구장입자의 현탁액에 관한 유동변형론

이기준,Sather,N F 한국화학공학회 1971 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.9 No.4

This paper presents a statistical mechanical description of the random motion of particles in suspension and some results derived there-from for the viscosity of concentrated suspensions of solid spherical particles. In statistical mechanics the information about the probability of dynamical states of the particles of a fluid (i. e., their positions, translational velocities and rotational velocities) is embedded in a particle distribution function, and all of the macroscopic properties of the fluid are specified as integral moments of the distribution function. In particular, the local stress in a suspension is defined as the integral over all particle states of the distribution weighted with the stress at a point for a given instantaneous total particle state. Thus, the calculation of the rheological properties of the suspension comes down to a determination of the distribution function and this local stress function. If the overall shear rate in the suspension is steady and not too large and the particles are neutrally buoyant solid spheres, the net forces and torques on the particles are zero and the local fluid motion is governed by the Stokes equations. It is shown that under these conditions 1) the particle distribution function is independent of the linear and angular velocities of the particles and so is uniquely determined by the particle positions, 2) the viscosity of the suspension must be independent of the shear rate for all concentrations, and 3) the viscosity can be written in a power series in the concentration of particles in which the term of the nth power is the incremental contribution to the viscosity from interactions involving particles. In order to calculate the coefficients of these terms the fluid velocity near the surface of a sphere moving with its neighbors in a, shear field is required. Since an exact determination of the flow field is impractical to obtain for groups of more than two particles, an approximate solution of the Stokes equations obtained by the method of weighted residuals is used in the calculations of the suspension viscosity reported here. The particle configuration is assumed to be simple cubic, and the distribution of interparticle distances is obtained from an approximate statistical model. The viscosity-concentration relationship calculated under these assumptions is found to agree closely with the compilations of experimental data reported by Rutgers and Thomas.

EPB-TBM 암반굴착시 스크류컨베이어의배토 거동에 대한 DEM 기반 수치해석적 연구

이기준,권태혁,김훈태 사단법인 한국터널지하공간학회 2019 한국터널지하공간학회논문집 Vol.21 No.1

Tunnel construction by TBMs should be supported by the performance of a screw conveyor in order to obtain the optimum penetration rate, so studies related to the screw conveyor performance have been being conducted. Compared to the study on the performance of the screw conveyor for the soil, however, the research on the performance of the screw conveyor for the rock is insufficient. Considering the domestic tunnel sites with more rock layers than soil layers, simulation of discharge of 6 types of rock chips by the screw conveyor was conducted using DEM. Regardless of the shape and volume of the rock chips, the discharge rates of the rock chips by the parallel placed screw conveyor at a speed of 10 RPM in the same rock mass were about 20% (standard deviation: 1.3%) of the maximum volume of discharge rate by the screw conveyor. It is expected that this study can be used as a reference material for screw conveyor design and operation in TBM excavations in rock masses. 'TBM 터널공사 시 스크류컨베이어의 배토 거동에 대한 이해는 굴진율 향상을 위한 중요한 요소이다. 본 연구에서는 지반에서 디스크 커터에 의해 생성되는 암반칩의 형상에따라 스크류컨베이어 내부에서의 이동 및 배토 거동에 대한 연구를 수행하였다. 입자기반의 DEM 수치해석기법을 이용하여, 6가지의 대표적인 모양에 대한 암반칩을 클러스터로 형성하였다. 또한, 실제 스크류컨베이어의 3D 축소모델을 형성한 후, 다른 모양의 암반칩의 시간당 배토량을 측정하였다. 시뮬레이션 결과, 스크류컨베이어의 경사각이 0°일 때, 동일한 암반에서 암반칩의 형상과 부피와 상관없이 10 RPM 속도에서의 스크류컨베이어 배토량은 스크류컨베이어 최대 배토량의 약 20%로 나타났다(표준편차: 1.3%). 본 연구 결과는 암반용 TBM 설계 및 암반에서의 TBM 굴착 시 스크류컨베이어 운용에 참고할 수 있는 자료로 사용될 수 있을것으로 예상된다.

A Newly Developed State-of-the-Art Full-Scale Excavation Testing Apparatus for Tunnel Boring Machine (TBM)

이기준,류희환,권태혁,조계춘,김경열,홍성윤 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.12

Construction of urban tunnels using a tunnel boring machine (TBM) is often favored over drilling-and-blasting based excavation method. Often, TBMs are customized and re-used in fields. However, little effort has been made to verify the status quo of the reused TBM prior to its placement, and no apparatus or method is available to examine the excavation performance of whole, assembled TBMs. Therefore, we present a newly developed apparatus which can examine the excavation performance of small cross-section TBMs with the cutterhead diameter of ~3.5 m at full scale. The equipment was verified with a rock-like concrete specimen, in which the excavation of TBM was examined while varying the thrust and cutterhead rotational speed. The test results reveal the positive impact of thrust on the penetration rate (PR) and penetration depth (Pe), as well as a linear relationship between PRand the cutterhead speed. This proves that the presented full-scale TBM excavation testing method is capable to produce reliable and remarkably consistent results. The presented full-scale excavation testing method can be used to examine the functionality of a TBM of interest and further explore the effect of different ground conditions, such as rock strength, joints, and weathering, and the effect of different cutterhead design, including the number of cutters, cutter shape, and cutter location.

