• Journal of the Korean Society for Railway
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• v.6 no.2
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• pp.22-32
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• 2003

차륜없이 전자석에 의해 부상하고, 리니어모터에 의해 추진하는 시스템이다. HSST의 가장 큰 장점은, 접촉지짖에 의한 저소음 및 공기저항외에는 주행저항이 없기 때문에 고속주행이 가능하다. HSST도 당초에는 최고속도 200∼300km/h 정도의 시스템 HSST-200, HSST-300 타입을 목표로 개발을 진행해왔지만, 최근에는 급구배 및 급곡선 통과가 가능한 특성을 활용하여 도시내 교통을 대상으로 하는 최고속도 100km/h 정도의 시스템 HSST-100 타입 개발에도 주력함으로써 실용화에 달하고 있다. 경량전철로서의 취급하고 있는 시스템은 HSST-100 타입이다.(중략)

• Transactions of Materials Processing
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• v.1 no.2
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• pp.40-51
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• 1992

냉간단조에 의한 새로운 헬리컬기어 성형공정이 제시되었다. 원형봉재로 부터 헬리컬기어를 압출함에 있어서 압출압력을 계산하기 위하여 상계정리를 적용하여 수치계산하고, 수치해석 결과와 압출하려는 기어의 금형을 설계 제작하여 실험한 결과를 비교 검토하고자 한다. 이론해석상 다이형상으로 인벌류트곡선을 사용한 이론해는 실험결과와 잘 일치하였다. 그리고, 다이의 형상을 평기어부와 헬리컬기어부의 이중구조로 된 신공정이 헬리컬기어부로만 된 사만타공정과 비교해서 금형강도를 향상시킴으로써 다이수명은 증가되었고, 자동차 변속기용으로 헬리컬기어는 KS 기어급수 4~5 급의 정밀도에 해당하는 기어를 가공했다. 이는 사만타공정의 정밀도 보다 향상된 결과를 얻었다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.631-645
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• 2002

●정의 정척레일을 연속 용접하여 1개의 레일길이를 200m 이상으로 부설한 레일 ●장대레일화 - 차량 시동/제동하중에 의한 교축방향 수평력 작용 - 기존 : 수평력 배분을 위해 단순교로 시공(레일 이음매) - 현재 : 장대레일화 ● 장점 -유지보수비 절감 -승차감 향상(충격/소음 저감) -고속화 및 운행 안전성 향상 ●단점 -큰 레일 축력(파단/좌굴) -교량부, 급곡선부, 분기부 - 장대레일 종하중(하부구조) (중략)

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.597-601
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• 2009

우리나라 하천의 중류나 상류는 대부분 산지로 되어 있어서 하천경사가 급하고 하상재료가 크며 지질 및 지형적인 영향을 받아 구속사행이 발달 되어 있는 산지하천이다. 산지하천은 홍수 시 만곡수충부 외측에서 홍수위 상승에 따른 범람과 유속 및 소류력에 의한 하상세굴이 발생한다. 특히 강원도는 산지하천을 따라서 도로가 발달되어 있기 때문에 하천피해는 도로피해와 직결되는 경우가 많다. 산지하천 수충부의 홍수피해를 줄이기 위해서는 호우에 따른 하천의 홍수위 및 하상 변동에 대한 자료가 필요하나 산지하천 특성을 고려한 관련 연구가 미흡한 실정이다. 본 연구에서는 산지하천 발달특성을 평가하기 위한 기초연구로서 유역의 면적-고도곡선을 평가하고자 한다. 산지하천은 하상을 구성하는 재료가 모래에서부터 전석에 이르기까지 그 크기가 매우 다양하게 분포되어 있어 일반 모래와 자갈이 주를 이루는 평지하천과 현저히 다르다. 하천유역의 면적-고도곡선은 유역의 지질 발달상을 판단하거나 홍수효과 또는 지형의 침식과 퇴적 등을 분석하는데 유효한 방법이다. 강원도 영동지역과 영서지역을 발원지로 하는 하천의 면적과 고도관계를 조사하였으며 이를 위하여 영서지역은 제1차 하천인 한강과 그 주요 지류 21개 하천, 영동지역은 제1차 하천 6개와 그 지류 3개 하천을 선정하고 무차원 면적-고도곡선을 작성하여 유역의 발달단계를 분석하기 위한 면적고도 발달계수를 정의하였다. 골지천을 제외한 모든 조사대상 하천에서 최대표고의 70%이상인 지역이 전체 유역면적의 10%미만을 차지하여 우리나라 하천유역이 상류의 경우 전형적인 장년기에서 노년기 지형으로 발달한 것으로 확인할 수 있었다. 그러나 유역의 하류지역은 이미 유년기적인 특성을 보이고 있는 것으로 판단된다. 또한 영동 보다는 영서지역 하천이 하류에서 유년기적 특성이 다소 크고 상류는 장년기가 많은 것으로 분석되었다.

