• Nuclear Engineering and Technology
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• 제53권11호
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• pp.3543-3562
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• 2021

The methods and performance of a 3D pin-by-pin neutronics code based on the 2D/1D decoupling method are presented. The code was newly developed as an effort to achieve enhanced accuracy and high calculation performance that are sufficient for the use in practical nuclear design analyses. From the 3D diffusion-based finite difference method (FDM) formulation, decoupled planar formulations are established by treating pre-determined axial leakage as a source term. The decoupled axial problems are formulated with the radial leakage source term. To accelerate the pin-by-pin calculation, the two-level coarse mesh finite difference (CMFD) formulation, which consists of the multigroup node-wise CMFD and the two-group assembly-wise CMFD is implemented. To enhance the accuracy, both the discontinuity factor method and the super-homogenization (SPH) factor method are examined for pin-wise cross-section homogenization. The parallelization is achieved with the OpenMP package. The accuracy and performance of the pin-by-pin calculations are assessed with the VERA and APR1400 benchmark problems. It is demonstrated that pin-by-pin 2D/1D alternating calculations within the two-level 3D CMFD framework yield accurate solutions in about 30 s for the typical commercial core problems, on a parallel platform employing 32 threads.

• Journal of Power Electronics
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• 제19권4호
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• pp.980-988
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• 2019

When compared with traditional power frequency generators, the frequency of a super high-speed permanent magnet generator (SHSPMG) is a lot higher. In order to study the influence of frequency on the electromagnetic field of SHSPMGs, a 60000rpm, 117kW SHSPMG was taken as a research object. The two-dimensional finite element model of the generator was established, and the two-dimensional transient field of the generator was simulated. In addition, a test platform of the generator was set up and tested. The reliability of the simulation was verified by comparing the experiment data with that of the simulation. Then the generator electromagnetic field under different frequencies was studied, and the influence mechanism of frequency on the generator electromagnetic field was revealed. The generator loss, voltage regulation rate, torque and torque ripple were analyzed under the rated active power load and different frequencies. The influences of frequency on the eddy current density, loss, voltage regulation rate and torque ripple of the generator were obtained. These conclusions can provide some reference for the design and optimization of SHSPMGs.

• 패션비즈니스
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• 제25권5호
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• pp.88-98
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• 2021

In this study, the characteristics of digital anthropometric methods were determined with case studies. These methods were broadly classified into two categories: non-wearable and wearable. Then, these categories were further classified into four types: 3D Scanning, mobile app, smart clothing, and smart tool Among the non-wearable types, the "3D scanning" technique was based on the use of 3D hardware equipment. With this technique, the body shape was measured and the internal body information was obtained. Therefore, it is used in fields of healthcare and fitness. Among the wearable types, "Smart clothing" involves a special clothing that measures human body and a smartphone application. Both the components are linked to a fashion platform, which is based on the measured sizes that help shoppers. The "Smart tool" has the characteristic of measuring only with smart tools and smartphone applications; it does not involve the measurement of images. The common advantage of digital anthropometric methods are as follows: they reduce the time and cost of measurement by enabling self-measurement. Moreover, simple measurements are used to determine the size of anthropometry. Thereafter, it accumulates this data to track the continuous changes in size. From an industrial point of view, digital anthropometric technology should be used to increase sales. The on-demand market can be expanded as global consumers would throng the Korean fashion market. For the consumer, an avatar should be created to fit the user's size. This would provide a fun experience to the user.

• 융합경영연구
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• 제11권1호
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• pp.21-30
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• 2023

Purpose: As one of the ongoing studies on the distribution industry, the purpose of this study is to identify the research trends on online shopping so far to propose not only the development of online shopping companies but also the possibility of coexistence between online and offline retailers and the development of the distribution industry. Research design, data and methodology: In this study, the English abstracts of 645 papers on online shopping registered in scienceON were obtained. For the analysis through BERTopic and LDA using Python 3.7 and identifying which topics were interesting to researchers. Results: As a result of word frequency analysis and co-occurrence analysis, it was found that studies related to online shopping were frequently conducted on factors such as products, services, and shopping malls. As a result of BERTopic, five topics such as 'service quality' and 'sales strategy' were derived, and as a result of LDA, three topics including 'purchase experience' were derived. It was confirmed that 'Customer Recommendation' and 'Fashion Mall' showed relatively high interest, and 'Sales Strategy' showed relatively low interest. Conclusions: It was suggested that more diverse studies related to the online shopping mall platform, sales content, and usage influencing factors are needed to develop the online shopping industry.

