• Journal of the Korean Wood Science and Technology
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• 제31권4호
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• pp.24-30
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• 2003

본 연구에서는 합판 대체용도로서 고성능을 보유하는 대나무 Zephyr 보드의 제조기술을 확립하기 위한 기초조사로서 Zephyr의 제조방법을 달리하여 Zephyr를 제조한 후 각각의 Zephyr로 제조된 보드의 물성을 검토하였다. 제조된 보드는 KS F 3014와 KS F 3113에 준하여 성능평가를 하였으며 그 결과는 다음과 같다. 최종 롤러간극을 각각 1 mm, 1.5 mm, 2 mm로 달리하여 제조된 Zephyr 보드 중에서는 1.5 mm에서 제조된 Zephyr 보드가 휨성능(MOR, MOE)과 박리강도(IB)에서 가장 높은 강도를 보유하고 있었다. 또한, 2시간 자비한 후 1시간 상온수에 침지한 다음에 측정된 보드의 습윤시 휨성능(MOR, MOE) 역시 최종 롤러간극 1.5 mm에서 제조된 Zephyr 보드에서 가장 높은 잔존강도를 보유하고 있어 상태시와 거의 유사한 경향을 나타내고 있었다. 24시간 상온수에 침지한 후의 두께팽창율 시험에서 모든 보드가 KS A 3014의 기준인 12%보다 낮게 나타났으며 그중 롤러간극 1.5 mm Zephyr로 제조된 보드가 가장 낮은 값을 나타내어 치수안정성이 뛰어난 것으로 나타났다. 전처리에 따른 대나무 Zephyr 보드의 강도 성능은 무처리 생재상태로 제조된 보드가 다른 전처리(증해, 0.3%NaOH자비)를 한 Zephyr 보드보다 높은 강도를 보유하고 있었다. 따라서, 무처리 생재상태에서 최종롤러 간극 1.5 mm로 제조된 Zephyr sheet가 최적의 보드 제조조건임을 알 수 있었다.

• 한국식품과학회지
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• 제39권4호
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• pp.419-424
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• 2007

생 홍고추를 열수, 오존수, 과산화수소와 차아염소산나트륨으로 살균 처리하여 적정 살균조건을 선정하고 선정된 조건에서 살균한 홍고추를 $-70^{\circ}C$로 냉동하여 $-30^{\circ}C$에서 30일 동안 저장한 후 품질변화를 측정하였다. $95^{\circ}C$에서 4분간 열수 처리하였을 때 E. coli와 coliform이 음성을 나타내었으며, 오존수 처리는 0.5 ppm에서 6분간 살균 처리하였을 때, 과산화수소는 2% 용액으로 12분간 살균처리로 음성을 나타냈다. 차아염소산나트륨 처리는 3% 용액으로 4분간 처리하였을 때 음성을 나타내었다. 선정된 각 최적조건에서 살균 처리하여 냉동저장 후 품질변화를 측정한 결과, 드립발생은 열수처리 시료가 15%로 가장 높았다. Ascorbic acid 함량은 오존수 처리 시료를 제외한 다른 처리구들은 대조구의 40%에도 미치지 못하는 함량을 나타내었으며, carotenoids 함량은 오존수 처리 시료가 124.16-182.87 mg%로 가장 적은 손실을 보였다. 관능검사 결과 오존수 처리 시료를 제외한 다른 처리구들은 내피의 탈색이 심하게 일어나고, 특히 열수처리의 경우 살균 처리에 의해 과육이 물러져서 외관이 심하게 손상되어 대조구와 유의적 차이를 나타내었다(p < 0.05). 따라서 시험한 살균방법 중에서 오존수처리가 가장 우수한 품질의 살균 생 홍고추를 생산하는데 적합한 방법으로 평가되었다.

• 한국주조공학회지
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• 제17권6호
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• pp.560-568
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• 1997

The dissolution behavior of secondary solidification phases in squeeze cast Al-3.9wt%Cu-1.5wt%Si-1.0wt%Mg has been studied using a combination of optical microscope, image analyzer, scanning electron microscope(SEM), energy dispersive spectrometer(EDS), X-ray diffractometer(XRD) and differential thermal analyzer (DTA). Special emphasis was placed on the investigation of the effects of the nonequilibrium heat treatment on the dissolution of the second solidification phases. Ascast microstructure consisted of primary solidification product of ${\alpha}-Al$ and secondary solidification products of $Al_2Cu$, $Mg_2Si$ and $Al_2CuMg$. Equilibrium and non-equilibrium solution treatments were carried out at the temperatures of $495^{\circ}C$, $502^{\circ}C$ and $515^{\circ}C$ for 3 to 5 hours. The amount of the dissolved secondary phases increased with increasing solution treatment temperature, for example, area fractions of $Al_2Cu$, $Mg_2Si$ and $Al_2CuMg$ were approximately 0%, 1.6% and 4.2% after solution treatment at $495^{\circ}C$ for 5hours, and were approximately 0%, 0.36% and 2% after solution treatment at $515^{\circ}C$ for 5hours. The best combination of tensile properties was obtained when the as-cast alloy was solution treated at $515^{\circ}C$ for 3hours followed by aging at $180^{\circ}C$ for 10 hours. Detailed DTA and TEM study showed that the strengthening behavior during aging was due to enhanced precipitation of the platelet type fine ${\theta}'$ phase.

