Journal of Convergence for Information Technology
    • /
    • v.10 no.10
    • /
    • pp.115-122
    • /
    • 2020
  • Due to the climate change, torrential rain downpours unprecedentedly, and urban areas repeatedly suffer from the inundation damages, which cause miserable loss of property and life by flooding. Two major reasons of urban flooding are river inundation and inland submergence. However, most of previous studies ignored the comprehensive mechanism of those two factors, and showed discrepancy and inadequacy due to the linear summation of each analysis result. In this study, river inundation and inland flooding were analyzed at the same time. Petrov-stabilizing scheme was adopted to capture the shock wave accurately by which river inundation can be modularized. In addition, flux-blocking alrotithm was introduced to handle the wet and dry phenomena. Sink/source terms with EGR (Exponentially Growth Rate) concept were incorporated to the shallow water equations to consider inland flooding. Comprehensive simulation implementing inland flooding and river inundation at the same time produced satisfactory results because it can reflect the counterbalancing and superposition effects, which provided accurate prediction in flooding analysis.