• 대한치과보철학회지
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• 제48권4호
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• pp.266-272
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• 2010

연구 목적: 임플란트 경부 역사면의 디자인이 변연골 응력분포에 미치는 영향을 알아보기 위해 유한요소법을 사용하여 비교분석하였다. 연구 재료 및 방법:경부 직경 5.5 mm, 길이 8 mm의 매립형 (submerged type) 고정체 (Dentis Co., Daegu, Korea)를 연구모델로 선정하였다. 임플란트 경부 역사면의 디자인을 높이 (h, 0.4 mm, 1.0 mm)와폭경({5.5 - (3.34 + 2b)} / 2, [b, 0.2 mm, 0.3 mm, 0.4 mm])을 다르게 하여 총 여섯 가지의 실험 임플란트 조합으로 구분하였다. 축대칭 유한요소모델링을 이용하여 임플란트/악골 복합체에 대해 임플란트 장축에 평행한 방향으로 치관 교합면의 중심부에 수직 하중 100 N이 작용할 때 변연골의 최대압축응력을 산출하여 비교 하였다. 결과: 여섯 개의 모든 실험 임플란트 모델에서 변연골의 응력집중이 관찰되지 않았다. 변연골 응력은 임플란트 경부 역사면의 폭과 높이의 차이에 따라 달라지는 것이 관찰되었으며 사면각이 클수록 응력 집중이 증가하는 경향을 보였다. 결론: 임플란트 경부 역사면 디자인의 부여는 변연골 응력 분포 개선에 중요한 역할을 할 수 있을 것으로 여겨진다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.520-525
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• 2011

As worldwide concern stands on global warming and greenhouse gases from internal combustion engine, the interests in technologies for a highly efficient powertrain has been increased. Concurrently the investigation to improve the deteriorated NVH, a by-product of energy efficient powertrain, is conducted seriously. The NVH performance of a new type of active engine mount that offers increased advantages over a passive hydraulic mount is examined using a newly developed 6-DOF simulator. The simulator is in the shape of Hexapod Stewart Platform adopting LEMA, a new type of actuator which is patented and commercialized by ACT Inc,, the world wide leader in the design, development, and manufacture of high performance linear electro-magnetic actuators for active vibration control. The target vibration signals of an aimed vehicle at four engine mounts are measured and simulated by 6-DOF simulator at the laboratory. The resulting NVH performances of the new active mounting system at a vehicle and on a simulator are examined and compared. Even though the active mount performance of lab test demonstrates less effective than the result of a real vehicle test, vibration reduction is identified through the simulator.

• Earthquakes and Structures
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• 제7권4호
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• pp.571-586
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• 2014

This paper presents experimental and numerical study on seismic performance of a super tall steel tower structure. The steel tower, with a height of 388 meters, employs a steel space truss with spiral steel columns to serve as its main lateral load resisting system. Moreover, this space truss was surrounded by the spiral steel columns to form a steel mega system in order to support a 12-story platform building which is located from the height of 230 meters to 263 meters. A 1/40 scaled model for this tower structure was made and tested on shake table under a series of one- and two-dimensional earthquake excitations with gradually increasing acceleration amplitudes. The test model performed elastically up to the seismic excitations representing the earthquakes with a return period of 475 years, and the test model also survived with limited damages under the seismic excitations representing the earthquakes with a return period 2475 years. A finite element model for the prototype structure was further developed and verified. It was noted that the model predictions on dynamic properties and displacement responses agreed reasonably well with test results. The maximum inter-story drift of the tower structure was obtained, and the stress in the steel members was investigated. Results indicated that larger displacement responses were observed for the section from the height of 50 meters to 100 meters in the tower structure. For structural design, applicable measures should be adopted to increase the stiffness and ductility for this section in order to avoid excessive deformations, and to improve the serviceability of the prototype structure.

• 한국콘텐츠학회논문지
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• 제12권1호
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• pp.379-385
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• 2012

본 연구는 최근 들어 급속히 보급이 확산된 스마트폰을 이용하여 이를 치료실과 기공소간의 정보공유체계와 연계 활용하는 방안을 제시하는 것이 목적이다. 이를 위해 최근 모바일 플랫폼 기반의 개발환경을 소개하고 안드로이드 기반의 환자정보 공유체계의 주요 기능을 정의하여 이를 사용자 인터페이스의 설계를 통해 구현 하였다. 이를 실무에 적용한 결과 다음과 같은 결과를 얻을 수 있었다. 1. 스마트폰 등 현재 이슈가 되고 있는 정보화 기반기술을 치기공계에 적용할 수 있는 가능성을 제시하였다. 2. 환자의 구강에 대한 영상촬영 시 카메라와 PC를 연결하여 전송하는 프로세스를 개선함으로서 치료 실내의 정보 활용성이 개선되었다. 3. 환자의 구강정보는 촬영 즉시 서버로 전송되므로 영상화일의 오류를 저감할 수 있었다. 4. 임상에서의 보철물 제작 시 스마트폰에 보철물 이미지를 표출한 상태로 작업함으로서 작업의 효율성이 개선되었다.

