• 대한조선학회논문집
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• 제57권2호
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• pp.88-95
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• 2020

There have been many attempts to predict resistance of vessels in ice floe environment, but they mostly have both strong and weak points at the same time; for instance, simplified formulas are very fast but less flexible to types of ship and ice conditions and other numerical techniques need high computing cost for increased accuracy. A new numerical simulation technique of combining explicit finite element analysis code with a user-subroutine to control real-time forces acting on ice floes was proposed, thereby it was possible to predict ship-to-ice floe resistance with higher convenience and accuracy than other proposed approaches. The basic theory on how real-time hydrostatic and hydrodynamic forces acting on ice floes could be generated using user-subroutine was explained. The heave motion of a single ice floe was simulated using the user-subroutine and the motion amplitudes and periods were almost consistent with analytic values. Towing tests of an icebreaker model ship were simulated using explicit finite element analyses with the user-subroutine. The ice-induced resistance obtained from the towing experiments and simulations showed significant differences. Intentional increase of the drag coefficient to increase the contact duration between the ice floes and rigid model ship leaded the total resistance to be substantially consistent between the model tests and numerical simulations.

• 한국항공우주학회지
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• 제46권11호
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• pp.892-901
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• 2018

본 연구에서는 극초음속 비행체의 공력/열/탄성학적 거동을 반영할 수 있는 효율적인 공력 열하중 요소를 개발하였다. 빈번하게 설계 변경이 이루어지는 초기 설계 단계에서 효율적으로 사용될 수 있도록 준 해석적인 관계식을 적용하여 공력 하중과 열 하중을 구조 변형의 함수로 기술하고, 이를 기반으로 공력 열하중 요소를 정식화하였다. 정식화된 요소는 상용 프로그램의 사용자 서브루틴 형태로 구현하였으며, 이를 이용하여 극초음속 비행체 조종면의 공력/열/탄성학적 유한요소 연계해석을 수행하고 그 유용성을 확인하였다.

• 디지털콘텐츠학회 논문지
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• 제13권3호
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• pp.431-438
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• 2012

현재 국내에는 스마트폰 시장의 성장으로 인해, 많은 모바일 어플리케이션들이 개발되어 출시되고 있다. 그러나 현재까지 모바일 어플리케이션의 사용자들이 무엇에 대해 관심이 많은지에 관한 연구는 부족한 실정이다. 이를 위해 본 연구에서는 기존 스마트폰의 수용 원인에 관한 연구들과 어플리케이션의 수용 요인에 관한 연구들에서 사용된 요인들을 모바일 어플리케이션에 적합하게 변경하여 모바일 어플리케이션의 관심 요소로 설정한다. 그리고 안드로이드 마켓의 상위 20개의 유료 어플리케이션들에 관한 리뷰들을 모바일 어플리케이션의 관심 요소로 코드화하여 어떠한 요소들이 모바일 어플리케이션의 사용자들의 관심을 유도하는지를 분석하고, 분석된 요소를 중심으로 개발 방법을 제시한다. 본 논문은 성공적인 모바일 어플리케이션을 개발하여 출시하려는 개발업체들에게 유익한 정보를 제공할 수 있을 것이다.

• 디지털융복합연구
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• 제17권11호
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• pp.517-522
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• 2019

많은 비즈니스에서 챗봇은 사용자의 질문에 가장 즉각적이고 직접적인 피드백으로 제공함으로써 사용자 경험을 높여가고 있으며 그 활용 영역이 커져가고 있다. 본 연구에서는 챗봇의 정의를 비롯해 명령방식, 기능, 플랫폼에 따른 세 가지 유형을 구분되는 요소에 따라 분류해 보았다. 그 과정에서 기능적 구분 요소는 패턴인식, 자연어처리, 시멘틱 웹, 텍스트 마이닝, 상황인식 컴퓨팅의 기능적 부분의 핵심 기술 요소가 챗봇 UX를 위해 필요하지만 현재 단계에서의 한계도 알 수 있었다. 이를 바탕으로 더 나은 사용자 경험을 위한 챗봇의 UX요소를 페이스북, 스카이프, 텔레그램, 구글어이스턴트를 대상으로 분석하였으며 카드와 같은 기본 UI요소와 빠른 응답, 명령, 영구 메뉴의 적용이 사용자 경험요소로 필요함을 알 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권10호
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• pp.4759-4780
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• 2017

