• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.1187-1194
• /
• 2006

This study analyzed characteristics of soft ground consolidation according to depths of vertical drain. As the result, when the depth ratio of vertical drains (L/D) were 0.5, 0.7, and 1.0, consolidation characteristics were similar up to 70% in consolidation degree under one-dimensional drain condition. However, above this degree, consolidation speed became slower as L/D became smaller. Two-dimensional drain condition also showed a similar tendency, but when L/D was 1.0, the consolidation speed was relatively higher.

• 국제초고층학회논문집
• /
• 제1권2호
• /
• pp.81-85
• /
• 2012

Vertical meteorological conditions encountered by super tall buildings, such as wind speed, temperature and humidity, vary due to their height. Therefore, it is necessary to consider these environmental changes to properly estimate the heating and cooling loads, and to minimize the energy demands for HVAC in super tall buildings. This paper aims to analyze how vertical meteorological changes affect heating and cooling loads of super tall buildings by using numerical simulation. A radiosonde, which observes atmospheric parameters of upper air such as wind speed, wind direction, temperature, relative humidity and pressure, was used to provide weather data for the building load simulation. A hypothetical super tall building was used for the simulation to provide quantified characteristics of the heating and cooling loads, comparing the lower, middle and upper parts of the building. The effect of weather data on the heating and cooling loads in super tall building was also discussed.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2002년도 추계학술대회논문집
• /
• pp.393-398
• /
• 2002

In this study, the increasing gear boxes for the high speed vertical in-line centrifugal pump are developed through rotor dynamic analysis. The developed increasing gear boxes are two kinds for 18000rpm and 25000rpm at the output shaft. The gear sets suitable for high speed and high load are manufactured by investigating AGMA bending strength and AGMA surface strength severely. The rotor dynamic analysis on gear sets and bearings is performed in order to avoid the critical speeds and other troubles. As a result of study, the two increasing gear boxes for the high speed vertical in-line centrifugal pump are designed and manufactured.

• 한국철도학회논문집
• /
• 제14권6호
• /
• pp.545-554
• /
• 2011

철도교량을 주행하는 열차의 진동사용성 확보를 위해 Eurocode, 신간선기준, 호남고속철도 설계지침 등에서는 교량의 처짐과 차체연직가속도로 진동사용성 기준을 제시하고 있다. 호남고속철도 설계지침 경우 Eurocode를 인용하였기 때문에 향후 열차의 주행속도와 경간길이의 향상 및 확장에 맞추어 철도교량의 진동사용성 기준을 보완함에 있어 철도선진국들에 비해 상대적으로 뒤처질 것으로 예상된다. 따라서 고속철도교량 기술의 국외의존도를 줄이고 기술경쟁력을 확보하기 위하여 주행속도의 증가와 열차-교량 진동전달특성 등을 고려할 수 있는 철도교량의 진동사용성 허용처짐을 제시하기 위한 연구를 수행하였다. 본 논문에서는 매개변수 연구와 열차-교량 상호작용해석을 수행하여 주행속도의 증가에 따른 차체연직가속도와 교량변위의 상관관계를 파악하였으며 주행속도의 증가와 더불어 차체연직가속도가 증가하는 경향을 확인하고 가속도증폭계수를 제안하였다. 그리고 교량의 처짐형상과 진동을 정현파와 조화운동으로 가정하고 진동전달함수와 가속도증폭계수를 이용하여 고속철도교량의 진동사용성 허용처짐을 수식으로 전개하였다.

• 한국터널지하공간학회 논문집
• /
• 제15권6호
• /
• pp.559-570
• /
• 2013

고속철도는 대규모의 인원과 물자를 신속하게 운반할 수 있는 친환경 운송수단으로 각광받고 있다. 고속철도는 빠른 속도로 인해 선형이 제한되어 건설되므로 산이 많은 지형에서는 터널이 많아진다. 고속으로 주행중인 열차가 터널에 진입하는 경우에 터널내부에서 압력파가 발생하는데 이로 인해 이명감과 미기압파라는 문제가 발생한다. 터널 내의 압력파를 완화시키기 위한 다양한 방법 중 수직갱을 이용한 방법도 연구되고 있는데 이 연구에서는 TTMA라는 고속철도 터널 공기역학 해석프로그램을 이용하여 수직갱에 의한 수치해석모듈을 개발하였다. 이를 검증하기 위해 실측결과와 비교하여 그 성능을 검증하였으며 기존의 수치해석결과와 비교하여 그 우수성을 검증하였다.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제5권1호
• /
• pp.161-177
• /
• 2013

