• 한국자동차공학회논문집
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• 제9권2호
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• pp.107-115
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• 2001

It is required more precise analysis for practical load because of complexities and varieties of vehicle structure. To establish the numerical model, many researchers have been developed designing tools for linking F.E. Analysis results and experimental results. There studies have generally focused on each experimental method or analytical method separately. There are few studies based on both methods. This paper conceives new procedure for the determination of the load direction and magnitude applied on mechanical structures. New procedure is the combination of the analytical and empirical method with analyzed strain by F.E. Analysis under unit load and with measured principal stress by strain gages under driving load, respectively. In this paper, we theorize the procedure of practical load determination and make the validity and the practicality of the procedure with the application to T-shape jointed structure. F.E. Analysis is conducted to get the principal stress on arbitrary points in the F.E. model of T-shape joint under unit load. Then experiment is carried out to get the principal stress on the same points of F.E. model. To demonstrate the actual driving condition, the load conditions are bending and torsion. From these two data sets, the magnitude, the direction and the position of load can be obtained. Theory and practice do not always coincide; since there are some errors such as ill-poseness, measuring error and modeling error in experimental data, we examine the proper method of error minimization.

• Journal of Astronomy and Space Sciences
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• 제30권4호
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• pp.223-230
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• 2013

Sudden enhancements of daytime NmF2 appeared in Anyang ionosonde data during summer seasons in 2006-2007. In order to investigate the causes of this unusual enhancement, we compared Anyang NmF2's with the total electron contents (GPS TECs) observed at Daejeon, and also with ionosonde data at at mid-latitude stations. First, we found no similar increase in Daejeon GPS TEC when the sudden enhancements of Anyang NmF2 occurred. Second, we investigated NmF2's observed at other ionosonde stations that use the same ionosonde model and auto-scaling program as the Anyang ionosonde. We found similar enhancements of NmF2 at these ionosonde stations. Moreover, the analysis of ionograms from Athens and Rome showed that there were sporadic-E layers with high electron density during the enhancements in NmF2. The auto-scaling program (ARTIST 4.5) used seems to recognize sporadic-E layer echoes as a F2 layer trace, resulting in the erroneous critical frequency of F2 layer (foF2). Other versions of the ARTIST scaling program also seem to produce similar erroneous results. Therefore we conclude that the sudden enhancements of NmF2 in Anyang data were due to the misrecognition of sporadic-E echoes as a F-layer by the auto-scaling program. We also noticed that although the scaling program flagged confidence level (C-level) of an ionogram as uncertain when a sporadic-E layer occurs, it still automatically computed erroneous foF2's. Therefore one should check the confidence level before using long term ionosonde data that were produced by an auto-scaling program.

• 대한공업교육학회지
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• 제40권2호
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• pp.155-174
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• 2015

본 연구의 목적은 중등단계 직업교육에서의 발명 지식재산 교육내용에 대한 교사의 교육요구도 우선 순위를 분석하여, 중등단계 직업교육에서의 발명 지식재산교육이 효과적으로 이루어 질 수 있는 토대가 되는 교원의 역량 개발을 위한 직무 연수 프로그램 개발에 기초 자료를 제공하는 것이다. 이를 위해서 담당 교사 인식에 기반한 중등단계 직업교육에서의 발명 지식재산 교육내용에 대한 교육요구도와 이러한 교육요구도의 우선 순위를 분석하여 제시하였다. 본 연구의 구체적인 결과를 제시하면 다음과 같다. 첫째, 중등단계 직업교육에서 발명 지식재산 교육내용에 대한 담당 교사의 교육 요구도 평균은 5.02로 나타났다. 교육요구도가 전체 평균보다 높은 교육내용 항목은 23개이고, 이들 항목과 항목별 평균은 F4(특허 청구 범위) 6.72, F5(명세서 수정 및 보충) 6.46, F2(특허 도면 작성) 6.39, F3(특허명세서와 요약서 작성) 6.31, A5(발명 기법과 활동) 6.27, E6(발명 디자인 프로젝트) 6.15, H3(발명품 사업화) 5.97, F1(특허 정보 및 출원) 5.90, E5(디자인 권리화) 5.78, E3(발명 디자인의 디자인 과정) 5.77, A4(발명과 문제 해결) 5.57, G2(특허 조사 및 분류) 5.47, C2(발명 문제 해결 사고 기법) 5.45, E4(발명 디자인 제품 제작) 5.45, B5(발명특허 프로젝트) 5.42, A2(창의성 개발) 5.26, C4(발명 문제 해결 프로젝트) 5.26, H4(발명품 마케팅) 5.26, H2(발명품 사업성 분석) 5.20, D4(발명과 경영) 5.16, C3(문제 해결 활동) 5.14, E2(발명 디자인의 발상과 표현) 5.11, B3(발명기법의 실제) 5.08 순으로 나타났다. 둘째, 중등단계 직업교육에서 발명 지식재산 교육내용에 대한 담당 교사의 교육 요구도 우선 순위는 1순위에 해당하는 교육내용 항목은 13개, 2순위는 10개, 3순위는 17개로 나타났다. 1순위에 해당하는 교육내용 항목은 A4(발명과 문제 해결), A5(발명 기법과 활동), B5(발명특허 프로젝트), C2(발명 문제 해결 사고 기법), C4(발명 문제 해결 프로젝트), E3(발명 디자인 과정), E4(발명 디자인 제품 제작), E5(디자인 권리화), E6(발명 디자인 프로젝트), F1(특허 정보 및 출원), F2(특허 도면 작성), F3(특허명세서와 요약서 작성), H3(발명품 사업화)이다. 2순위에 해당하는 교육내용 항목은 A2(창의성 개발), B3(발명기법의 실제), C3(문제 해결 활동), D4(발명과 경영), E2(발명 디자인의 발상과 표현), F4(특허 청구 범위), F5(명세서 수정 및 보충), G2(특허 조사 및 분류), H2(발명품 사업성 분석), H4(발명품 마케팅)이다. 3순위는 1, 2 순위를 제외한 교육내용이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1994년도 봄 학술발표회 논문집
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• pp.17-24
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• 1994