• 한국환경농학회지
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• 제15권4호
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• pp.506-519
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• 1996

The water quality in the rural areas is degrading due to a variety of causes such as the increase of the urban sewage and industrial wastes, the disposal of solid wastes, the growth of livestock waste, the growth of leisure facilities, the establishment of agricultural industry estates and etc. The water pollutants are scarce while the effluent is increasing from wide scattered sources. The technology specifically designed for the rural wastes water treatment plant needs to be implemented with improvement of agricultural water quality. 1. An integrated management measures against water pollution sources. The prevention of water pollution is the best measures in the environmental pollution. Hence, the most effective measures needs to be against the sources. Small-scale water treatment plants needs to be constructed in each village in the rural areas. As for the industrial effluent, the effluent discharge needs to be strictly monitored. Government subsidy for the establishment of treatment plant for livestock wastes is necessary. 2. The establishment of national-wide network for agricultural water quality. The network for agricultural water quality have been operated to conserve the agricultural water quality, and to develop management policies by the assessment of water pollution in the rural areas. The results of agricultural water quality network indicates that the water quality is degrading not only around urban areas but also in the distant rural areas, and the water quality at the pumping stations and weirs is worse than that of reservoirs. 3. The legal, systematic, and technical approaches for the agricultural water quality management. The actions currently implemented for the improvement of agricultural water quality involve temporary measures such as the improvement of irrigation facilities. These contingency measures are not effective in the long-term, and sometimes bring secondary pollution. Therefore, integrated measures covering the whole water environment such as the flow, quality, river morphology, aquatic ecosystem, and the surrounding environment, need be invented and implemented. Besides, the legal, systematic, and technical frameworks for the management are not fully established so far. The technology for the treatment of rural water pollution should be refined afterwards, and the research for the development of rural waste water treatment plant should be carried out.

• 상하수도학회지
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• 제29권4호
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• pp.493-502
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• 2015

In accordance with the Watershed Sewer System Maintenance Plan enforced on February 2, 2013, the different compliance concentration of effluent limit be applied to effluent discharged from public sewage treatment works(PSTWs) in each watershed on the basis of water quality thereof. With the introduction of watershed sewer system, it is necessary to set the compliance concentration of effluent limit for PSTWs situated in the watershed, by region and PSTW size, to achieve water quality criteria for regional watersheds or target water quality under TMDL program. Watershed Environmental Agencies establish the Watershed Sewer System Maintenance Plan and set the compliance concentrations of effluent limit for PSTWs under the plan. The agencies plan to apply tougher effluent BOD concentration limits in Class I to IV areas. Effluent BOD concentration limits will be toughened from 5~10 mg/L to 3 mg/L in class II~III areas, from 10mg/L to 5mg/L in class IV areas. Uniform application of effluent BOD concentration limits to PSTWs in the watershed sewer system need to be complemented considering type of sewage treatment technology employed and watershed characteristics. Therefore, this study presents method to determine the compliance concentration of effluent limit from PSTWs in the watershed.

• Journal of the Korean Wood Science and Technology
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• 제28권3호
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• pp.9-13
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• 2000

본 연구는 해마다 100만 톤 이상이 생산되는 국내산 왕겨를 이용하여 왕겨보드를 제조함에 있어, 무처리 왕겨로 제조한 왕겨보드의 기계적 성질의 단점을 보완하기 위하여 왕겨를 전처리함으로써 그 물리 기계적 성질을 개선하기 위해 실시되었다. 연구결과를 요약하면, 무처리, 증자처리 및 가성소다로 알칼리처리한 왕겨보드보다 폭쇄처리한 왕겨보드가 휨강도 및 박리강도가 더 높았으며, 이때 적정 폭쇄처리 조건은 압력 20kgf/$cm^2$, 시간 1분과 압력 25kgf/$cm^2$, 1분이었다. 무처리 왕겨보드의 경우 휨강도, 박리강도 모두 KS를 만족시키지 못한 반면, 폭쇄처리 왕겨 보드의 경우 KS PB 18.0형의 기준을 모두 만족시켰으며, PB 대조구와 비교할 때 동등한 강도를 보였다. 기타 왕겨 전처리의 경우에 있어서도 가성소다처리보다는 증자처리가 왕겨보드의 강도를 향상시키는 것으로 나타났다.

