• 과학교육연구지
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• 제44권2호
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• pp.259-272
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• 2020

This study aims at investigating the effects of collective promotion on the attainment of literacy, numeracy, and essential life skills by primary school pupils and also to find out if the policy of collective promotion meets its objective of minimization of wastage in basic education. The study used written tests for pupils in the final class (Level II, class 6) to collect data in some selected English-speaking primary schools in Meme Division of Cameroon. Descriptive statistics and a one way ANOVA were used for analyzing data. The results revealed that the policy of collective promotion negatively affects the attainment of literacy, numeracy, and essential life skills of pupils in Kumba, Meme Division. Teachers who assisted in the study through personal communication with the researcher argued that collective promotion in basic education does not achieve its objective of minimizing wastage of educational resources; neither does it positively improve the literacy, numeracy, and essential life skills of pupils. This study recommends that the policy of collective promotion can be revisited and that focus be placed not only on minimizing wastage of resources but also on investing on quality education system so as to equip the would-be leaders of tomorrow with skills, knowledge, and attitudes which will make them functional and responsible citizens in their society.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.700-711
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• 2015

Sodium-cooled fast breeder reactors use liquid sodium as a moderator and coolant to transfer heat from the reactor core. The main hazard associated with sodium is its rapid reaction with water. Sodium-water reaction (SWR) takes place when water or vapor leak into the sodium side through a crack on a heat-transfer tube in a steam generator. If the SWR continues for some time, the SWR will damage the surface of the defective area, causing it to enlarge. This self-enlargement of the crack is called "self-wastage phenomena." A stepwise numerical evaluation model of the self-wastage phenomena was devised using a computational code of multicomponent multiphase flow involving a sodium-water chemical reaction: sodiumwater reaction analysis physics of interdisciplinary multiphase flow (SERAPHIM). The temperature of gas mixture and the concentration of NaOH at the surface of the tube wall are obtained by a numerical calculation using SERAPHIM. Averaged thermophysical properties are used to assess the local wastage depth at the tube surface. By reflecting the wastage depth to the computational grid, the self-wastage phenomena are evaluated. A two-dimensional benchmark analysis of an SWAT (Sodium-Water reAction Test rig) experiment is carried out to evaluate the feasibility of the numerical model. Numerical results show that the geometry and scale of enlarged cracks show good agreement with the experimental result. Enlarged cracks appear to taper inward to a significantly smaller opening on the inside of the tube wall. The enlarged outer diameter of the crack is 4.72 mm, which shows good agreement with the experimental data (4.96 mm).

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.165-177
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• 2019

This paper considers corrosion wastage of two ship hull structure members as a part of investigated fuel oil tanks of 25 aging bulk carriers. Taking into account that many factors which influence corrosion wastage of ship hull structures are of uncertain nature, the related corrosion rate ($c_1$) is considered here as a real-valued continuous distribution, assuming that the corrosion wastage starts after 5, 6 or 7 years. In all considered cases, by using available data and applying three basic statistical tests, it is established that between two-parameter continuous distributions, normal, Weibull and logistic distributions are best fitted distributions for the mentioned corrosion rate ($c_1$). Note that the presented statistical, numerical and graphical results concerning two mentioned ship hull structure members allow to compare and discuss the corresponding probabilistic estimates for the corrosion rate ($c_1$).

• Structural Engineering and Mechanics
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• 제42권4호
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• pp.531-549
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• 2012

Numerous oil tanker losses have been reported and one of the possible causes of such casualties is caused by the structural failure of aging ship hulls in rough weather. In aging ships, corrosion and fatigue cracks are the two most important factors affecting structural safety and integrity. This research is about effect on hull girder ultimate strength behavior of double hull oil tanker according to corrosion after Part I: stiffened panel. Based on corrosion data of Part I (time-dependent corrosion wastage model and CSR corrosion model), when progressing corrosion of fourtypes of double hull oil tankers (VLCC, Suezmax, Aframax, and Panamax), the ultimate strength behavior of hull girder is compared and analyzed. In case of the ultimate strength behavior of hull girder, when occurring corrosion, the result under vertical and horizontal bending moment is analyzed. The effect of time-dependent corrosion wastage on the ultimate hull girder strength as well as the area, section modulus, and moment of inertia are also studied. The result of this research will be useful data to evaluate ultimate hull girder strength of corroded double hull oil tanker.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.657-666
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• 2020

A reliable and cost-effective technique for the development of corrosion damage model is introduced to predict nonlinear time-dependent corrosion wastage of steel structures. A detailed explanation on how to propose a generalised mathematical formulation of the corrosion model is investigated in this paper (Part I), and verification and application of the developed method are covered in the following paper (Part II) by adopting corrosion data of a ship's ballast tank structure. In this study, probabilistic approaches including statistical analysis were applied to select the best fit probability density function (PDF) for the measured corrosion data. The sub-parameters of selected PDF, e.g., the largest extreme value distribution consisting of scale, and shape parameters, can be formulated as a function of time using curve fitting method. The proposed technique to formulate the refined time-dependent corrosion wastage model (TDCWM) will be useful for engineers as it provides an easy and accurate prediction of the 1) starting time of corrosion, 2) remaining life of the structure, and 3) nonlinear corrosion damage amount over time. In addition, the obtained outcome can be utilised for the development of simplified engineering software shown in Appendix B.

