• 한국산학기술학회논문지
• /
• 제3권4호
• /
• pp.285-289
• /
• 2002

본 논문에서는 아이스크림용 아이스 콘에서 콘 부분을 만들기 위한 금형의 제작시 필요한 구조적 안정성을 평가 할 수 있는 유동해석을 수행하였다. 유동해석을 수행하기 위하여 상용 유한요소해석 코드인 ANSYS를 활용하였으며 내압조건, 경계조건, 구속조건 등을 고려하여 아이스 콘 금형 내부의 유동 흐름을 압력조건의 변화에 따라 구하였다.

• 대한기계학회논문집B
• /
• 제21권7호
• /
• pp.862-872
• /
• 1997

Ice formation in a horizontal circular cylinder has been studied numerically. From the numerical analysis results, it was found that there were three types of freezing pattern and that freezing phenomenon was affected largely by density inversion and cooling rate. The type of freezing pattern largely depends on the secondary flow which is generated by density inversion. When supercooling energy is released before the development of the secondary flow, the annular ice layer grows. If the energy is released when the secondary flow is considerably developed and the supercooled region is removed to the upper half part of the cylinder, an asymmetric ice layer grows. And if the energy is released after perfect development of the secondary flow, instantaneous dendritic ice formation over the full region occurs. Furthermore, this secondary flow was found to have an effect on heat transfer characteristics. The heat transfer rate becomes small at the instant when the secondary flow is generated, but becomes large with the development of the flow. It's concluded that for the facilitation of heat transfer it is desirable to keep water in liquid phase until the secondary flow is perfectly developed. This study gave an instruction of performance improvement of capsule type ice storage tank.

• 대한조선학회논문집
• /
• 제55권3호
• /
• pp.236-242
• /
• 2018

Damage due to ice collision is the most serious threat for the structural safety of ships operating in arctic region. Since such hull damages are usually caused by the collision of floating ice at excessive voyage speed of ships, the authorities responsible for the shipping at arctic sea are required to provide the speed limit for safe voyage, so-called safe speed. In countries near arctic ocean, such as Canada and Russia, empirical methods to determine the safe speed of ships based on their long experience of arctic voyage have been established and applied them in the real arctic navigation. However, in Korea, it is not easy to accumulate the arctic voyage experience and related technical database, so it seems to be a realistic approach to adopt a safe voyage speed estimating method in arctic sea based on the ice collision simulation technology using the nonlinear finite element analysis. The aim of this study is to develop a technique for estimating the safe voyage speed of vessels operating at arctic sea through the ice collision analysis, In order to achieve this goal, the standard procedure of the ice collision analysis is dealt with and example analysis was carried out and the results were considered. To investigate the validity of developed method, POLARIS system proposed by IMO was studied for comparison.

• Ocean Systems Engineering
• /
• 제9권4호
• /
• pp.369-390
• /
• 2019

Herein, we present numerical simulation based model to study the use of a 'Tuned Mass Damper (TMD)' - particularly spring mass systems - to control the displacements at the deck level under seismic and ice loads for an offshore jacket structure. Jacket is a fixed structure and seismic loads can cause it to vibrate in the horizontal directions. These motions can disintegrate the structure and lead to potential failures causing extensive damage including environmental hazards and risking the lives of workers on the jacket. Hence, it is important to control the motion of jacket because of earthquake and ice loads. We analyze an offshore jacket platform with a tuned mass damper under the earthquake and ice loads and explore different locations to place the TMD. Through, selected parametric variations a suitable location for the placement of TMD for the jacket structure is arrived and this implies the design applicability of the present research. The ANSYS^*TM mechanical APDL software has been used for the numerical modeling and analysis of the jacket structure. The dynamic response is obtained under dynamic seismic and ice loadings, and the model is attached with a TMD. Parameters of the TMD are studied based on the 'Principle of Absorption (PoA)' to reduce the displacement of the deck level in the jacket structure. Finally, in our results, the proper mass ratio and damping ratios are obtained for various earthquake and ice loads.

