• Special Issue of the Society of Naval Architects of Korea
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• 2006.09a
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• pp.40-45
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• 2006

For ships of ice class, finish Maritime Administration(FMA) requires brackets on intersections between longitudinal frames and the web frames within the ice-strengthened area. The main object of this paper is to verify ultimate load carrying capacity of longitudinal frame without brackets of engine room region of 74,100 DWT Product Oil Tanker. Comparative approach between proposed structures from builder (the proposed structure) and structures satisfying the Finnish-Swedish ice class rules (the rule structure) is used for the analysis.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.2
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• pp.80-87
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• 2020

As the Arctic sea ice decreases due to various reasons such as global warming, the demand for ships and offshore structures operating in the Arctic region is steadily increasing. In the case of sea ice, the anisotropy is caused by the uncertainty inside the material. For most of the research, nevertheless, estimating the ice load has been treated deterministically. With regard to this, in this paper, a four-point bending strength analysis of an ice specimen was attempted using a stochastic finite element method. First, spatial distribution of the material properties used in the yield criterion was assumed to be a multivariate Gaussian random field. After that, a direct method, which is a sort of stochastic finite element method, and a sensitivity method using the sensitivity of response for random variables were proposed for calculating the probabilistic distribution of ice specimen strength. A parametric study was conducted with different mean vectors and correlation lengths for each material property used in the above procedure. The calculation time was about ten seconds for the direct method and about three minutes for the sensitivity methods. As the cohesion and correlation length increased, the mean value of the critical load and the standard deviation increased. On the contrary, they decreased as the friction angle increased. Also, in all cases, the direct and sensitivity methods yielded very similar results.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.156-163
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• 2009

Statement of problem: Recently, there have been increased esthetic needs for posterior dental restorations. The failure of posterior dental ceramic restoration are possible not only by the characters of the component materials but also by the type of food. Purpose: The research aim was to compare the in vitro fracture resistance of simulated first molar crowns fabricated using 4 dental ceramic systems, full-porcelain-occlusal-surfaced PFG, half-porcelain-occlusal-surfaced PFG, Empress 2, Ice Zirkon and selected Korean foods. Material and methods: Eighty axisymmetric crowns of each system were fabricated to fit a preparation with 1.5- to 2.0-mm occlusal reduction. The center of the occlusal surface on each of 15 specimens per ceramic system was axially loaded to fracture in a Instron 4465, and the maximum load(N) was recorded. Afterwards, selected Korean foods specimens(boiled crab, boiled chicken with bone, boiled beef rib, dried squid, dried anchovy, round candy, walnut shell) were prepared. 15 specimens per each food were placed under the Instron and the maximum fracture loads for them were recorded. The 95% confidence intervals of the characteristic failure load were compared between dental ceramic systems and Korean foods. Afterwards, on the basis of previous results, 14Hz cyclic load was applied on the 4 systems of dental ceramic restorations in MTS. The reults were analyzed by analysis of variance and Post Hoc tests. Results: 95% confidence intervals for mean of fracture load 1. full porcelain occlusal surfaced PFG Crown: 2599.3 to 2809.1 N 2. half porcelain occlusal surfaced PFG Crown: 3689.4 to 3819.8 N 3. Ice Zirkon Crown: 1501.2 to 1867.9 N 4. Empress 2 Crown: 803.2 to 1188.5 N 5. boiled crab: 294.1 to 367.9 N 6. boiled chicken with bone: 357.1 to 408.6 N 7. boiled beef rib: 4077.7 to 4356.0 N 8. dried squid: 147.5 to 190.5 N 9. dried anchovy: 35.6 to 46.5 N 10. round candy: 1900.5 to 2615.8 N 11. walnut shell: 85.7 to 373.1 N under cyclic load(14Hz) in MTS, fracture load and masticatory cycles are: 1. full porcelain occlusal surfaced PFG Crown fractured at 95% confidence intervals of 4796.8-9321.2 cycles under 2224.8 N(round candy)load, no fracture under smaller loads. 2. half porcelain occlusal surfaced PFG Crown fractured at 95% confidence intervals of 881705.1-1143565.7 cycles under 2224.8 N(round candy). no fracture under smaller loads. 3. Ice Zirkon Crown fractured at 95% confidence intervlas of 979993.0-1145773.4 cycles under 382.9 N(boiled chicken with bone). no fracture under smaller loads. 4. Empress 2 Crown fractured at 95% confidence intervals of 564.1-954.7 cycles under 382.9 N(boiled chicken with bone). no fracture under smaller loads. Conclusion: There was a significant difference in fracture resistance between experimental groups. Under single load, Korean foods than can cause fracture to the dental ceramic restorations are boiled beef rib and round candy. Even if there is no fracture under single load, cyclic dynamic load can fracture dental posterior ceramic crowns. Experimental data with 14 Hz dynamic cyclic load are obtained as follows. 1. PFG crown(full porcelain occlusion) was failed after mean 0.03 years under fracture load for round candy(2224.8 N). 2. PFG crown(half porcelain occlusion) was failed after mean 4.1 years under fracture load for round candy(2224.8 N). 3. Ice Zirkon crown was failed after mean 4.3 years under fracture load for boiled chicken with bone(382.9 N). 4. Empress 2 crown was failed after mean 0.003 years under fracture load for boiled chicken with bone(382.9 N).

