• Journal of the Korean Society of Visualization
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• v.19 no.1
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• pp.62-67
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• 2021

Selective catalytic reduction(SCR) is an exhaust gas reduction device to remove nitro oxides (NOx). SCR operation of ship can be controlled through valves for minimizing economic loss from SCR. Valve in SCR-high pressure (HP) system is directly connected to engine exhaust and operates in high temperature and high pressure. Long-term thermal deformation induced by engine heat weakens the sealing of the valve, which can lead to unexpected failures during ship sailing. In order to prevent the unexpected failures due to long-term valve thermal deformation, a failure prediction system using autoregressive integrated moving average (ARIMA) was proposed. Based on the heating experiment, virtual data mimicking temperature range around the SCR-HP valve were produced. By detecting abnormal temperature rise and fall based on the short-term ARIMA prediction, an algorithm determines whether present temperature data is required for failure prediction. The signal processed by the data collection algorithm was interpolated for the failure prediction. By comparing mean average error (MAE) and root mean square error (RMSE), ARIMA model and suitable prediction instant were determined.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.141-148
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• 2017

This researcher selected basic variable to investigate the effective relations of establishment and management of resting facility on reduction of constructional disasters and safety accidents and improvement of working efficiency for construction workers. Based on the measured variables, this researcher investigated phenomenon, recognition and satisfaction for using and demanding resting facility by long-term construction in construction site for workers of huge construction site in Seoul, conducted survey of total 219 questionnaires so as to grasp implications of workers' resting facility demanded in long-term huge construction site and effects on reduction of disasters and conducted structural equation analysis. As a result, resting faciity factor, management factor, and hygienic service factor were significant and resting and food factors were not significant. Therefore, it's expected to reduce personal disaster by improving quality of constructional resting facility, hygienic service, and resting facility management and especially, resting facility management factor makes lots of effects on prevention of personal disasters, so it was a strongly main factor. By suggesting the guideline of establishment and management service of proper resting facility through this research, positive recognition and constructional disaster reduction can be expected in construction site.

• Korean Journal of Mathematics
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• v.18 no.3
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• pp.323-334
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• 2010

We give a theorem for the existence of at least three solutions for the fourth order elliptic boundary value problem with the square growth variable coefficient nonlinear term. We use the variational reduction method and the critical point theory for the associated functional on the finite dimensional subspace to prove our main result. We investigate the shape of the graph of the associated functional on the finite dimensional subspace, (P.S.) condition and the behavior of the associated functional in the neighborhood of the origin on the finite dimensional reduction subspace.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1567-1573
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• 2017

The k-nearest neighbor (k-NN) algorithm is one of the most widely used benchmark algorithm in classification. Nowadays it has been further applied to predict time series. However, one of the main concerns of the algorithm applied on short-term electricity load forecasting is high computational burden. In the paper, we propose an approach of dimension reduction that follows the principles of highlighting the temperature effect on electricity load data series. The results show the proposed approach is able to reduce the dimension of the data around 30%. Moreover, with temperature effect highlighting, the approach will contribute to finding similar days accurately, and then raise forecasting accuracy slightly.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.46 no.2
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• pp.87-98
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• 2020

The aim of this study was to determine the efficacy of oral splints in reducing the intensity of pain in patients with temporomandibular joint dysfunction in both short and long-term treatment durations. Electronic databases, Cochrane Library, MEDLINE via PubMed, Web of Science, Egyptian Knowledge Bank, and EMBASE were searched for randomized controlled trials comparing different types of splints to non-occluding splints, behavioral therapy, pharmacotherapy, counseling, and no treatment. The risk of bias was assessed by using Cochrane risk of bias recommendations. Fixed and random effects were used to summarize the outcomes. The effect estimates were expressed as standardized mean differences (SMD) or risk ratios with a 95% confidence interval (CI). Subgroup analyses were carried out according to the treatment duration. Twenty-two studies met the inclusion criteria. A meta-analysis of short-term studies up to three months revealed no significant difference between the study groups. However, long-term studies exhibited a significant difference in pain reduction in favor of the control group. Total analysis revealed that the control group resulted in significant pain reduction (SMD 0.14, 95% CI 0.05-0.23, P=0.002, I²=0%). Oral splints are not effective in reducing pain intensity or improving function in patients with temporomandibular joint dysfunction.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.75-79
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• 2023