• 설비공학논문집
• /
• 제17권2호
• /
• pp.156-164
• /
• 2005

A comparative analysis of an ice storage system has been performed on the operation cost for the four control strategies, i.e., chiller priority and chiller downstream, chiller priority and chiller upstream, storage priority and chiller upstream, storage priority and chiller downstream. Main components of the ice storage system are an ice-on-coil storage tank and a screw compressor chiller. With the simulation program, the operation cost has been evaluated from the economics of an ice storage system. It is found that the operation cost of the ice storage system is strongly dependent on the control strategy, i.e., chiller priority or storage priority, but less affected by the arrangement method, i.e., chiller upstream or chiller downstream. In case of the maximum load day, the control strategy with chiller priority and chiller upstream is supposed to obtain the reduction of operation cost. However, it is found that the control strategy with storage priority and chiller downstream is the best economical operation for most summer seasons except the maximum load day.

• 대한조선학회논문집
• /
• 제51권2호
• /
• pp.107-113
• /
• 2014

The icebreaking research vessel, ARAON had her second ice trial in the Arctic Sea from 16th July to 12th August 2010. During the voyage, the local ice loads acting on the bow of port side were measured from 14 strain gauges. The measurements were also carried out in ice waters with various ice concentration ratio as well as the icebreaking performance tests. In this study, the ice loads measured during the 'general' operation in ice waters were analyzed. As a first step, the relationship between the location of strain gauges and the ice loads were investigated, and then the possibility for observation of higher ice loads was estimated based on the probability density function. The relationship between the ship speed and the ice load was also investigated. 718 peak stresses data higher than 20 MPa obtained from strain gauges array attached in longitudinally and vertically was analyzed. In general, the ice load increases as the ship speed increases in the low ship speed range, and ice load decreases as the ship speed is greater than a certain speed.

• 대한기계학회논문집B
• /
• 제20권10호
• /
• pp.3313-3321
• /
• 1996

A fundamental study in cooling and solidification process focused on ice storage was performed, including the interesting phenomena of density inversion, supercooling and dendritic ice. A numerical study was performed for natural convection and ice formation in the cooling and freezing processes with supercooling in a space between double cylinders. When water was cooled under the freezing point by a cooling wall in a cavity, solidification was not started at once, but a subcooled region was formed near the wall. Especially, when the cooling rate was low, subcooled region extended to a wide area. However, after a few minutes, supercooling is released by some triggers. Dendritic ice is suddenly formed within a subcooled region, and a dense ice layer begins to be developed from the cooling wall. Due to the difficulties, most previous studies on solidification process with numerical methods had not treated the supercooling phenomena, i.e. the case considering only the growth of dense ice. In this study, natural convection and ice formation considering existence of supercooling and dendritic ice were analyzed numerically with using finite difference method and boundary fixing method. The results of numerical analysis were well compared with the experimental results.

• 한국해양공학회지
• /
• 제32권3호
• /
• pp.177-183
• /
• 2018

This study simulated ice load and the motion response of a moored semi-submersible rig in pack-ice conditions using a finite element method. Ice flows of random size and shape were modeled, and interactions for ice-sea, ice-structure, ice-ice were simulated using a simplified method. Parameters for the simplified method such as drag force coefficient and the pressure-penetration relation were obtained based on the result of detailed analysis using the coupled Eulerian-Lagrangian method. The mooring lines were modeled by spring elements based on their stiffness. As a result of the simulation over 1,400 seconds, the force and motion response of the rig were obtained and validated using discrete elements and compared with the results found by the Krylov State Research Centre.

• 한국산학기술학회:학술대회논문집
• /
• 한국산학기술학회 2002년도 추계학술발표논문집
• /
• pp.253-257
• /
• 2002

본 논문에서는 아이스크림용 아이스 콘에서 콘 부분을 만들기 위한 금형의 제작시 필요한 구조적 안정성을 평가할 수 있는 유동해석을 수행하였다. 유동해석을 수행하기 위하여 상용 유한요소해석 코드인 ANSYS클 활용하였으며 내압조건, 경계조건, 구속조건 등을 고려하여 아이스 콘 금형내부의 유동 흐름을 압력조건의 변화에 따라 구하였다.

• 설비공학논문집
• /
• 제12권4호
• /
• pp.337-344
• /
• 2000

The present study describes a one-dimensional modeling of encapsulated ice storage tanks. The thermal transmittance of capsules in this model uses the results from the Arnold's experimental $study^{(2-3)}$.In this model, ice storage tank is partitioned by several control volumes for the analysis, each having same number of capsules. The model is validated by the comparison of the measured data from an ice storage tank installed at a building with the capacity of 1200 ton-hrs and the simulated results with the same inlet brine temperature conditions into the tank.