포화상태에 놓인 C-Type 액체수소 탱크의 슬로싱이 열 유속과 BOG에 미치는 변화의 수치적 분석

이진호,황세윤,이성제,이장현,Lee, Jin-Ho,Hwang, Se-Yun,Lee, Sung-Je,Lee, Jang Hyun 한국전산구조공학회 2022 한국전산구조공학회논문집 Vol.35 No.5

본 논문은 슬로싱 상태에 놓인 포화 상태 액체수소탱크에서 열 유속 및 BOG(Boil-off gas)의 경향을 다루고 있다. 특히, 액체-기체간의 침투 및 혼합에 의한 열 교환에 관심을 두었다. 먼저, VOF(Volume of fluid)와 Eulerian 기반의 다상 유동모델로 모형 슬로싱 실험을 모사하여 압력을 예측하고 계측된 값과 비교하였다. 자유 수면 및 충격 압력 실험 결과와 해석 결과를 비교하였으며, 유체의 속도 예측에서 정확할 수 있음을 간접적으로 증명하였다. 그리고 2차원의 Type-C 원통형 수소탱크를 대상으로 다상열유동해석을 수행하였다. 이때 포화상태에 놓인 액체 및 기체수소를 가정하고, 해석을 통해 각 상간의 혼합에 의한 열 교환의 수준을 확인하고자 하였다. 단, 상간의 열 교환만을 관심으로 두고 있었으므로 질량전달 및 기화모델은 해석에서 제외하였다. 최종적으로 상의 혼합으로 인해 액체수소로 유입되는 열 유속의 기여도에 대하여 정리하였다. 또한 액체수소로 유입되는 열 유속과 집중 질량 기반의 간이식을 통해 BOG 발생량 및 경향을 예측하고 분석하였다. This study was conducted to predict the tendency for heat exchange and boil-off gas (BOG) in a liquefied hydrogen tank under sloshing excitation. First, athe fluid domain excited by sloshing was modeled using a multiphase-thermal flow domain in which liquid hydrogen and hydrogen gas are in the saturated state. Both the the volume of fluid (VOF) and Eulerian-based multi-phase flow methods were applied to validate the accuracy of the pressure prediction. Second, it was indirectly shown that the fluid velocity prediction could be accurate by comparing the free surface and impact pressure from the computational fluid dynamics with those from the experimental results. Thereafter, the heat ingress from the external convective heat flux was reflected on the outer surfaces of the hydrogen tank. Eulerian-based multiphase-heat flow analysis was performed for a two-dimensional Type-C cylindrical hydrogen tank under rotational sloshing motion, and an inflation technique was applied to transform the fluid domain into a computational grid model. The heat exchange and heat flux in the hydrogen liquid-gas mixture were calculated throughout the analysis,, whereas the mass transfer and vaporization models were excluded to account for the pure heat exchange between the liquid and gas in the saturated state. In addition, forced convective heat transfer by sloshing on the inner wall of the tank was not reflected so that the heat exchange in the multiphase flow of liquid and gas could only be considered. Finally, the effect of sloshing on the amount of heat exchange between liquid and gas hydrogen was discussed. Considering the heat ingress into liquid hydrogen according to the presence/absence of a sloshing excitation, the amount of heat flux and BOG were discussed for each filling ratio.

플렉시블 디스플레이

이진호,추혜용,서경수,강광용,Lee, J.H.,Chu, H.Y.,Suh, K.S.,Kang, K.Y. 한국전자통신연구원 2005 전자통신동향분석 Vol.20 No.6

Flexible display는 플라스틱 등 휠 수 있는 기판에 만들어진 평판 디스플레이로, 우수한 표시특성을 그대로 가지면서 접거나 구부리거나 두루마리 형태로 변형이 가능하기 때문에 현재의 평판 디스플레이 시장의 차세대 기술로 평가되어 전세계적으로 급격한 연구가 이루어지고 있다. Flexible display는 원리적으로 종이와 같은 수 센티미터 이내로 휘거나, 구부리거나, 말 수 있는 얇고 유연한 기판을 사용하게 되며, 기존의 딱딱한 유리기판을 사용하는 디스플레이와는 달리 가볍고, 얇고, 내충격성이 강하며, 구부림이 자유롭다. 본 고에서는 flexible display의 핵심 기술, 주요기관의 최근 flexibledisplay 연구 개발동향 및 발전전망 등에 대하여 살펴보기로 한다.

액상환원공정을 이용한 백금 나노 입자의 합성

이진호,김세훈,김진우,이민하,김영도,Lee, Jin-Ho,Kim, Se-Hoon,Kim, Jin-Woo,Lee, Min-Ha,Kim, Young-Do 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.1

In this study, Platinum(Pt) nanoparticles were synthesized by using polyol process which is one of the liquid phase reduction methods. Dihydrogen hexachloroplatinate (IV) hexahydrate $(H_2PtCl_6{\cdot}6H_2O)$, as a precursor, was dissolved in ethylene glycol and silver nitrate ($AgNO_3$) was added as metal salt for shape control of Pt particle. Also, polyvinylpyrrolidone (PVP), as capping agent, was added to reduce the size of particle and to separate the particles. The size of Pt nanoparticles was evaluated particle size analyzer (PSA). The size and morphology of Pt nanoparticles were observed by transmission electron microscopy (TEM) and high resolution TEM (HRTEM). Synthesized Pt nanoparticles were studied with varying time and temperature of polyol process. Pt nanoparticles have been successfully synthesized with controlled sizes in the range 5-10 and 20-40 nm with cube and multiple-cube shapes.