The International Maritime Organization (IMO) Marine Environmental Protection Committee (MEPC) may adopt actions after completing impact assessments and reviewing results in accordance with the original strategy and impact assessment procedure (MEPC.1/Circ.885). The assessment of the impact of greenhouse gas (GHG) reduction measures is an important step in determining whether to implement GHG regulations. This study identifies and proposes improvements in the impact assessment procedure for future mid- and long-term measures. Improvements for future measures should start with a review of "the procedure for assessing impacts on states of candidate measures" and "the actual process of the comprehensive impact assessment for short-term measures in 2021." The procedural improvements were largely derived from the order and period of task performance, the clear definition of terms, and the review of task results through lessons learned, analysis, and expert workshops. The impact assessment of future mid- and long-term measures should be procedurally improved to ensure uniformity and consistency, which will provide objective results for Member States and industries to help smooth the adoption of measures.

• Journal of the Korea Concrete Institute
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• v.23 no.6
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• pp.817-826
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• 2011

Concrete using eco-cement has a problem with long-term strength development. However, currently, a long-term strength development mechanism is not confirmed, resulting in a lack of application of eco-cement in construction fields. In this study, the curing humidity influence on development in long-term strength of concrete using eco-cement and the relationship between strength and pore structure were examined. The results showed that wet cured eco-cement with a high water/cement ratio showed serious long-term strength reduction due to non-reduction of pore volume (pore size over 10 nm) in mortar caste with eco-cement. Also, the study results on improvement of long-term strength of eco-cement by partial replacement with ordinary portland cement and finely-ground fly ash showed that both of these alternatives improved long-term strength of concrete caste with eco-cement due to gradual refinement of their micro-structure.

• Journal of Korean Foot and Ankle Society
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• v.11 no.1
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• pp.91-96
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• 2007

Purpose: To evaluate the clinical results and determine appropriate methods of surgical treatment about type II talar neck fracture. Materials and Methods: Among nineteen patients who received surgical treatment for type II talar neck fracture from May 2000 to May 2005. Fourteen patients with a follow-up period of more than 1 year were divided into two groups. Six patients reduced by closed reduction (Group A) with screw fixation and eight patients reduced by open reduction with screw fixation. We analyzed preoperative, postoperative and follow-up simple radiographs and reviewed patient hospital records retrospectively. Clinical results were evaluated by Hawkins scoring system. We analyzed pain, limp, range of motion of ankle and subtalar joint. Results: Five patients (83.3%) in group A and seven patients (87.7%) in group B had excellent and good clinical results. There were no complications including avascular necrosis, delayed union, nonunion. Conclusion: Closed reduction with screw fixation of talar neck fracture shows correct reduction and satisfactory results. But because of short term period of follow-up, we need long term results.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.225-226
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• 2009

Day by day, concrete buildings and structure became high-rising and magnificently vast scheduled, as contributed from the development of improved equipments that suitable to specific construction works and high qualitied Material, the durability of the concrete was highly improved. The temporary elastic reduction occur at vertical members such as walls and columns under vertical loads. Specially, inelastic reduction such as creep and shrinkage occur long termly with elastic one in case of reinforced concrete members. Generally, creep and shrinkage depend on time and this is affected by concrete strength, concrete type, member size, steel ratio, and relative humidity. And elastic reduction rely on time, too because concrete is loaded before revelation of perfect strength in terms of construction conditions. So, tests on mechanical properties of concrete certainly need in order to apply to construction by forecasting an amount of reduction caused by the complex factors. Therefore, in this study the tests on creep, shrinkage are carried out to offer basic data for predicting an amount of long-term Properties at the concrete columns of an object structure, and results of the tests are described.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.196-203
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• 2008

Durability of geosynthetics for soil reinforcement is accounted for creep and creep rupture, installation damage and weathering, chemical and biological degradation. Among these, the long-term creep properties have been considered as the most important factors which are directly related to the failure of geosynthetic-reinforced soil(GRS). However, the creep test methods and strain limits are too various to compare the test results with each other. The most widely used test methods are conventional creep test, time-temperature superposition and stepped isothermal method as accelerated creep tests. Recently developed design guidelines recommend that creep-rupture curve be used to determine the creep reduction factor($RF_{CR}$) which is a conservative approach. In this study, the different creep test methods were compared and the creep reduction factors were estimated at different creep strain limits of 10% of total creep strain and creep rupture. In order to minimize the impact of creep strain to the GRS structures, the various creep reduction factors using different creep test methods should be investigated and then the most appropriated one should be selected for incorporating into the design.