• Journal of Preventive Medicine and Public Health
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• 제56권1호
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• pp.41-49
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• 2023

Objectives: Rwanda reported a stunting rate of 33% in 2020, decreasing from 38% in 2015; however, stunting remains an issue. Globally, child deaths from malnutrition stand at 45%. The best options for the early detection and treatment of stunting should be made a community policy priority, and health services remain an issue. Hence, this research aimed to develop a model for predicting stunting in Rwandan children. Methods: The Rwanda Demographic and Health Survey 2019-2020 was used as secondary data. Stratified 10-fold cross-validation was used, and different machine learning classifiers were trained to predict stunting status. The prediction models were compared using different metrics, and the best model was chosen. Results: The best model was developed with the gradient boosting classifier algorithm, with a training accuracy of 80.49% based on the performance indicators of several models. Based on a confusion matrix, the test accuracy, sensitivity, specificity, and F1 were calculated, yielding the model's ability to classify stunting cases correctly at 79.33%, identify stunted children accurately at 72.51%, and categorize non-stunted children correctly at 94.49%, with an area under the curve of 0.89. The model found that the mother's height, television, the child's age, province, mother's education, birth weight, and childbirth size were the most important predictors of stunting status. Conclusions: Therefore, machine-learning techniques may be used in Rwanda to construct an accurate model that can detect the early stages of stunting and offer the best predictive attributes to help prevent and control stunting in under five Rwandan children.

• Membrane and Water Treatment
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• 제10권6호
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• pp.471-484
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• 2019

The complex combination of organic contaminants in the wastewater made water treatment challenging; hence, organic matter in water bodies is usually measured in terms of organic carbon. Since it is important to identify the types of compounds when deciding suitable treatment methods, this study implemented a quantitative and qualitative analysis of the organic matter content in an actual graywater sample from Ulsan, Republic of Korea using mass spectroscopy (MS). The graywater was treated using adsorption to remove the organic contaminants. Using orbitrap MS, the organic matter content between an untreated graywater and the treated effluent were compared which yielded a significant formula count difference for the samples. It was revealed that CHON formula has the highest removal count. Isotherm studies found that the Freundlich equation was the best fit with a coefficient of determination ($R^2$) of 0.9705 indicating a heterogenous GAC surface with a multilayer characteristic. Kinetics experiments fit the pseudo-second order equation with an $R^2$ of 0.9998 implying that chemisorption is the rate-determining step between the organic compounds and GAC at rate constant of $52.53g/mg{\cdot}h$. At low temperatures, the reaction between GAC and organic compounds were found to be spontaneous and exothermic. The conditions for optimization were set to achieve a maximum DOC and TN removal which yielded removal percentages of 94.59% and 80.75% for the DOC and TN, respectively. The optimum parameter values are the following: pH 6.3, 2.46 g of GAC for every 30 mL of graywater sample, 23.39 hrs contact time and $38.6^{\circ}C$.

• International Journal of Computer Science & Network Security
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• 제23권1호
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• pp.53-63
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• 2023

Many researchers are trying hard to minimize the incidence of cancers, mainly Gastric Cancer (GC). For GC, the five-year survival rate is generally 5-25%, but for Early Gastric Cancer (EGC), it is almost 90%. Predicting the onset of stomach cancer based on risk factors will allow for an early diagnosis and more effective treatment. Although there are several models for predicting stomach cancer, most of these models are based on unbalanced datasets, which favours the majority class. However, it is imperative to correctly identify cancer patients who are in the minority class. This research aims to apply three class-balancing approaches to the NHS dataset before developing supervised learning strategies: Oversampling (Synthetic Minority Oversampling Technique or SMOTE), Undersampling (SpreadSubsample), and Hybrid System (SMOTE + SpreadSubsample). This study uses Naive Bayes, Bayesian Network, Random Forest, and Decision Tree (C4.5) methods. We measured these classifiers' efficacy using their Receiver Operating Characteristics (ROC) curves, sensitivity, and specificity. The validation data was used to test several ways of balancing the classifiers. The final prediction model was built on the one that did the best overall.

• Preventive Nutrition and Food Science
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• 제21권1호
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• pp.44-51
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• 2016

The objective of this study was to determine the factors responsible for the changed physiochemical properties of unpeeled shrimp treated in cold phosphate solution ($2{\sim}4^{\circ}C$) with the intervention of 4 factors: phosphate concentration, dipping time, rotation speed, and volume of brine solution. Response surface analysis was used to characterize the effect of the phosphate treatment on shrimps by running 33 treatments for optimizing the experiment. For each treatment, phosphate amount, moisture content, and weight gain were measured. The results showed that phosphate concentration is the most important factor than other factors for facilitating phosphate penetration in the meat of the shrimp and for getting the best result. The optimum condition of phosphate-treated shrimp in this study was 110 to 120 min dipping time, 500 to 550 mL brine solution for 100 g shrimp sample, and 190 to 210 rpm agitation speed. The studied conditions can be applied in fisheries and other food industries for good phosphate treatments.