Cardiac Hematoma with Pericardial Effusion in a Dog

이진호,정태호,윤성태,김성현,김민수,박철,Lee, Jin-Ho,Chung, Tae-Ho,Yoon, Sung-Tae,Kim, Seong-hyun,Kim, Min-Su,Park, Chul The Korean Society of Veterinary Clinics 2015 한국임상수의학회지 Vol.7 No.2

A 12-year-old spayed female, Golden Retriever presented with dyspnea and lethargy of 3 months duration. Pericardial effusion and cardiac mass were identified on echocardiography. Pericardiectomy and mass resection were performed for treatment of pericardial effusion and histopathological analysis was conducted for the definitive diagnosis. The mass was diagnosed as hematoma with mainly erythrocyte, fibrin and many of neutrophils based on microscopic description. Severe purulent pericarditis thickened by inflammatory cells and reactive fibrous tissue were identified, but not diagnosed as neoplasm. This is the first case report in veterinary literature of a dog with pericardial effusion caused by cardiac hematoma. 12년령의 중성화한 암컷 골든레트리버가 3개월간의 호흡곤란과 기력저하를 주호소로 내원하였다. 심낭삼출물과 심장부위의 종괴가 심장초음파 상에서 확인되었다. 심낭절제술과 종괴 제거가 이루어졌으며 확진을 위해 조직검사를 수행하였다. 종괴는 현미경 검사 상에서 적혈구와 피브린, 호중구로 이루어진 혈종임이 확인되었다. 염증세포와 반응성 섬유 조직에 의해 두꺼워진 중증의 화농성 심낭염 소견이 확인되었으며, 종양 소견은 관찰되지 않았다. 이 증례는 수의학에서 개의 심장혈종에 의한 심낭삼출물 발생의 최초 보고이다.

플랜트 설비관리 시스템을 위한 효율적인 엔지니어링 데이터관리

이진호,Lee, Jin-Ho 한국플랜트학회 2014 플랜트 저널 Vol.10 No.1

Mn 및 Cr 주강의 주형반응에 관한 연구

이진호,정정연,이종남 ( J . H . Lee J . Y . Jeong,J . N . Lee ) 한국주조공학회 1985 한국주조공학회지 Vol.5 No.4

In order to investigate the mold reaction characteristics of Mn steel and Cr steel castings individually, the mold reaction products were examined by scanning electron microscopy, electron prove microanalyzer and X-ray diffractometer. From this experiment, the results were summarized as follows: 1) The mold reaction depth increased with increase of Mn content, while it decreased with increase of Cr content. 2) Mold reaction depth decreased with Mn content at 1200℃. 3) Mn, among the reaction products, forms a low fusion silicate, MnO·SiO₂while Cr forms a stable oxide, CrO₃which hindering the reaction between FeO and SiO₂thus the formation of FeO·SiO₂was depressed.

개질형 On-Site 수소충전소의 리스크 감소를 위해 요구되는 SIL 등급 달성 방안에 관한 연구

이진호,임재용,Lee, Jin Ho,Lim, Jae-Yong 한국안전학회 2020 한국안전학회지 Vol.35 No.6

In recent years, hydrogen has received much attention as an alternative energy source to fossil fuels. In order to ensure safety from the increasing number of hydrogen refueling stations, prevention methods have been required. In this regard, this study suggested an approach to reduce the risk of hydrogen refueling station by increasing Safety Integrity Level (SIL) for a Steam Methane Reformer (SMR) in On-Site Hydrogen Refueling Station. The worst scenario in the SMR was selected by HAZOP and the required SIL for the worst scenario was identified by LOPA. To verify the required SIL, the PFDavg.(1/RRF) of Safety Instrumented System (SIS) in SMR was calculated by using realistic failure rate data of SIS. Next, several conditions were tested by varying the sensor redundancy and proof test interval reduction and their effects on risk reduction factor were investigated. Consequently, an improved condition, which were the redundancy of two-out-of-three and the proof test interval of twelve months, achieved the tolerable risk resulting in the magnitude of risk reduction factor ten times greater than that of the baseline condition.