• Journal of Korea Water Resources Association
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• v.32 no.4
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• pp.417-426
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• 1999

A series of numerical experiments is performed to compare the characteristics of outflow hydrograph using linear and nonlinear Muskingum-Cunge methods for two cases: (a) sinusoidal inflow hydrographs and (b) rainfall inputs. The nonlinear method shows the steepening of the rising limb, coupled with a corresponding flattening of the receding limb. The linear method conserves mass exactly. In contrast, the nonlinear method is subject to a gain and a loss of mass. The loss of mass and the subsidence of peak outflow increases with a mild slope, a small baseflow $q_b$ and a large peak inflow to baseflow ratio $q_p/q_b$. A shock wave and associated numerical instability results in the increase of mass for a steep slope and a large $q_p/q_b$ ratio. While the linear method depends on the reference flow per unit-width, the nonlinear method depends on a baseflow and the $q_p/q_b$ ratio. It is found that, unlike for the sinusoidal inflow, the outflow for the rainfall inputs conserves mass fairly exactly in the nonlinear method.

• Journal of Korean Society of Forest Science
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• v.68 no.1
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• pp.11-17
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• 1985

Height growth curve to be required for estimating site index was formulated with 10 models based on the average tree height and tree age. Among them, the model of $H=K-ab^A$ was evaluated to be best fit for estimating average tree height(H) with tree age (A). Equations, $H=28.364-26.125(0.818)^A$ and $H=26.331-25.125(0.886)^A$, were situated from the model for estimating average tree height of Larix leptolepis and Pinus koraiensis, respectively (in this case the tree age was categorized into 0 for 5 -year- old tree, 1 for 10 -year- old tree and 2 for 15 -year- old tree ect.). Result of comparing the site indices calculated by the Bryant method, it was proved that the site index of Larix leptolepis was estimated higher than that of Pinus koraiensis within the limits of site index class 6 to 18. On the contrary the site index of Pinus koraiensis turned out to surpass that of Larix leptolepis at the site index class 20 or over.

• Fire Science and Engineering
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• v.33 no.6
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• pp.20-27
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• 2019

In this study, a new function with higher accuracy for fire heat release rate prediction was developed. The 'αt²' curve, which is the major exponential function currently used for fire engineering calculations, must be improved to minimize the prediction gap that causes fire system engineering inefficiency and lower cost-effectiveness. The newly developed prediction function was designed to cover the initial fire stage that features rapid growth based on logistic function theory, which has a more logical background and graphical similarity compared to conventional exponential function methods for 'αt²'. The new function developed in this study showed apparently higher prediction accuracy over wider range of fire growth durations. With the progress of fire growth pattern studies, the results presented herein will contribute towards more effective fire protection engineering.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3155-3160
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• 2010

Nowadays, most car manufactures have tried to improve fuel efficiency and corrosion resistance of car body. Therefore, use of high strength steels and coated steel becomes more and more increased. In this study, spot weld characteristics according to lap sequence of sheets were analyzed using simulation method for three different steel sheet of car body which were EDDQ class coated steel with 0.7t, high strength steel 440R with 1.2t and advanced high strength steel DP 590 with 1.0t. Using simulation, weldability was evaluated by nugget size of welded zone according to nugget growth curve and welding current with respect to lap sequence of sheets. Contact resistance of each sheets contact point was used to analyze formation of nugget and optimal lap sequence was suggested.

• Journal of Korean Society of Forest Science
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• v.103 no.3
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• pp.383-391
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• 2014

Long-term changes in the hydrological characteristics of a small forest watershed were examined using a master baseflow recession curve and the measured rainfall-runoff data from the experimental forest watershed in the measured years 2003-2011. The results of the study showed that the recession coefficient of direct runoff was lower than that of baseflow. In small forested watershed, the direct flow was lower than that of large scale watershed, flow due to its shorter period of occurrence. And baseflow was similar to large scale watershed's. A regression equation $y=0.7528e^{-0.022x}$($R^2=0.8938$, range 0.3~0.8 mm) was obtained using the master baseflow recession curve for the study period and the recession coefficient was calculated as K = 0.978. Changes between master baseflow recession curve and runoff showed great association and relevance such as increasing runoff was associated with the gentle slope of master baseflow recession curve and decreasing runoff was associated with the slope of master baseflow recession curve contrary. In the later years of the study period, the slope of the master baseflow recession curve appreciably became more gentle due to increases in baseflow. This suggests that the forested experimental watershed exhibit improved structural functioning of normal flood control and reduced occurrence of water shortage problems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.573-579
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• 2001

The technology for characteristic analysis of device for high integration is changing rapidly. Therefore to understand characteristics of high -integrated device by computer simulation and fabricate the device having such characteristics became one of very important subjects. As devices become smaller from submicron to nanometer, we have investigated MOSFET built on an epitaxial layer(EPI) of a heavily-doped ground plane by TCAD(Technology Computer Aided Design) to develop optimum device structure. We analyzed and compared the EPI device characteristics such as impact ionization, electric field and I-V curve with those of lightly doped drain(LDD) MOSFET. Also, we presented that TCAD simulator is suitable for device simulation and the scaling theory is suitable at nano structure device.