Additive anti-inflammation by a combination of conjugated linoleic acid and a-lipoic acid through molecular interaction between both compounds

이기준,고윤주,강상기,김휘수,조종수,최윤재 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.3

Alpha lipoic acid (LA) and conjugated linoleic acid (CLA) have been well-documented on a variety of functional effects in health foods. The main purpose of this study was focused on the additive anti-inflammatory activity of the combination of LA and CLA in vitro. Raw 264.7 cells induced by lipopolysaccharide were treated with LA and CLA individually or in combination at a variety of concentration ranges. Co-treating 25 lM of LA and 25 lM of CLA significantly inhibited pro-inflammatory cytokines compared to the same concentration of single LA- or CLA-treated group. The molecular mechanism of anti-inflammation by a combination of these compounds was attributed to extracellular signal-regulated kinase-1 (ERK1) and peroxisome proliferator-activated receptor gamma (PPARc). Also, the molecular interaction between both compounds was confirmed by NMR. Our findings suggested that the combination of CLA and LA showed potential additive effect on anti-inflammation through the molecular interaction of both compounds.

IndoorGML을 활용한 실내공간 멀티미디어 위치 인코딩 방법

이기준 대한공간정보학회 2013 Spatial Information Research Vol.21 No.4

Most multimedia contains location information whether they are implicit or explicitly, and which are very useful for several purposes. In particular, we may use location information in defining query conditions to retrieve relevant multimedia. For this reason, a number of works have been done to organize and retrieve geo-referenced multimedia data. However, they mostly focus on outdoor space where position is identified by (x, y, z) coordinates. In this paper, we focus on multimedia in an alternative space, indoor space, which differs from outdoor space in several aspects. First indoor space is considered as symbolic space, where location is identified by a symbolic code such as room number rather than coordinates. Second, topological information is a crucial element in providing indoor spatial information services. Third, indoor space is in more micro-scale than outdoor space, which influences on determining the visibility of cameras. Based on these different characteristics of indoor space, we survey the requirements of management systems of indoor geo-referenced multimedia. Then we propose a geo-coding scheme for multimedia in indoor space as an extension of IndoorGML, an OGC(Open Geospatial Consortium) candidate standard for indoor spatial information. We also present a prototype system called, IngC (INdoor Geo-Coding) developed to store and manage indoor geo-referenced multimedia. 대부분의 멀티미디어 데이터는 위치정보를 가지고 있다. 따라서 각 멀티미디어 데이터에 적절한 위치정보를 추가하면, 다양한 용도로 활용이 가능하다. 특히 멀티미디어의 위치검색이 다양한 검색조건으로 제공될 수 있다. 지금까지 멀티미디어의 위치는 주로 실외공간의 (x, y, z) 좌표공간을 기반으로 정의된다. 최근 실내공간 정보기술이 발달하면서 실외뿐 아니라, 실내공간에서도 다양한 위치기반 서비스가 가능하며, 멀티미디어의 실내공간 안에서의 위치를 정의할 수 있게 되었다. 그러나 실내공간의 위치는 실외공간의 위치참조체계와 다르다. 예를 들어, 실내공간에서 위치를 지정할 때는 좌표를 이용하지 않고, 층과 방의 번호를 이용한다. 방 번호와 같은 기호를 이용하여 위치를 지정하는 공간을 기호공간이라고 한다. 본 논문에서는 기호공간을 기반으로 실내공간에서 만들어진 멀티미디어 자료의 위치를 지정하는 방법을 제안한다. 이 방법은 특히 현재 진행 중인 OGC의 실내공간정보 표준인 IndoorGML에서 제시하는 데이터모델을 이용한다. 따라서 본 방법은 실내공간에서 만들어진 멀티미디어의 위치를 효과적으로 표현하며, 동시에 여러 시스템이나 서비스간의 호환성을 높이는데 유용하다.