• 한국해양공학회지
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• 제19권5호
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• pp.1-15
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• 2005

The motion behaviors including hydrodynamic interaction and mechanical coupling effects on multiple-body floating platforms are simulated by using a time domain hull/mooring/riser coupled dynamics analysis program. The objective of this study is to evaluate off-diagonal hydrodynamic interaction effects and mechanical coupling effects on tandem moored FPSO and shuttle taker motions. In the multiple-body floating platforms interaction, hydrodynamic coupling effects with waves and mechanical coupling effects through the connectors should be considered. Thus, in this study, the multiple-body platform motions are calculated by Combined Matrix Method (CMM) as well as Separated Matrix Method (SMM). The advantage of the combined matrix method is that it can include all the 6Nx6N full hydrodynamic and mechanical interaction effects among N bodies. Whereas, due to the larger matrix size, the calculation time of Combined Matrix Method (CMM) is longer than the Separated Matrix Method (SMM). On the other hand, Separated Matrix Method (SMM) cannot include the off-diagonal 6x6 hydrodynamic interaction coefficients although it can fully include mechanical interactions among N bodies. To evaluate hydrodynamic interaction and mechanical coupling effects, tandem moored FPSO and shuttle tanker is simulated by Combined Matrix Method (CMM) and Separated Matrix Method (SMM). The calculation results give a good agreement between Combined Matrix Method (CMM) and Separated Matrix Method (SMM). The results show that the Separated Matrix Method (SMM) is more efficient for tandem moored FPSO and shuttle tanker. In the numerical calculation, the hydrodynamic coefficients are calculated from a 3D diffraction/radiation panel program WAMIT, and wind and current forces are generated by using the respective coefficients given in the OCIMF data sheet.

• 대한치과보철학회지
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• 제48권3호
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• pp.224-231
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• 2010

연구 목적: 본 연구에서는 임플란트 경부 디자인의 측면에서 미세나사, 치은 관통부의 곡면 디자인 적용 및 경부 역사면 부여효과를 직접 비교하여 정량적인 평가를 하고자 하였다. 연구 재료 및 방법: 직경 4.1 mm, 길이 10 mm 의 매립형 (submerged) 고정체 (Dentis Co., Daegu, Korea)를 기본 형상으로 설정하였다. 실험 모델로는 대조 모델의 경부 주위, 즉 치은 관통부/지대주 체결 방법에 변화를 준 다섯 가지 경우로 설정하였다 (실험 모델 I: 경부측 3 mm에 높이 0.15 mm, 피치 0.3 mm의 미세나사 (microthread)가 가공된 모델, 실험 모델II: 실험 모델 I 과 동일한 고정체이나, 매립형이 아니라 1-stage 형 (internal type) 디자인을 가진 미세나사가 가공된 모델, 실험 모델 III: 매식부 나사산은 대조 모델과 동일하나 1-stage 형 경부 디자인을 가지는 미세나사가 가공되지 않은 모델, 실험 모델 IV: 일체형 (one piece system) 임플란트로 치은 관통부에 3 mm 직경의 만곡 (concavity)형상을 갖는 모델, 실험 모델 V : 매식부 나사산 및 지대주는 대조 모델과 동일하나 고정체 platform 가장 자리에 높이 1 mm 의 역사면 (reverse bevel)을갖는모델). 유한요소해석을 위해 PC용으로 출시된 상용 프로그램인 NISA II/Display III (EMRC, Troy, MI, USA)를 사용하여, 축대칭으로 임플란트/악골 조합을 모델링하였다. 고정체 형상은 동일하나 경부 (및 치은 관통부) 디자인에 차이가 있는 여섯 종의 임플란트 (대조 모델 + 다섯 종 실험 모델)를 9 mm 폭경의 악골에 식립하고 임플란트 장축에 대해 30도의 각도를 갖는 100 N의 하중을 받는 조건으로 임플란트/골 복합체의 응력을 해석하였다. 결과:실험 모델 I과 실험 모델 IV에서 변연골 응력이 약간 낮았으나 실험 모델 II, III, 실험 모델 V는 대조 모델보다 변연골 응력이 높았다. 최대 절점응력이 기록된 임플란트로부터 0.2 mm 떨어진 위치에서의 응력은 실험 모델 III에서 21.11 MPa로 가장 높았고 실험 모델 II와 실험 모델 V는 비슷한 수준으로 각각 18.39 MPa, 17.88 MPa이었으며 실험 모델 I, IV는 대조모델의 15.09 MPa 보다 약간 낮은 14.78 MPa, 14.63 MPa 였다. 결론: 경부의 미세나사와 치은 관통부의 곡면 (concavity) 부여가 변연골의 응력집중 방지에 효과가 있는 것으로 분석되었다.