In the analysis pre-cast large panel structures, we can use the new discrete analyzing method to be consisted of rigid bodies. Because the pre-cast panels we still more rigid than the connection, the rigid element method is more efficient numerical method than F. E. M. The characteristics of R. E. M. is that strains in element are not occurred by external loadings and the deformation of the structures by external loadings is transmitted through springs around elements. In this study, we focus on the comparison of the results from the R. E. M. and the F. E. M. in order to establish the validity of the R. E. M. to analysis of pre-cast panel structures.

• Nuclear Engineering and Technology
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• 제55권11호
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• pp.4048-4056
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• 2023

The feasibility of using the Monte Carlo code MCS to generate multigroup cross sections for nodal diffusion simulations RAST-F of liquid metal fast reactors is investigated in this paper. The performance of the MCS/RAST-F code system is assessed using steady-state simulations of the ANTS-100e core. The results show good agreement between MCS/RAST-F and MCS reference solutions, with a keff difference of less than 77 pcm and root-mean-square differences in radial and axial power of less than 0.5% and 0.25%, respectively. Furthermore, the MCS/RAST-F reactivity feedback coefficients are within three standard deviations of the MCS coefficients. To validate the internal thermal-hydraulic (TH) feedback capability in RAST-F code, the coupled neutronic/TH1D simulation of ANTS-100e is performed using the case matrix obtained from MCS branch calculations. The results are compared to those obtained using the MARS-LBE system code and show good agreement with relative temperature differences in fuel and coolant of less than 0.8%. This study demonstrates that the MCS/RAST-F code system can produce accurate results for core steady-state neutronic calculations and for coupled neutronic/TH simulations.

• 열처리공학회지
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• 제7권2호
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• pp.103-110
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• 1994

It is well-known that the analysis of temperature distribution is substantilly important in optimal design of quenching process. The unsteady state temperature gradients generated during the quenching process were numerically calculated by the Finite Element Method(F. E. M.). Formulations of F. E. M. based weighted residural method were presented for the analysis of the two dimensional heat conduction problem. In the process of calculation, the temperature dependency of physical properties of the material was in consideration. At early stage of the quenching process, the abrupt temperature gradient has been shown in the surface of the carbon steel(SM45C).

• 대한기계학회논문집
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• 제8권4호
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• pp.385-393
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• 1984

본 연구에서는 다트식 낙하충격 시험에 있어서 인성의 강소성 플라스틱 재료 의 준정적 선형의 점탄성 모델이 구성되어 해석되었다. 완화계수함수, E(t)=E$_{f}$ +(E$_{o}$ -E$_{f}$ )e$^{-t/tR}$ 형태의 점탄성 재료의 수정된 Maxwell요소모델을 근거 로 충격속도, 파괴에너지, 임계응력등의 중요변수들의 상대적 종속성이 근사계산으로 평가되었다.

