• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.34-44
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• 1996

In order to examine the accuracy of the intensity method, the fiber orientation-angle distribution of fiber-reinforced polymeric composites is measured using image processing. The fiber orientation function is calculated from the fiber orientation measured by the soft X-ray photograph. Theoretical and experimental results of fiber orientation function are compared for the composites with different fiber contents and fiber orientations. The intensity method is used for the experimental investigation and the measured fiber orientation function is compared to the calculated one. The relations between the measured and the simulated fiber orientation functions $J{\small{M}}$ and $J{\small{S}}$ respectively are identified. For the fiber length of 1.000mm and 2.000mm, it shows that $J{\small{M}}=0.83J{\small{M}}$. However. in general. the value of $J{\small{M}}$ decreases as the fiber length increases. For GFRP composites the relations between $J{\small{M}}$ and theoretical value J show that $J{\small{M}}$=0.73J for short fiber and $J{\small{M}}$=0.81J for long fiber.

• Tribology and Lubricants
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• v.31 no.4
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• pp.163-169
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• 2015

This paper describes a design method for the corner radius of a contacting body using the theoretical approach of contact mechanics. A complete contact, as in the case of a sharp-cornered punch, produces singular contact traction: whereas, in an incomplete contact, the singular contact traction disappears because of the rounded corners, and the contact edges are within the rounded regions. The design method aims to determine the conditions of the contact force as well as the material properties in an incomplete contact. The incomplete contact changes into the complete contact again when the contact edges exceed the rounded regions owing to either an increased contact force or the compliance of the materials. The contact length of a rounded punch is used as a parameter to derive the required conditions. As a result, a design formula is obtained, which provides a minimum allowable radius when the materials, normal contact force, and the length of a flat region of the punch are predetermined. This work consists of two parts: Part I includes a theoretical background, design method, and formula, and Part II describes the actual process with the investigation of design parameters.

• Journal of the Society of Naval Architects of Korea
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• v.30 no.1
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• pp.30-44
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• 1993

This paper deals with both experimental and theoretical methods for performance prediction of asymmetric stater propulsion systems which have been used for the purpose of recovery of a propeller slipstream rotational energy due to a stator located in front of the propeller. Using the developed computer code based on the lifting surface theory, theortical investigation on the interaction between the stator and the propeller is provided in order to obtain general insight on the performance characteristics of the propulsion systems in uniform and non-uniform flow. Such theoretical calculations have end agreements with model Inset results. The asymmetric stator would give an efficiency gain of about 6% to the compound propulsor system compared with the single propeller system.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.4
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• pp.39-45
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• 1982

A floating rig, which has been used to develop the ocean resources has a common characteristics with the catamaran ship that it is composed of the two simple hulls. So the motion responses of the floating rig can be predicted theoretically with the aid of the strip method as those of the catamaran. And for the strip method, the two-dimensional hydrodynamic coefficients are the most important inputs to predict the results accurately. In this report, a theoretical method is proposed for calculating two-dimensional hydrodynamic forces and moments acting upon arbitrary shaped twin-hull cylinders, which are forced to make a heaving, swaying and rolling oscillation about their mean position on the free surface of a finite depth water. The theoretical results by making use of the singularity distribution method are presented. The accuracy of the coefficients was confirmed to be reasonable by the comparison with the Ohkusu's results for two circular cylinders in an infinite depth water. The depth effects on two-dimensional hydrodynamic coefficients for two circular cylinders are also checked. In some range of wave numbers, large differences in the behavior of hydrodynamic coefficients between for a finite depth and for an infinite depth are shown.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.169-174
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• 2003

We report theoretical and experimental investigation of a polarizer made of single mode side-polished fiber covered with a metal film. The influence of the metal film thickness and the refractive index of overlay on the device performance has been analyzed in terms of the normal mode theory. Based on the theoretical prediction, a polarizer with 40 ㏈ of polarization extinction ratio and 0.5 ㏈ insertion loss at optical communication wavelength has been realized.

