• 한국추진공학회지
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• 제25권3호
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• pp.1-13
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• 2021

추력이 최적화된 노즐의 초음속 유동장에 대한 노즐벽면각도의 영향이 수치해석적으로 조사되었다. 30톤급 로켓엔진의 연소기와 작동조건이 최적노즐형상을 조사하기 위하여 선택되었다. 연소생성물의 노즐유동은 케로신-액체산소의 이동평형계산에 의해서 구현되었다. 노즐벽면 각도의 변화는 내부충격파 및 2차 충격파의 발달형태를 다르게 유도하였다. 내부충격파가 노즐출구에서 특정위치에 있을 때 최적노즐이 얻어졌다. 최적노즐에 대한 노즐벽면 각도들은 충격파를 고려하지 않고 얻어진 최적노즐 형상과 매우 유사하게 얻어졌다.

• International Journal of Advanced Culture Technology
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• 제10권4호
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• pp.28-38
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• 2022

Virtual idols have aroused wide attention as a novel product of the idol industry in the digital era over the past few years. The population of China determines that virtual idols have a huge fan market. As a digital cultural product closely connected with fans, virtual idols are im-portant to gain insights into the correlation between fan satisfaction and virtual idol functions. In accordance with the KANO demand model, this study first classifies and explains the specific functions of virtual idols into four quadrants, including attractive, must-be, 1D (One-Dimensional), and indifferent. Subsequently, the satisfaction of fans of virtual idols with specific functions in each quadrant are analyzed using a questionnaire. This study suggests that virtual idols have one at-tractive quality, three 1D quality, two must-be quality, and five indifferent quality functional elements. This study qualitatively analyzes the functional elements of virtual idols through fan satisfaction based on the KANO model, which provides valuable help for future research in the field of virtual idols and producers in this field.

• 한국측량학회지
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• 제40권4호
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• pp.351-357
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• 2022

In this study, a direction for deregulation that can increase the use of drones in the field of spatial information is presented. Regulations and administrative procedures for drone operation showed similar procedures in Japan, the United States, and Korea, such as reporting flight equipment, driver's license, and prohibition of flying within a specific flight zone. In the United States, policies to encourage the use of commercial drones have been implemented, and Japan has slightly tightened regulations on drone operation to protect the Olympics and important national facilities. As a result of the study, in the area where drone operation is restricted for geospatial data construction, Korea was setting the largest area, and GIS analysis showed that Korea's drone flight restricted area was more than 19.4% of the country's land area. In order to increase the utilization of drones in the construction and utilization of spatial information in the future, it is necessary to reset the drone flight restriction zone and reduce the area of the drone flight restriction zone. In addition, it was found that Korea is the only country that has formal and specific regulations on geospatial information security management. In order to increase the construction of geospatial information using drones, it is necessary to ease GSD (Ground Sample Distance)regulations.

• Computers and Concrete
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• 제33권4호
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• pp.445-469
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• 2024

The Federal Highway Administration (FHWA) has recommended the use of AASHTOWare Pavement Mechanistic-Empirical Design (PMED) software for Roller-Compacted Concrete (RCC) pavement design, but specific calibration for RCC is missing. This study investigates the software's capacity to predict the long-term performance of RCC roadways within the framework of conventional concrete pavement calibration. By reanalyzing existing RCC projects in several U.S. states: Colorado, Arkansas, South Carolina, Texas, and Illinois, the study highlights the need for specific calibration tailored to the unique characteristics of RCC. Field observations have emphasized occurrence of early distresses in RCC pavements, particularly transverse-cracking and joint-related issues. Despite data challenges, the AASHTOWare PMED software exhibits notable correlation between its long-term predictions and actual field performance in RCC roadways. This study stresses that RCC applications with insufficient joint spacing and thickness are prone to premature cracking. To enhance the accuracy of RCC pavement design, it is essential to discuss the inclusion of RCC as a dedicated rigid pavement option in AASHTOWare PMED. This becomes particularly crucial when the rising popularity of RCC roadways in the U.S. and Canada is considered. Such an inclusion would solidify RCC as a viable third option alongside Jointed Plain Concrete Pavements (JPCP) and Continuously Reinforced Concrete Pavements (CRCP) for design and deployment of rigid pavements. The research presents a roadmap for future calibration endeavors and advocates for the integration of RCC pavement as a distinct pavement type within the software. This approach holds promise for achieving more precise RCC pavement design and performance predictions.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.368-368
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• 2012