• Journal of Computing Science and Engineering
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• 제5권4호
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• pp.324-330
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• 2011

To avoid collisions, IEEE 802.11 medium access control (MAC) uses predetermined inter-frame spaces and the random back-off process. However, the retransmission strategy of IEEE 802.11 MAC results in considerable time wastage. The hidden node problem is well known in wireless networks; it aggravates the consequences of time wastage for retransmission. Many collision prevention and recovery approaches have been proposed to solve the hidden node problem, but all of them have complex control overhead. In this paper, we propose a fast retransmission scheme as a recovery approach. The proposed scheme identifies collisions caused by hidden nodes and then allows retransmission without collision. Analysis and simulations show that the proposed scheme has greater throughput than request-to-send and clear-to-send (RTS/CTS) and a shorter average waiting time.

• International Journal of Computer Science & Network Security
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• 제23권3호
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• pp.81-93
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• 2023

The popularity of short-form video platforms like TikTok has increased recently. Short-form videos are significantly shorter than traditional videos, and viewers regularly switch between different types of content to watch. Therefore, a successful prefetching strategy is essential for this novel type of video. This study provides a resource-effective prefetching technique for streaming short-form videos. The suggested solution dynamically adjusts the quantity of prefetched video data based on user viewing habits and network traffic conditions. The results of the experiments demonstrate that, in comparison to baseline approaches, our method may reduce data waste by 21% to 83%, start-up latency by 50% to 99%, and the total time of Re-buffering by 90% to 99%.

• Journal of Nutrition and Health
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• 제35권3호
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• pp.394-401
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• 2002

The purpose of this study was to : (a) examine diabetic patients' sensory evaluation and food preferences, (b) analyze the portion sizes & plate wastes, (c) investigate the factors affecting plate wastes, and (d) determine the nutritional & mometary values of the plate wastes. A questionnaire for determining food preference and sensory evaluation was developed. Thirty-three diabetic patients who were hospitalized in Sanggye Paik hospital in Seoul were studied. Serving sizes and plate wastes were weighed by using an electric scale, and the CAN-Pro program was used to evaluate the nutritional value or the food consumed. The data were analyzed using the SAS package program for descriptive analysis, t-test, ANOVA, and the Pearson correlation. Using a five-point Likeu-type scale, the temperature s[ore ranged from 3.1 to 3.3 (1 : very poor, 5 : excellent), the preference store was 3.0-3.2 (1 : very dislike, 5:very like), the taste score was 2.9-3.2 (1 : very poor, 5 : excellent), and the amount of food served score was 2.8-3.0 (1 : too little, 5 : too much). Serving sizes were considered insufficient by patients because most of the DM diet was low in calories. Average plate waste for the DM diet was 26.2% of the total served, by weight, and was lower than that for patients consuming a normal diet, which was 30.3%, found in previous research. Those subjects who had been previously hospitalized and who wished to participate in a campaign for food waste reduction produced less plate waste than other groups (p<.05). Plate wastes of the DM diet were negatively correlated with taste, temperature, and preference, and were positively correlated with the amount served: however, these results were not statistically significant. It was found that diabetic patients consumed adequate levels of energy, protein, Ca, Fe, Vitamin B$_1$, Vitamin B$_2$, and niacin, but inadequate levels of Phosphorus, Vitamin A and Vitamin C. The plate wastes were calculated to be 26.2% of the total cost (￦ 3,489), which is ￦9l5. This represents a significant wastage of resources from the hospital. The results of this study could assist foodservice managers in both controlling food wastage, and improving the quality of hospital food services.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제3권5호
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• pp.444-460
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• 2009

In this paper, we propose an expanded patching technique in order to reduce the server network bandwidth requirements to support true VoD services in VoD Systems. Double Patching, which is a typical multicast technique, ensures that a long patching stream delivers not only essential video data for the current client but also extra video data for future clients. Since the extra data may include useless data, it results in server network bandwidth wastage. In order to prevent a server from transmitting useless data, the proposed patching technique uses a new kind of stream called a linking stream. A linking stream is transmitted to clients that have received short patching streams, and it plays a linking role between a patching stream and a regular stream. The linking stream enables a server to avoid transmitting unnecessary data delivered by a long patching stream in Double Patching, so the server never wastes its network bandwidth. Mathematical analysis shows that the proposed technique requires less server network bandwidth to support true VoD services than Double Patching. Moreover, simulation results show that it has better average service latency and client defection rate compared with Double Patching.

• 한국통신학회논문지
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• 제36권7B호
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• pp.848-857
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• 2011

무선통신 기반의 원격검침 시스템은 설치의 용이함, 설비공사 및 유지보수 비용절감, 다양한 검침시스템으로의 적용의 유연성, 그리고 네트워크 확장성의 용이함 등의 장점으로 인해 최근 다양한 원격검침분야에서 활발히 활용되고 있다. 하지만, 이같은 다수의 장점에도 불구하고, 멀티 홉 기반의 원격검침망에서는 매 검침데이타 획득시마다 과다한 양의 트래픽을 발생시킴으로써, 데이터 충돌과 간섭의 확률을 증대시키고, 불필요한 전송으로 인한 에너지 낭비와 함께 특정 노드들의 에너지만 급격하게 소모되는 에너지 불균형 현상을 야기하고 있다. 그리하여 본 논문에서는 멀티홉 기반의 무선 원격검침망에서 발생하는 트래픽의 양을 최소로 줄임으로써 검침망의 각 노드들의 에너지 보존은 물론 다양한 문제점들을 해결할 수 있는 효율적인 검침데이타 수집기법을 제안하고, 성능평가를 통해 제안하는 기법에 대한 성능의 우수성을 입증한다.