비압축성 점성유의 칼렌더 공정에 대한 유변학적 해석(1)

이기준,이재욱 한국화학공학회 1980 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.18 No.4

高分子加工等의 工程에서 흔히 볼 수 있는 非뉴톤性 流體의 流動現象을 해석하기 위한 연구의 一環으로서 power-law 모델로의 적용이 가능한 경질 PVC용융체를 대상물질로 하여 半徑 및 回轉速度가 서로 다른 非對稱型 칼렌더에서의 非뉴톤性 流體의 速度, 壓力, 剪斷應力場의 변화를, 정확한 경계조건을 설정할 수 있는 Bipolar cylindrical 좌표계를 도입하고 lubrication approximation을 적용하여 이론적으로 관찰하였다. 半徑比 및 回轉速度比에 따라 速度場과 壓力場은 현저하게 변화를 나타냈으며 회전속도비가 반경비보다 流醴의 流動現象에 더욱 중요한 영향을 미치는 인자임을 알았다. 이와 아울러 필름의 생성두께와 半徑比, 회전속도 比에 따른 운전인자, 즉 유량, 소요동력 등의 변화를 조사함으로써 칼렌더의 설계 및 최적운전조건에 관한 자료를 제시할 수 있었다. Non-Newtonian fluid flow between a pair of rotating cylinders with non-equal size rolls and/or non-equal speed of the rolls is studied theoretically for the power-law fluids at the isothermal condition, using the bipolar cylindrical coordinates which could satisfy the exact boundary conditions. A theoretical analysis of the velocity, pressure and shear stress distributions in the flow field is given by solving equations of continuity and motion applying the lubrication approximation. The processing parameters such as volumetric flow rate and total power required to drive the rolls are calculated and presented in terms of the geometrical and kinematical parameters of the asymmetric calendering systems.

궤양성 대장염과 동반된 자가면역 간염 1예

이기준,이준성,배원기,김남훈,김경아,문영수,주미 대한내과학회 2011 대한내과학회지 Vol.80 No.-

Autoimmune hepatitis (AIH), primary sclerosing cholangitis (PSC), and primary biliary cirrhosis (PBC) are the major immune-mediated chronic liver diseases. They are characterized by circulating autoantibodies, hypergammaglobulinemia, unique clinical features, and associations with other autoimmune diseases, such as inflammatory bowel disease and autoimmune thyroiditis. Primary biliary cirrhosis is known to be associated with inflammatory bowel disease, such as ulcerative colitis. On the other hand, autoimmune hepatitis is rarely associated with ulcerative colitis. Here, we report a case diagnosed as autoimmune hepatitis combined with ulcerative colitis on the basis of histological and endoscopic findings. (Korean J Med 2011;80:S106-S110) 원발경화담관염 환자에서 궤양성 대장염 동반되는 보고는 있으나 자가면역간염 단독으로 궤양성 대장염이 동반되어 발생하는 경우는 국내에서 보고된 바가 없다. 이에 저자들은 자가면역 간염 환자에게서 궤양성 대장염이 동반되어 치료한 경우를 경험하였기에 이를 보고하는 바이다.

' 80년도 춘이총회 연구발표 논문초록 : A - 2 비압축성 점성유의 칼렌더 공정에 대한 유변학적 해석

이기준,이재욱 한국화학공학회 1980 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.18 No.3

도로네트워크 기반 이동 객체들 간의 배타적 최근접 쌍 모니터링 방법

이기준,권오제,백윤선,Li, Ki-Joune,Kwon, O-Je,Baek, Yun-Sun 한국공간정보학회 2009 한국공간정보학회지 Vol.17 No.2

Finding exclusive closest pairs in road network is very useful to real applications such as, for example, finding a closest pair between a passenger and a nearby taxi in a road network. Few studies, however, have been interested in this problem. To match two close moving objects exclusively, one object must belong to only one result pair. Because moving objects in a road network change their position continuously, it is necessary to monitor closest pair results. In this paper, we propose a methodology to monitor k exclusive closest pairs via a road network. Proposed method only updates the results which are influenced by objects' movement. We evaluated the performance of the proposed method with various real road network data. The results show that our method produces better accuracy than normal batch processing methods. 배타적 최근접 쌍 검색 방법은 가까이 있는 승객과 택시 간에 쌍을 맺어주는 것과 같은 실 생활 응용 분야에 유용하게 쓰일 수 있으나, 그 중요성에 비해 많은 연구가 진행되지 않았다. 두 이동 객체가 배타적으로 최근접 쌍이 되기 위해서는 객체는 반드시 하나의 결과 쌍에 속해야 한다. 하지만, 이동 객체는 위치가 빈번하게 변하기 때문에 초기의 배타적 최근접 쌍 결과를 모니터링 해 줄 필요가 있다. 본 논문에서는 도로 네트워크를 기반으로 k 개의 배타적 최근접 쌍을 구하고 그 결과를 모니터링 하기 위한 방법을 제안한다. 제안하는 방법은 모든 객체에 대해 배타적 최근접 쌍 검색을 재수행하지 않고, 결과가 갱신되는 범위를 제한하여 부분적인 재수행을 함으로써 모니터링 수행 시간을 줄였다. 다양한 실제 도로 네트워크를 이용한 실험들을 통해 본 논문에서 제안하는 모니터링 방법의 성능을 측정하였다. 실험 결과는 본 논문에서 제안하는 모니터링 방법의 정확도가 일반적인 일괄처리 방법들에 비해 뛰어남을 보인다.

앗, 이것도 발효식품

이기준,이근하 전주국제발효식품엑스포 조직위원회 2006 발효 : 맛있는 잡지 Vol.2 No.2