We report solution-processed, high-performance single-crystal organic nanowire transistors fabricated from a novel indolocarbazole (IC) derivative. The direct printing process was utilized to generate single-crystal organic nanowire arrays enabling the simultaneous synthesis, alignment and patterning of nanowires using molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. These new molecules are particularly suitable for p-channel organic field-effect transistors (OFETs) because of the high level of crystallinity usually found in IC derivatives. Selected area diffraction (SAED) and X-ray diffraction (XRD) experiments on these solution-processed nanowires showed high crystallinity. Transistors fabricated with these nanowires gave a hole mobility as high as 1.0 cm2V-1s-1 with nanowire arrays with the direct printing process.

• Journal of Magnetics
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• 제19권1호
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• pp.72-77
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• 2014

This paper proposes an indirect fault detection method for an onboard degaussing coil system, installed to reduce the underwater magnetic field from the ferromagnetic hull. The method utilizes underwater field signals measured at specific magnetic treatment facilities instead of using time-consuming numerical field solutions in a three-dimensional space. An equivalent magnetic charge model combined with a material sensitivity formula is adopted to predict fault coil locations. The purpose of the proposed method is to yield reliable data on the location and type of a coil breakdown even without information on individual degaussing coils, such as dimension, location and number of turns. Under several fault conditions, the method is tested with a model ship equipped with 20 degaussing coils.

• Structural Engineering and Mechanics
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• 제73권6호
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• pp.621-629
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• 2020

The present paper aims to study the influence of the magnetic field and initial stress on the 2-D problem of generalized thermo-viscoelastic material with voids subject to thermal loading by a laser pulse in the context of the Lord-Shulman and the classical dynamical coupled theories. The analytical expressions for the physical quantities are obtained in the physical domain by using the normal mode analysis. These expressions are calculated numerically for a specific material and explained graphically. Comparisons are made with the results predicted by the Lord-Shulman and the coupled theories in the presence and absence of the initial stress and the magnetic field.

• STI Policy Review
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• 제1권4호
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• pp.1-20
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• 2010

This paper explores the role of entrepreneurship education in a modern economy and how the government, academic, and nonprofit sectors in the United States have responded to this growing field. There are several sectors that play important roles in the entrepreneurship education landscape in the United States. Over the past decade, there has been increasing participation of Federal and state governments. This recent trend suggests the field may be increasing in maturity and legitimacy, showing promise for expanding the reach of entrepreneurship education programs. Programs sponsored by nonprofit organizations and private foundations complement government initiatives and display an effective means of leveraging knowledge and resources across the relevant sectors. Thus, new initiatives, whether initiated by government or academia, should learn from the successes of this sector as well as be carefully considered within the context of existent programs and services. Nonetheless, the potentially dynamic environment of the entrepreneurship education field in the United States offers a specific opportunity to leverage the experience in mentorship activities at the post-secondary education to address a possible gap in these activities at the secondary education level.

• 한국임상수의학회지
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• 제16권1호
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• pp.75-79
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• 1999

Magnetic resonance imaging (MRI) is an imaging technique used to produce high quality images of the inside of the animal body. MRI is based on the principles of nuclear magnetic resonance (NMR) and started out as a tomographic imaging technique, that is it produced an image of the NMR signal in a thin slice through the animal body. The animal body is primarily fat and water, Fat and water have many hydrogen atoms. Hydrogen nuclei have an NMR signal. For these reasons magnetic resonance imaging primarily images the NMR signal from the hydrogen nuclei. Hydrogen protons, within the body align with the magnetic field. By applying short radio frequency (RF) pulses to a specific anatomical slice, the protons in the slice absorb energy at this resonant frequency causing them to spin perpendicular to the magnetic field. As the protons relax back into alignment with the magnetic field, a signal is received by an RF coil that acts as an antennae. This signal is processed by a computer to produce diagnostic images of the anatomical area of interest.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2006년도 추계 학술발표회
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• pp.229-240
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• 2006

Most of rock slopes contain a lot of discontinuities which have a specific direction and various characteristics. In general, the collapses of the rock slopes occur when the sliding dip of the discontinuity is higher than the internal friction angle and also smaller than the free-air plane of the slope. If a general slope theory is only considered in the case of field exploration of the slopes, there is a possibility that dangerous slopes might be estimated as stable slopes. We mention problems that can easily fail to notice something in field exploration and propose the alternatives to solve the problems through the case studies.