• 대한조선학회논문집
• /
• 제45권5호
• /
• pp.562-568
• /
• 2008

In this study, the target FSICR class is 1A whose target thickness of the brash ice is 46 mm in model scale. Normally ice floes for brash ice do not exceed 2 m in full scale, so the model ice sheet was cut by about 10 cm by 10 cm using hand saws. Since the target thickness of brash ice is 46 mm, 46 mm ice sheet makes one layer brash ice. For 23 mm thickness ice sheet, two layers should be accumulated to reach 46mm brash ice thickness. For 15mm thickness ice sheet, three layers need to be accumulated as the same as those in 23 mm ice sheet. New methodology to produce a brash ice was proposed. The results showed that it would be important to use multi-layer rather than single layer possibly because of significant thrust deduction from the propeller-ice interaction in the present ice condition (FSICR 1A).

• 대한기계학회논문집B
• /
• 제24권11호
• /
• pp.1497-1505
• /
• 2000

A numerical study is made on the ice-formation for a laminar flow in a curved channel. When the water flows through the curved channel with the walls specified below the freezing temperature, the ice layer has been formed on the curved surface, different from that of a straight channel. The fluctuation of ice layer has been predicted, considering the variation of velocity and temperature near the curved portion of channel. The study also takes into account the interaction existing between the laminar flow and the curved channel. In the solution strategy, the present study is substantially different from the existing works in that the complete set of governing equations in both the solid and liquid regions are resolved. The results from this study have been mainly presented, focusing on the variation of ice layer close to the curved portion. Numerical results have been obtained parametrically by varying the curved angle and the radius of curvature of channel, in addition to the variation of Reynolds numbers and wall temperatures of channel. The results show that the curved shape of channel has the great effect on the thickness of the solidification layer. The wave of ice layer thickness appears in the vicinity of curved portion. This behavior of ice layer has been amplified as is the increasing of curved angle and the radius of curvature of channel. In addition, the ice layer becomes thin as Reynolds numbers in increasing. And also, as the wall temperature of channel increases, the width of channel becomes to be shrunk due to the growth of ice layers in the upper and lower wall of channel.

• 대한기계학회논문집B
• /
• 제21권11호
• /
• pp.1552-1561
• /
• 1997

In this numerical study, it is investigated for the ice-formation phenomena for water flow in a concentric tube. The freezing layers of ice in both the inner and outer wall of a concentric tube are simultaneously considered. In the solution strategy, the complete set of governing equations in both the solid and liquid regions are resolved. Numerical results are obtained by varying the inner/outer wall temperatures and Reynolds number. The results show that the inner/outer wall temperatures have the great effect on the thickness of the solidification layer thereof. The shapes of ice layer in both the inner and outer wall can be expressed as a function of inverse Graetz number. As the wall temperature in inner or outer tube decreases, the heat transfer coefficients in both inner and outer ice layer surfaces increase absolutely.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2004년도 춘계 학술발표회 논문집
• /
• pp.219-224
• /
• 2004

The present study was to investigate the heat transfer enhancement effect of coil wire fins in an ice storage system. For the two cases of tubes with internal brine flows, a finned tube with coil wires on its outer surface and a smooth tube, the rates of ice layer were tested and compared for both the icing processes. The coil fins were made of a stainless steel wire with a dia. of 2.0(mm), and the coil had an outer dia. of 10(mm) and a helix angle of 60($^{\circ}$). The experimental results showed that the coil fins could substantially reduce the thermal resistance of the ice layer, and enhance the heat flow rates between the water in the storage tank and the brine. The ice storing time was found to be shortened by 13(%) for the coil fins to get the same amount of ice layer that was built on the smooth tube wall for 10 hours of operation when the same thermal conditions were provided.