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1061-1064
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• 2009

The objective of this study is to find the optimal operational planning of the hybrid cooling system, which is combined by ice storage system and the absorption chiller. The optimization technique used in this study is dynamic programming. The objective function is summed cost during a day including charge and discharge periods of ice storage system and operation time of absorption chiller. Assuming that initially ice storage tank is stored fully and the cooling load is perfectly predicted for the operational planning. This method provides the most efficient and economic combination of equipment operational planning for cooling with respect to energy consumption cost.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.04a
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• pp.69-74
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• 2000

This paper describes an operation strategy of ice storage systems for energy saving during building cooling. In this study, chiller is assumed not having function of part load control. Thus, it is needed to adopt on-off control with the objective function of summed energy consumption for minimum energy consumption. A conventional control strategy compared with the chiller-on-off control is chiller-priority control. in this control chiller operates as its full capacity and ice storage meets the rest of the cooling load.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.369-376
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• 1988

Among several methods to solve the unbalanced electric power load, the Ice Storage System (ISS) for the air conditioning is relatively easy to realize and gives big effect on balancing the electric power load. The goals of this study are to develop the practical ISS for the air conditioning through the design, manufacturing and performance test of the experimental ISS (size $0.335m^3$, cold storage capacity 14200 kcal, IPF 0.4). Thermal fluid motion inside the ice storage tank during cooling storage and cooling release are studied. The data are analyzed by the dispersion analysis and optimal design conditions are derived from the result.

• Journal of Advanced Marine Engineering and Technology
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• v.15 no.5
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• pp.38-46
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• 1991

In the design of an electric power plant, the capacity to meet the peak load demand is one of the important factors to be considered. This peak load usually occurs when the most of the cooling air-conditioning systems are being operated during daytime in summer season. Therefore, it is necessary to construct an additional electric power plant and to develop the new air-conditioning system for relieving the peak load. This paper analysed the performance characteristics of this experimental regenerative ice energy system by means of a bundle of the heat-pipes. And the result of this analysis was applied to the simulation of an air-conditioning system model. Also, an operation program of moisture air was made according to air load and in order to computerize the air-conditioning system a CAD program was developed by the properties of moisture air.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.11
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• pp.1028-1034
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• 2004

Recently, the ice storage system using ice slurry has been used increasingly since it has been introduced where the rapid cooling load change is required. Because it overcomes a decrease of the melting performance and an increase of the thermal resistance on the ice layer in static ice thermal storage system. This study is performed to understand the effects of transporting ice slurry through horizontal, vertical and inclined tubes ($30^{\circ},\;45^{\circ}$). It used propylene glycol-water solution and ice particles (diameter of about 2 mm) in this experiment. The experiments were carried out under various conditions, with concentration of water solution ranging from 0 to $20wt\%$, and velocity of water solution at the entry ranging from 1.5 to 2.5 m/s. The results were as follows: Regarding the angle of inclined tube, the highest pressure loss was measured for vertical tube and the pressure loss for $45^{\circ},\;30^{\circ}$, horizontal straight tubes were lower successively. The lowest pressure loss in these tubes was measured at velocity of $2.0{\sim}2.5m/s$ and concentration of $10wt\%$. The outlet IPF was likewise stable in these ranges.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.4
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• pp.350-357
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• 2002

Optimal control algorithms for the full storage ice cooling system were developed by using a dynamic simulation program. Control algorithms for the storage charging mode were developed for the chiller outlet temperature setpoint control and the chiller capacity control. Control algorithms for the storage discharging mode were developed for the proper mode selection, the storage-only mode control, and the storage-priority chiller-shared mode control. Two different cases of the expected outdoor air temperature profile and the expected cooling load profile were used to analyze the effectiveness of these algorithms. Simulation results show the energy savings and the satisfactory controls of the ice storage system. Therefore, control algorithms developed for this study may effectively be used for the improved control of the ice storage cooling system.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.12
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• pp.1204-1209
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• 2005

In-situ measurement was made to evaluate chiller performance and thermal storage density of an ice thermal storage system. The system belonged to a big hotel and the measurement was conducted during late October. Owing to very small cooling load, the data logging was possible for a single thermal storage cycle. However, operation history of the chiller showed a relatively good spectrum of data for performance evaluation. COP and thermal storage density were calculated. The COP at full load was about 4.07, which was lower than $4.8\~6.4$ of new chillers. The measured storage density was about $10.9RT-h/m^3\;(=152MJ/m^3)$, which also was lower than a criterion of normal performance $(above\;13.0RT-h/m^3\;or\;181MJ/m^3)$. The study result provides technical basis for quantitative ESCO business scenario.