• Magazine of the Korea Concrete Institute
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• v.3 no.3
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• pp.129-139
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• 1991

The mechanical hehavior of relIlforced concrete beams with steel fibers is investigated 111 the present study. An expenmental program was set up and several series of rem forced concrete beams have been tested, including two senes of singly-reinforced concrete beams and one senes of doubly-reinforced concrete beams. It was found from th, :se measurements that the crack widths lIlcrease almost llIlearly With the lIlcrease of steel stress and that the crack Widths at the same loadlJ1g stages are greatly reduced as the contents of steel fibers increase. The present study also IJ1chcates that the ductiiIty and the ultJmate resistance are remarkably enhanced due to the addition of steel fibers. A theoretical mex1e1 for the flexural analysis of fiber-reinforced concrete beam which takes into account the effects of fibers JS also proposed.

• Advances in nano research
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• v.1 no.3
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• pp.133-151
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• 2013

The availability of advanced nanotechnological methodologies (experimental and theoretical) has widened the investigation of biological/organic matter in interaction with substrates. Minerals are good candidates as substrates because they may present a wide variety of physico-chemical properties and surface nanostructures that can be used to actively condense and manipulate the biomolecules. Scanning Probe Microscopy (SPM) is one of the best suited techniques used to investigate at a single molecule level the surface interactions. In addition, the recent availability of high performance computing has increased the possibility to study quantum mechanically the interaction phenomena extending the number of atoms involved in the simulation. In the present paper, firstly we will briefly introduce new SPM technological developments and applications to investigate mineral surfaces and mineral-biomolecule interaction, then we will present results on the specific RNA-mineral interaction and recent basics and applicative achievements in the field of the interactions between other fundamental biological molecules and mineral surfaces from both an experimental and theoretical point of view.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.12
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• pp.965-970
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• 2016

Fuel used in the steel metallurgy industry is stored in huge stage systems called SILO. Fuel is released by RDM (Rotary Discharge Machine), at the place of utilization. RDM is located in the Silo, and is constituted of a main frame, driving part, discharging part and control part. RDM is combined to a direct motion on the rail in tunnel, having a rotary motion enabled by a motor. In this paper, we calculate the theoretical discharging capacity of RDM to confirm the correlation between design element and discharging capacity of RDM. Also, through structure analysis, we confirm the vulnerable point of RDM when it discharges the storage materials. We hope to apply these results to design a more efficient RDM.

• International Journal of Quality Innovation
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• v.7 no.2
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• pp.69-82
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• 2006

Organisations worldwide strive to develop their management systems for business functions, ranging from quality and environment to safety, information security and social responsibility. During the latest decade a considerable amount of these efforts has been concentrated on introducing and applying standards such as the ISO 9001 and ISO 14001. The need for Integrated Management Systems (IMS) often arises as a result of decisions to implement Environmental Management System (EMS) and/or an occupational health and safety management system in addition to a Quality Management System (QMS). At the end of 2003, approximately 3200 organisations in Sweden had an ISO 9001 certificate, and approximately 3400 organisations had a certificate based on an EMS. Dealing with separate management systems and ensuring that they align with the organisation's strategies and goals, has proved difficult. Owing to the large number of organisations certified according to multiple types of systems, an increasing number of organisations are establishing IMS. There are examples of companies, which chose to integrate EMS and QMS into a co-ordinated implementation approach, and although sparse, the research within this area indicates potential benefits of using an integrated approach. This paper presents both a theoretical and an empirical investigation with the aim to elucidate problems related to the integration of management systems. Furthermore, the paper will present recommendations for succeeding in such integrations and, hence, contributing to an increased understanding on how IMSs should be designed and implemented.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.889-896
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• 2020

The vertically inverted U-tube steam generator (UTSG) is widely used in the pressurized water reactor (PWR). The reverse flow behavior generally exists in some U-tubes of a steam generator (SG) under both single- and two-phase natural circulations (NCs). The behavior increases the flow resistance in the primary loop and reduces the heat transfer in the SG. As a consequence, the NC ability as well as the inherent safety of nuclear reactors is faced with severe challenges. The theoretical models for calculating single- and two-phase flow pressure drops in U-tubes are developed and validated in this paper. The two-phase reverse flow characteristics in two types of SGs are investigated base on the theoretical models, and the effects of the U-tube height, bending radius, inlet steam quality and primary side pressure on the behavior are analyzed. The conclusions may provide some promising references for SG optimization to reduce the disadvantageous behavior. It is also of significance to improve the NC ability and ensure the PWR safety during some accidents.