High-speed vessels require good resistance and seakeeping performance for safe operations in rough seas. The resistance and seakeeping performance of high-speed vessels varies significantly depending on their hull forms. In this study, three planing hulls that have almost the same displacement and principal dimension are designed and the hydrodynamic characteristics of those hulls are estimated by high-speed model tests. All model ships are deep-V type planing hulls. The bows of no.2 and no.3 model ships are designed to be advantageous for wave-piercing in rough water. No.2 and no.3 model ships have concave and straight forebody cross-sections, respectively. And length-to-beam ratios of no.2 and no.3 models are larger than that of no.1 model. In calm water tests, running attitude and resistance of model ships are measured at various speeds. And motion tests in regular waves are performed to measure the heave and pitch motion responses of the model ships. The required power of no.1 (VPS) model is smallest, but its vertical motion amplitudes in waves are the largest. No.2 (VWC) model shows the smallest motion amplitudes in waves, but needs the greatest power at high speed. The resistance and seakeeping performance of no.3 (VWS) model ship are the middle of three model ships, respectively. And in regular waves, no.1 model ship experiences 'fly over' phenomena around its resonant frequency. Vertical accelerations at specific locations such as F.P., center of gravity of model ships are measured at their resonant frequency. It is necessary to measure accelerations by accelerometers or other devices in model tests for the accurate prediction of vertical accelerations in real ships.

• 대한기계학회논문집B
• /
• 제30권3호
• /
• pp.278-286
• /
• 2006

Experiments were conducted to estimate the performance of drag force type vertical axis wind turbine with an opening-shutting rotor. It was operated by the difference in drag force generated on both sides of the blades. The rotational speed was measured by a tachometer in a wind tunnel and the tunnel wind speed was measured by using a pilot-static tube and a micro manometer. The performance test for a prototype was accomplished by calculating power, power coefficient, torque coefficient from the measurement of torque and rpm by a dynamometer controller. Various design parameters, such as the number of blades(B), blade aspect ratio(W/R), angle of blades$(\alpha)$ and drag coefficient acting on a blade, were considered for optimal conditions. At the experiment of miniature model, maximum efficiency was found at N=15, $\alpha=60^{\circ}$ and W/R=0.32. The measured test variables were power, torque, rotational speed, and wind speeds. The data presented are in the form of power and torque coefficients as a function of tip-speed ratio V/U. Maximum power was found in case of $\Omega=0.33$, when the power and torque coefficient were 0.14 and 0.37 respectively. Comparing model test with prototype test, similarity law by advance ratio for vertical axis wind turbine was confirmed.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2011년도 춘계학술대회 논문집
• /
• pp.1391-1392
• /
• 2011

• Advances in Computational Design
• /
• 제8권1호
• /
• pp.1-12
• /
• 2023

To consider the effects of the increasing speed of next-generation high-speed trains, the existing traffic safety code for railway bridges needs to be improved. This study suggests a numerical method of evaluating the new effects of this increasing speed on railway bridges. A prestressed concrete (PSC) box bridge with a 40 m span length on the Gyeongbu track sector is selected as a representative example of high-speed railway bridges in Korea. Numerical models considering the inertial mass forces of a 38-degree-of-freedom train and the interaction forces with the bridge as well as track irregularities are presented in detail. The vertical deflections and accelerations of the deck are calculated and compared to find the new effects on the bridge arising with increasing speed under simply and continuously supported boundary conditions. The ratios between the static and dynamic responses are calculated as the dynamic amplification factors (DAFs) under different running speeds to evaluate the traffic safety. The maximum deflection and acceleration caused by the running speed are indicated, and regression equations for predicting these quantities based on the speed are also proposed.

• 대한조선학회논문집
• /
• 제47권4호
• /
• pp.496-507
• /
• 2010

It is well known that when a high-speed planing craft travels in following seas it experiences long-periodic motions due to low encounter frequency, and it often loses its course keeping stability. Therefore, it is necessary to study the sea-keeping performance and stability of it in the following seas. In this paper, the vertical motions of a planing craft were measured in following regular waves, and the test results were compared with the theoretical results. In the case of the same encounter frequency, non-dimensionalized motion amplitudes become larger as Froude number is higher, and non-dimensionalized motion amplitudes in head waves are larger than those in following waves. The mean values of the motions in following waves are similar to the running attitudes of a craft in calm water at the same Froude number.