• Title/Summary/Keyword: PNU

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Development of Particle Simulation Method for Analysis of Fluid-Structure Interaction Problems (유체-구조 상호연성 해석을 위한 입자법 시뮬레이션 기술 개발)

  • Hwang, Sung-Chul;Park, Jong-Chun;Song, Chang-Yong;Kim, Young-Hun
    • Journal of Ocean Engineering and Technology
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    • v.27 no.2
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    • pp.53-58
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    • 2013
  • Recently, some fluid-structure interaction (FSI) problems involving the fluid impact loads interacting with structures, such as sloshing, slamming, green-water, etc., have been considered, especially in the ocean engineering field. The governing equations for both an elastic solid model and flow model were originally derived from similar continuum mechanics principles. In this study, an elastic model based on a particle method, the MPS method, was developed for simulating the FSI problems. The developed model was first applied to a simple cantilever deflection problem for verification. Then, the model was coupled with the fluid flow model, the PNU (Pusan National University modified)-MPS method, and applied to the numerical investigation of the coupling effects between a cantilever and a mass of water, which has variable density, free-falling to the end of the cantilever.

The Effects of Neonatal Massage on Weight Gain, Vital Signs and Stress Hormone of low Birth Weight (신생아마사지가 저체중아의 체중, 활력징후 및 스트레스호르몬에 미치는 영향)

  • Kim, Y.H.;Choi, S.Y.;Jeong, G.S.;Park, H.K.;Lee, D.W.
    • Korean Parent-Child Health Journal
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    • v.2
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    • pp.30-52
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    • 1999
  • The purpose of this study is to clarify that neonatal massage is a nursing intervention which is desirable to LBW by making nurses provide such massage service to LBW hospitalized at NICU and confirming effects of the service on weight gain, vital signs and stress hormones(cortisol, norepinephrine, epinephrine). The data were collected from Dec. 14, 1998 to Oct. 4, 1999. The subjects were 28 LBW infants. The data were analyzed with the SAS program with T-test, Chi-square test and ANOVA. 1. The Experimental group that received neonatal massage showed a higher daily gain of weight than the comparative group. Weight gain for 10 days and weight gain of seven days after the massage were also higher in the former group than in the latter, indicating that there are statistically significant differences between the two groups.

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The Prediction of Resistance of a 23m Class Planing Hull

  • Yang, Seung-Il;Shin, Myung-Soo;Park, Yong-Jea;Min, Keh-Sik;Kim, Jae-Shin;Kim, Hyo-chul;Hong, Sung-Wan;Lee, Seung-Hee;Lee, Young-Gill;Chung, Jung-Han
    • Journal of Hydrospace Technology
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    • v.2 no.2
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    • pp.68-79
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    • 1996
  • The present report describes the results of the cooperative experimental study organized by the High-Speed Marine Vehicle Committee of the Korea Towing Tank Conference. The study aims to improve model test technique and accuracy and to self-evaluate their own capabilities. The resistance tests of a 23m class planing hull were performed at the towing tanks of the Korea Research Institute of Ships and Ocean Engineering (KRISO), Hyundai Maritime Research Institute (HMRI), Seoul National University (SNU), Inha University (IU) and Pusan National University (PNU). In addition, the longitudinal wave cut was measured antral and analyzed at the KRISO. All the results of total resistance, trim and mean sinkage are presented in this report and the results show fairly good agreements comparing with the ITTC HSMV committee's report.

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Influence of porosity and axial preload on vibration behavior of rotating FG nanobeam

  • Ehyaei, Javad;Akbarshahi, Amir;Shafiei, Navvab
    • Advances in nano research
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    • v.5 no.2
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    • pp.141-169
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    • 2017
  • In this paper, a nanobeam connected to a rotating molecular hub is considered. The vibration behavior of rotating functionally graded nanobeam based on Eringen's nonlocal theory and Euler-Bernoulli beam model is investigated. Furthermore, axial preload and porosity effect is studied. It is supposed that the material attributes of the functionally graded porous nanobeam, varies continuously in the thickness direction according to the power law model considering the even distribution of porosities. Porosity at the nanoscopic length scale can affect on the rotating functionally graded nanobeams dynamics. The equations of motion and the associated boundary conditions are derived through the Hamilton's principle and generalized differential quadrature method (GDQM) is utilized to solve the equations. In this paper, the influences of some parameters such as functionally graded power (FG-index), porosity parameter, axial preload, nonlocal parameter and angular velocity on natural frequencies of rotating nanobeams with pure ceramic, pure metal and functionally graded materials are examined and some comparisons about the influence of various parameters on the natural frequencies corresponding to the simply-simply, simplyclamped, clamped-clamped boundary conditions are carried out.

Precise Geoid Model for Korea from Gravity and GPS Data

  • Choi, Kwang-Sun;Won, Ji-Hoon;Shin, Young-Hong
    • Journal of the Korean Geophysical Society
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    • v.9 no.3
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    • pp.181-188
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    • 2006
  • The data, methodology, and the resulting accurate gravimetric geoid model for the Korean Peninsula (latitude from 32˚ N to 40˚ N and longitude from 124˚ E to 131˚ E) are presented in this study. The types of used data were a high degree geopotential model (the EGM96 spherical harmonic coefficient set), a set of 12,615 land gravity observations, 1,056,075 shipborne gravity observations, and KMS2002 gravity anomalies from satellite altimetry. The remove-restore technique was successfully applied to combining the above mentioned data sets using up to degree and order 112 of the EGM96 coefficient. The residual geoid was calculated with residual Free-Air anomaly values using the spherical Stokes' formula with a 37-km integration cap radius. The geoid model was referred to WGS84 geodetic system and was tested using a set of GPS/levelling geoid undulations. The absolute accuracy is 0.132 m and some improvement compared to the PNU95 geoid model was found.