Full Dimension multiple input multiple output (FD-MIMO) architecture employs a planar array design at the Base Station (BS) to provide high order multi-user MIMO (MU-MIMO) via simultaneous data transmission to large number of users. With FD-MIMO, the BS can also adjust the beam direction in both elevation and azimuth direction to concentrate the energy on the user of interests while minimizing the interference leakage to co-scheduled users in the same cell or users in the neighboring cells. In a typical highly populated macrocell environment, modelling the elevation angular characteristics of three-dimensional (3D) channel is critical to understanding the performance limits of the FD-MIMO system. In this paper, we study the throughput performance of FD-MIMO system with varying elevation angular spread and inter-element spacing using a 3D spatial channel model. Our results show that for a typical urban scenario, horizontal beamforming with correlated antenna spacing achieves optimal performance but by restricting the spread of elevation angles of departure, elevation beamforming achieves high array gain with wide inter-element spacing. We also realize significant gains due to spatial array processing via modelling the elevation domain and varying the inter-element spacing for both the transmitter and receiver.

• 한국기계가공학회지
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• 제14권2호
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• pp.121-126
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• 2015

In this research, a tool was developed for the rapid performance of three-dimensional finite element analysis (3D FEA) of a machine tool spindle system made of a shaft and bearings. It runs the FEA with data, such as the bearing stiffness and the coordinates of the points, to define the section of the shaft, bearing positions, and cutting point. developed for the spindle system and then implemented with the tool using an object-oriented programing technique that allows the use of the objects of the CAD system used in this research. Graphic user interfaces were designed for a user to interact with the tool. It provides rapid evaluation of the design of a spindle system, and therefore, it would be helpful to identify a near optimal design of a spindle system based on, say, static stiffness with design changes and, consequently, FEA.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.635-640
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• 2010

When using finite element pogram ABAQUS to compute material characteristics, one builds a user material subroutine if unique constitutive feature needs to be included. In ABAQUS/Standard, UMAT subroutine should be built, and in ABAQUS/Explicit, VUMAT should be used. Although two subroutines carry out the same type of task, two different programs should be made depending on the working environment, and it is not easy to program the subroutines following the manual without enough understanding of solid mechanics. In this paper, difference between UMAT and VUMAT subroutines is epitomized, and a conversion scheme from UMAT to VUMAT is discussed. An example shows that the two programs give the same stress computation result.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.193-198
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• 2021

The application of e-Voting plays an important role in order to support democracy activities in Indonesia, such as elections at different levels. E-Voting has the function of providing better service to people in order to participate in elections. This research attempts to develop the appearance of the user interface of e-Voting based on users' emotional preferences using Kansei Engineering. Kansei Engineering is used in this research to analyze emotional feelings regarding e-Voting applications' presented Kansei words and give a recommendation on the most suitable user interface to be considered in their development. This research observed two main users' emotional feelings ("calm" and "formal") selected from ten Kansei words. The final recommendation is a conceptual element designed for designing e-Voting applications based on the Kansei word "calm".

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 봄 학술발표회 논문집
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• pp.25-32
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• 1994

The pre-processor for finite to element structural analysis considering the user-friendly device is developed by using GUI. This can be used on WINDOWS' environment which is realized the multi-tasking and the concurrency by object-oriented paradigm. Data input can be done easily through menu, dialog box, automatic stepwise input and concurrent representation with the structural geometry on multiple windows. It in designed to control integratedly the pre-processing, execution and the post-processing of the finite element structural analysis program on multiple windows, and input data can be seen with result outputs at the same time. In addition, the object-oriented programming environment makes convenient revision and addition of the program components for expanding the scope of analysis and making better user environment.

• 한국생산제조학회지
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• 제24권2호
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• pp.166-171
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• 2015

In this study, an automation tool was developed for rapid evaluation of machine tool spindle designs with automated three-dimensional finite element analysis (3D FEA) using solid elements. The tool performs FEA with the minimum data of point coordinates to define the section of the spindle shaft and bearing positions. Using object-oriented programming techniques, the tool was implemented in the programming environment of a CAD system to make use of its objects. Its modules were constructed with the objects to generate the geometric model and then to convert it into the FE model of 3D solid elements at the workbenches of the CAD system using the point data. Graphic user interfaces were developed to allow users to interact with the tool. This tool is helpful for identification of a near optimal design of the spindle based on, for example, stiffness with multiple design changes and then FEAs.