• Journal of Advanced Marine Engineering and Technology
• /
• 제19권1호
• /
• pp.36-44
• /
• 1995

Melting characteristics of unrestrained liquid ice in a rectangular vessel with heated top wall were investigated experimentally. The liquid ice, a mixture of ice particles and ethylene-glycol aqueous solution, was adopted as a testing material. During the melting process the liquid ice was drawn by buoyancy to the heated top wall of the rectangular vessel where close-contact melting occured. The melting behavior and melting rate of the liquid ice as well as local/mean heat-transfer coefficient at the heated top wall were observed and measured under a variety of conditions of heat flux and various initial concentration of the aqueous binary solution. It was found that the heat transfer of the heated top wall is remarkably promoted by the close-contact melting, and that the dendritic frozen layer at the lower interface of the liquid ice is formed. Photographic evidence demonstrated that plumes containing solute-rich liquid issued from isolated chimneys within the liquid ice layer where segregation of interstitial channel took place.

• 대한조선학회논문집
• /
• 제49권2호
• /
• pp.189-195
• /
• 2012

The ice trials of the first Korean icebreaking research vessel "ARAON" were performed at the Arctic Ocean in July-August 2010. The sea ice concentrations of Arctic Ocean were 4/10 to 10/10 and the range of sea ice thickness was roughly 1.0 to 3.5m. In this research, sea ice thickness characteristics at the old ice floes were determined from results of drill hole and apparent conductivity measurements. Especially we measured apparent conductivity using an electromagnetic induction instrument (EM31-MK2) and estimated the sea ice thickness through the empirical equation from Cold Regions Research & Engineering Laboratory, CRREL. The results of estimated sea ice thickness were compared to drill hole measurement results and then, we suggest the new empirical equation to estimate sea ice thickness of single layer type sea ice during the summer season of Arctic Ocean by curve fitting approach to these data.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
• /
• pp.263-263
• /
• 2013

This work examines the dynamic properties of ice surfaces in vacuum for the temperature range of 140~180 K, which extends over the onset temperatures for ice sublimation and the phase transition from amorphous to crystallization ice. In particular, the study focuses on the transport processes of excess protons and chloride ions in ice and their segregative behavior to the ice surface. These phenomena were studied by conducting experiments with a relatively thick (~100 BL) ice film constructed with a bottom $H_2O$ layer and an upper $D_2O$ layer, with excess hydronium and chloride ions trapped at the $H_2O$/$D_2O$ interface as they were generated by the ionization of hydrogen chloride. The migration of protons, chloride ions, and water molecules to the ice film surface and their H/D exchange reactions were measured as a function of temperature using the methods of low energy sputtering (LES) and Cs+ reactive ion scattering (RIS). Temperature programmed desorption (TPD) experiments monitored the desorption of water and hydrogen chloride from the surface. Our observations indicated that both hydronium and chloride ions migrated from the interfacial layer to segregate to the surface at high temperature. Hydrogen chloride gas desorbs via recombination reaction of hydronium and chloride ions floating on the surface. Surface segregation of these species is driven by thermodynamic potential gradient present near the ice surface, whereas in the bulk, their transport is facilitated by thermal diffusion process. The finding suggests that chlorine activation reactions of hydrogen chloride for polar stratospheric ice particles occur at the surface of ice within a depth of at most a few molecular layers, rather than in the bulk phase.