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The Cubic-Interpolated Pseudo-Particle Lattice Boltzmann Advection-Diffusion Model (이류확산 방정식 계산을 위한 입방보간유사입자 격자볼츠만 모델)

  • Mirae, Kim;Binqi, Chen;Kyung Chun, Kim
    • Journal of the Korean Society of Visualization
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    • v.20 no.3
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    • pp.74-85
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    • 2022
  • We propose a Cubic-Interpolated Pseudo-Particle Lattice Boltzmann method (CIP-LBM) for the convection-diffusion equation (CDE) based on the Bhatnagar-Gross-Krook (BGK) scheme equation. The CIP-LBM relies on an accurate numerical lattice equilibrium particle distribution function on the advection term and the use of a splitting technique to solve the Lattice Boltzmann equation. Different schemes of lattice spaces such as D1Q3, D2Q5, and D2Q9 have been used for simulating a variety of problems described by the CDE. All simulations were carried out using the BGK model, although another LB scheme based on a collision term like two-relation time or multi-relaxation time can be easily applied. To show quantitative agreement, the results of the proposed model are compared with an analytical solution.

Suggestion for deep learning approach to solve the interference effect of ammonium ion on potassium ion-selective electrode

  • Kim, Min-Yeong;Heo, Jae-Yeong;Oh, Eun Hun;Lee, Joo-Yul;Lee, Kyu Hwan
    • Journal of the Korean institute of surface engineering
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    • v.55 no.3
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    • pp.156-163
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    • 2022
  • An ammonium ion with a size and charge similar to that of potassium can bind to valinomycin, which is used as an ion carrier for potassium, and cause a meaningful interference effect on the detection of potassium ions. Currently, there are few ion sensors that correct the interference effect of ammonium ions, and there are few studies that specifically suggest the mechanism of the interference effect. By fabricating a SPCE-based potassium ion-selective electrode, the electromotive force was measured in the concentration range of potassium in the nutrient solution, and the linear range was measured to be 10-5 to 10-2 M, and the detection limit was 10-5.19 M. And the interference phenomenon of the potassium sensor was investigated in the concentration range of ammonium ions present in the nutrient solution. Therefore, a data-based analysis strategy using deep learning was presented as a method to minimize the interference effect.

Buckling analysis of FG plates via 2D and quasi-3D refined shear deformation theories

  • Lemya Hanifi Hachemi Amar;Fouad Bourada;Abdelmoumen Anis Bousahla;Abdelouahed Tounsi;Kouider Halim Benrahou;Hind Albalawi;Abdeldjebbar Tounsi
    • Structural Engineering and Mechanics
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    • v.85 no.6
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    • pp.765-780
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    • 2023
  • In this work, a novel combined logarithmic, secant and tangential 2D and quasi-3D refined higher order shear deformation theory is proposed to examine the buckling analysis of simply supported uniform functionally graded plates under uniaxial and biaxial loading. The proposed formulations contain a reduced number of variables compared to others similar solutions. The combined function employed in this study ensures automatically the zero-transverse shear stresses at the free surfaces of the structure. Various models of the material distributions are considered (linear, quadratic, cubic inverse quadratic and power-law). The differentials stability equations are derived via virtual work principle with including the stretching effect. The Navier's approach is applied to solve the governing equations which satisfying the boundary conditions. Several comparative and parametric studies are performed to illustrates the validity and efficacity of the proposed model and the various factors influencing the critical buckling load of thick FG plate.

Impact of US-China Trade War on Stock Price of Korean Exporting Firms (미·중 무역분쟁이 한국 수출기업 주식가격에 미치는 영향)

  • Yoo-Kyung Won;Chae-Deug Yi
    • Korea Trade Review
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    • v.45 no.1
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    • pp.173-201
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    • 2020
  • As the US's trade deficit with China and China's manufacturing industry has risen rapidly, the US has begun to regulate trade items as part of China's checks. Four rounds of reprisal measures have greatly altered the trade structures of both countries. In particular, Korea, which is highly dependent on the US and China, has been directly affected by US-China trade disputes. The purpose of this study was to analyze the effects of US-China trade disputes on the stock price of Korean export firms by performing an event study. This study analyzed stock price fluctuations for 7 days before and after entry into forced [Please check] retaliatory tariffs on Korean exporters' export items subject to retaliatory tariffs. According to the analysis results, among companies that produce goods with major tariffs imposed on China by the US, such as electronic appliances, semiconductors, machinery, and automobiles, those producing electronics and semiconductor products were positively affected by the tariff incident. Secondly, among the companies producing steel, chemicals, and machinery, which the main tariffs imposed by the United States, companies producing steel and chemicals were negatively affected by the incident due to the stagnation of trade between China and the US. The results of this study suggest future trade policy directions for Korea and help to establish an export strategy for major industries.

Study on Power Measurement and Comparison of Marine Current Turbine in a Towing Tank (예인수조를 이용한 조류발전 터빈의 동력 계측 및 비교 연구)

  • Do, In-Rok;Kim, Moon-Chan;Lee, Seung-Ki;Hyun, Beom-Soo
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.14 no.4
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    • pp.230-238
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    • 2011
  • The experimental study for the performances of 100 kW marine current turbines (Horizontal Axis Turbine) has been conducted with three cases of 700 mm diameter model in PNU 100 m towing tank. Three cases of impeller have been designed according to the variation of section configuration and tip shape. The model tests have been carried out at different speed of revolution to find out the scale effect (Reynolds number effect). The designed rake impeller was the best among them in the efficiency point of view especially at high Tip Speed Ratio (TSR). The present study is expected to be extended to conduct at high reynolds number as well as the computational study for the validation.