• 충청수학회지
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• 제26권4호
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• pp.853-867
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• 2013

In this paper we study the cardinality of the dot product set generated by two subsets of vector spaces over finite fields. We notice that the results on the dot product problems for one set can be simply extended to two sets. Let E and F be subsets of the d-dimensional vector space $\mathbb{F}^d_q$ over a finite field $\mathbb{F}_q$ with q elements. As a new result, we prove that if E and F are subsets of the paraboloid and ${\mid}E{\parallel}F{\mid}{\geq}Cq^d$ for some large C > 1, then ${\mid}{\Pi}(E,F){\mid}{\geq}cq$ for some 0 < c < 1. In particular, we find a connection between the size of the dot product set and the number of lines through both the origin and a nonzero point in the given set E. As an application of this observation, we obtain more sharpened results on the generalized dot product set problems. The discrete Fourier analysis and geometrical observation play a crucial role in proving our results.

• 한국분무공학회지
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• 제28권3호
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• pp.143-149
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• 2023

Amidst the drive towards carbon neutrality, interest in renewable synthetic e-fuels is rising rapidly. These fuels, generated through the synthesis of atmospheric carbon and green hydrogen, offer a sustainable solution, showing advantages like high energy density and compatibility with existing infrastructure. The physical properties of e-fuels can be different from those of conventional gasoline based on manufacturing methods, which requires investigations into how the physical properties of e-fuels affect the fuel injection characteristics. This study performs a comparative analysis between conventional and Fischer-Tropsch (F-T) synthetic gasoline (e-gasoline) across various fuel temperatures, including the cold start condition. The fuel properties of F-T synthetic and conventional gasoline are analyzed using a gas chromatography-mass spectrometry technique and the injection rates are measured using a Bosch-tube injection rate meter. The F-T synthetic gasoline exhibited higher density and kinematic viscosity, but lower vapor pressure compared to the conventional gasoline. Both fuels showed an increase in injection rate as the fuel temperature decreased. The F-T synthetic gasoline showed higher injection rates compared to conventional gasoline regardless of the fuel temperature.

• Nuclear Engineering and Technology
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• 제4권3호
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• pp.214-222
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• 1972

광학급 LiF단결정의 열형광유선은 r선조사선양이 증가함에 따라서 변화한다. 즉 선량이 적을 때는 2개의 glow peak를 가지나, 선양이 정차 증가하여 10$_{5}$ rontgen 정도에 이르면 5개의 glow peak를 나타낸다. 이들 glow peak에 대응하는 energy 준위 Ei(i=1,2,3,4, 및 5)는 전도대 밑으로 부터의 깊이로 표시할 때 다음과 같은 값을 갖는다. 이들 E$_i{$의 값은 가열속도 $\theta_1$=6.6$^{\circ}C$/sec와 $\theta_2$=3.4$^{\circ}C$/sec에 대한 glow peak의 온도를 얻은 다음, Randall-Wilkins의 이론에 따라서 계산되었다. 광학급 LiF단결정에서 E$_1$과 E$_2$이외의 전자 trap은 열적으로 불안정하며 LiF(Mg) 열형광선양계에 불가결한 것으로 되어있는 sensitization의 효과가 거의 없다. LiF(Mg)는 $\theta$=6.6$^{\circ}C$/sec 일때, 17$0^{\circ}C$와 23$0^{\circ}C$에 glow peak를 나타내며 이들에 대응하는 전자 trap E$_4$와 E$_{5}$ 이외에 방사선이 조사됨에 따라서 E$_1$, E$_2$, E$_3$ 및 E$_{6}$의 전자 trap이 형성되며 이들 값은 다음과 같다. LiF(Mg)에서 방사선상해 때문에 형성된 E$_1$, E$_2$, E$_3$및 E$_{6}$는 모두 상당히 열적으로 안정하며, sensitization과정에서 형성된다. 이 안정한 6준위계에서 LiF(Mg)예 의한 방사선 선양측정이 시행되어야 한다. E$_1$,E$_2$,E$_3$ 및 E$_{6}$의 안정성은 LiF결정내의 $Mg^{$ ++/ 불순물의 영향으로 사료된다. 광학급 LiF단결정의 열형광에서 r선양의 대수표시양과 전열형광양의 대수표시 사이에 비선형성을 나타낸다. 그러나 열적으로 안정한 12$0^{\circ}C$ glow peak만을 고려하여 r선양의 대수표시양과 12$0^{\circ}C$ slow peak의 높이의 대수표시량 사이에서 비선형성이 감소되어, LiF(Mg)에 대한 곡선과 매우 유사한 곡선을 얻게 된다.