• 복식문화연구
• /
• 제21권2호
• /
• pp.261-271
• /
• 2013

This study aimed to identify professional climbers'demand for movement functionality in pants worn for rock climbing and ice climbing. Data were collected through in-depth interviews with 12 professional climbers using a semi-constructed questionnaire. The respondents were instructor-level experts whose climbing ability ranged from 5.9 to 5.14 on the Yosemite Decimal System rating scale. The research findings were as follows. Experts wore different climbing pants depending on the type of climbing. For example, they mostly wore high-stretch, second layer pants for rock climbing, while layering first layer, second layer, and third layer pants for ice climbing. There were gender differences regarding the parts of the body in which climbers reported the most discomfort when wearing climbing pants; male climbers most commonly responded 'knees', 'inner thighs' and 'hips' while their female counterparts most commonly responded 'inner thighs', 'exposed back and waist' and 'hips' in that order. Differences were found between rock climbing and ice climbing in terms of wear and tear on pants, preferred fabric properties, and length of pants. Wear and tear was found mainly on the hips and knees of rock climbing pants and on the inner lower hem of ice climbing pants. Listed in the order of preference, the most preferred fabric properties were elasticity, light weight, and durability for rock climbing pants and elasticity, insulation, and protection against water and wind for ice climbing pants. Regarding the length of rock climbing pants, respondents preferred ankle-length pants and cropped pants that did not cover the feet. For ice climbing pants, respondents favored heel-length pants that prevented pieces of ice from entering the clothing. Men showed a high level of preference for ergonomically cut climbing pants. Respondents said the waistband on climbing pants should be simplified so as not to adversely affect climbing maneuvers.

• Journal of Advanced Marine Engineering and Technology
• /
• 제35권4호
• /
• pp.421-428
• /
• 2011

최근 지구 온난화와 더불어 급격한 기후 변화 등으로 여름철 주간 냉방 수요가 급격히 증가하여 이에 따른 전력 수요량이 증가하고 있다. 또한 주간 전력 피크로 인한 급격한 전력부하 상승은 전력 수급의 불균형을 가져 와 사회적 문제로 대두되고 있다. 이를 위해 개발된 축냉시스템은 전력사용량이 상대적으로 적은 심야시간에 냉열을 만들어 탱크에 저장해 두었다가 그것을 주간 냉방 전력 사용 피크시간에 이용함으로써, 냉동기의 용량이 작아지고 냉동기를 고효율로 운전할 수 있으며, 갑작스런 부하 증가에 적절히 대응할 수 있는 등 여러 가지 장점을 갖고 있다. 이로 인하여 주간전력 피크를 줄여주는 효과를 가진다. 축냉시스템 중 하나인 슬러리아이스형은 슬러리아이스가 과냉되지 않은 작은 입자형태를 갖고 있어 해빙특성이 뛰어나므로 부하변동에 빠르게 반응할 수 있으며, 그 저장과 재생 및 수송 분야에서 그 장점과 기능이 입증되었다. 본 실험에서는 슬러리아이스 생성 효율을 높이기 위하여 역전유동층을 이용하였다. 이러한 역전유동층은 냉각관 표면에 얼음 부착이 심화되기 전에 얼음 입자를 분리시켜 수 내지 수십 미크론 단위(0.1~0.001 mm)의 슬러리아이스를 생성하도록 하였다.

• 한국항해항만학회지
• /
• 제37권2호
• /
• pp.129-135
• /
• 2013

동결농축폐수처리의 기술은 열역학적 효율이 높고 에너지 소비량이 작아 중소규모로 적합하며, 용수 재활용과 융해열의 냉열 재이용이 가능한 장점을 가지고 있다. 본 연구에서는 폐수 처리효율이 높은 동결농축폐수처리장치의 개발을 위해 수직원관 형태의 제빙관을 대상으로 염화나트륨수용액을 이용한 기초 실험을 통해 냉각면 온도, 기포 분사 방법에 따른 분리 성능을 확인 후 대표적 중금속인 Pb, Cr 수용액을 대상으로 냉각면 온도, 기포 직접 분사, 과냉각을 방지하기 위한 용질을 포함하지 않은 초기 빙층 두께의 영향에 따른 중금속 분리 성능을 실험 통해 확인하였다. 실험결과 두 수용액에서 모두 냉각면의 온도가 낮을수록 동결층의 성장속도가 빨라지고 용질의 분리효율이 저하되었다. 기포를 분사하는 방법 중에는 환모양의 노즐을 통해 동결계면에 직접 분사하는 방법이 원통벽면을 통해 간접 분사하는 것 보다 분리효율이 높게 나타났으며, 초기 빙층의 두께에 따른 실험에서는 1mm 보다는 5mm의 두께에서 분리효율이 더 우수한 것으로 나타났다.