균일침전법을 이용항 Hydroxyapatite 분말의 제조 및 가열변화

이진호,박훈,김창은,Lee, Jin-Ho,Park, Hoon,Kim, Chang-Eun 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.1

${CO_3}^{2-}$ containing whisker-like hydroxyapatite powders were synthesized byhomogeneous precipitation method using urea, Dicalcium phosphate anhdrate[DCPA; $CaHPO_4$] and octacalcium phosphate [OCP; $Ca_8H_2(PO_4_)6\cdot5H_20$]were obtained as precursors and they transformed to high crystalline hydroxyapatites at pH 5.62, and 6.54 respectively. According to the condition of the final pH in the solutions for the solution products and urea contents OCP was remained. When the solution product of $Ca^{2-}$ and ${PO_4}^{3-}$ was $1.5\times 10^4$[$mM^2$] and the content of urea was 0.25 mol.$dm^{-3}$ well crystallized whisker-like hydroxyapatite tens of micrometer in length was obtained. By heat treatment DCPA and OCP were decomposed into $\beta$-tricalcium phosphate [$\beta$-TCP ; $\beta$-$Ca_3{PO_4}_2$] and $\beta$-dicalcium phosphate [$\beta$-DCP ;$\beta$-$Ca_2P_2O_4}_2$]. And well-crystallized hydroxyapatite was partially decomposed into $\beta$-TCP at $800^{\circ}C$.

유전 알고리즘을 활용한 완전파형역산 기법의 층상 반무한 지반 전단파 속도 추정

이진호,이세혁,Lee, Jin Ho,Lee, Se Hyeok 한국전산구조공학회 2021 한국전산구조공학회논문집 Vol.34 No.4

전역 최적화 문제의 해를 유전 알고리즘을 사용하여 얻어 완전파형역산을 수행하고 층상 반무한체의 물성치를 추정하는 기법을 제안한다. 조화 수직 하중이 작용하는 층상 반무한체의 동적 응답을 측정하고, 이를 추정 물성치를 사용하여 계산된 응답과 비교한다. 응답의 추정치는 mid-point integrated finite element와 perfectly matched discrete layer를 사용하여 구성된 thin-layer model로부터 얻는다. 전역 최적화 문제의 목적 함수는 응답의 관측치와 추정치의 차이에 대한 L2-norm으로 계산된다. 유전 알고리즘을 사용하여 전역 최적화 문제의 해를 구하여 완전파형역산을 수행한다. 제안된 기법을 기본 진동 모드 뿐만이 아니라 고차 진동 모드도 우세한 다양한 층상 반무한 매질에 적용하여, 측정치가 잡음을 포함하지 않는 경우와 포함하는 경우 모두에 대해서 제안된 완전파형역산 기법은 층상 반무한체의 재료 특성을 추정하는데 적합함을 확인할 수 있다. This paper proposes full waveform inversion (FWI) for estimating the physical properties of a layered half-space. An FWI solution is obtained using a genetic algorithm (GA), which is a well-known global optimization approach. The dynamic responses of a layered half-space subjected to a harmonic vertical disk load are measured and compared with those calculated using the estimated physical properties. The responses are calculated using the thin-layer method, which is accurate and efficient for layered media. Subsequently, a numerical model is constructed for a layered half-space using mid-point integrated finite elements and perfectly matched discrete layers. An objective function of the global optimization problem is defined as the L2-norm of the difference between the observed and estimated responses. A GA is used to minimize the objective function and obtain a solution for the FWI. The accuracy of the proposed approach is applied to various problems involving layered half-spaces. The results verify that the proposed FWI based on a GA is suitable for estimating the material properties of a layered half-space, even when the measured responses include measurement noise.

무요소 계산법의 발전과 전개

이진호,Lee, Jin-Ho 한국수학사학회 2005 Journal for history of mathematics Vol.18 No.4

유한요소법(Finite Element Methods)은 지난 수십 년 동안 다양한 공학문제를 해석하는 주요 수치해석기법으로서, 지속적으로 연구$\cdot$개발되어 오늘에 이르고 있다. 그러나, 유한요소법은 계산을 위하여 요소망을 구성해야 하고 일부의 문제에 대하여서는 요소망을 재구성하는 등 특별한 처리기법과 계산의 소요가 필요하다. 이와같은 단점을 극복하기 위하여 무요소법(Meshfree Methods)이라 불리우는 일단의 수치해석 기법들이 고안되었다. 무요소법은 요소를 사용하지 않고 절점(node)만을 이용하여 함수를 근사하는 수치해석기법이다. 본 논문에서는 무요소법이 고안된 배경과 그 연산구조를 소개하고 무요소법의 대표적인 방법들인 Smoothed Particle Hydrodynamics(SPH)방법, 무요소 갤러킨 방법(Meshfree Galerkin Methods) 그리고 무요소 선점법(Meshfree Point Collocation Methods)의 기본 개념과 이들 수치해석기법의 방법론을 알아본다. 그리고 이들 방법의 장단점과 그 적용 예를 통하여 무요소 계산법의 유효함을 보인다. Finite element Methods(FEM) have been the primary computational methodologies in science and engineering computations for more than half centuries. One of the main limitations of the finite element approximations is that they need mesh which is an artificial constraint, and they need remeshing to solve in some special problems. The advantages in meshfree Methods is to develop meshfree interpolant schemes that only depends on particles, so they relieve the burden of remeshing and successive mesh generation. In this paper we describe the development of meshfree particle Methods and introduce the numerical schemes for Smoothed Particle hydrodynamics, meshfree Galerkin Methods and meshfree point collocation mehtods. We discusse the advantages and the shortcomings of these Methods, also we verify the applicability and efficiency of Meshfree Particle Methods.