• 한국재료학회지
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• 제21권1호
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• pp.1-7
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• 2011

Methods of producing hydrogen include steam reforming, electrochemical decomposition of water, and the SI process. Among these methods, the Sulfur iodine process is one of the most promising processes for hydrogen production. The thermochemical sulfur-iodine (SI) process uses heat from a high-temperature-gas nuclear reactor to produce $H_2$ gas; this process is known for its production of clean energy as it does not emit $CO_2$ from water. But the SI-process takes place in an extremely corrosive environment for the materials. To endure SI environments, the materials for the SI environment will have to have strong corrosion resistance. This work studies the corrosion resistances of the Fe-Si, Ni-Ti and Ni Alloys, which are tested in SI-process environments. Among the SI-process environments, the conditions of boiling sulfuric acid and decomposed sulfuric acid are selected in this study. Before testing in boiling sulfuric acid environments, the specimens of Fe-4.5Si, Fe-6Si, Ni-4.5Si, Ni-Ti-Si-Nb and Ni-Ti-Si-Nb-B are previously given heat treatment at $1000^{\circ}C$ for 48 hrs. The reason for this heat treatment is that those specimens have a passive film on the surface. The specimens are immersed for 3~14 days in 98wt% boiling sulfuric acid. Corrosion rates are measured by using the weight change after immersion. The corrosion rates of the Fe-6Si and Ni-Ti-Si-Nb-B are found to decrease as the time passes. The corrosion rates of Fe-6si and Ni-Ti-Si-Nb-B are measured at 0.056 mm/yr and 0.16 mm/yr, respectively. Hastelloy-X, Alloy 617, Alloy 800H and Haynes 230 are tested in the decomposed sulfuric acid for one day. Alloy 800H was found to show the best corrosion resistance among the materials. The corrosion rate of Alloy 800H is measured at -0.35 mm/yr. In these results, the corrosion resistance of materials depends on the stability of the oxide film formed on the surface. After testing in boiling sulfuric acid and in decomposed sulfuric acid environments, the surfaces and compositions of specimens are analyzed by SEM and EDX.

• Smart Structures and Systems
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• 제26권2호
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• pp.241-251
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• 2020

Due to the undeniable importance of approximating the concrete compressive strength (CSC) in civil engineering, this paper focuses on presenting four novel optimizations of multi-layer perceptron (MLP) neural network, namely artificial bee colony (ABC-MLP), grasshopper optimization algorithm (GOA-MLP), shuffled frog leaping algorithm (SFLA-MLP), and salp swarm algorithm (SSA-MLP) for predicting this crucial parameter. The used dataset consists of 103 rows of information concerning seven influential parameters (cement, slag, water, fly ash, superplasticizer, fine aggregate, and coarse aggregate). In this work, the best-fitted complexity of each ensemble is determined by a population-based sensitivity analysis. The GOA distinguished its self by the least complexity (population size = 50) and emerged as the second time-effective optimizer. Referring to the prediction results, all tested algorithms are able to construct reliable networks. However, the SSA (Correlation = 0.9652 and Error = 1.3939) and GOA (Correlation = 0.9629 and Error = 1.3922) performed more accurately than ABC (Correlation = 0.7060 and Error = 4.0161) and SFLA (Correlation = 0.8890 and Error = 2.5480). Therefore, the SSA-MLP and GOA-MLP can be promising alternatives to laboratorial and traditional CSC evaluative methods.

• Smart Structures and Systems
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• 제33권1호
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• pp.65-91
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• 2024

The use of five optimization techniques for the prediction of a strength-based concrete mixture's best-fit model is examined in this work. Five optimization techniques are utilized for this purpose: Slime Mold Algorithm (SMA), Black Hole Algorithm (BHA), Multi-Verse Optimizer (MVO), Vortex Search (VS), and Whale Optimization Algorithm (WOA). MATLAB employs a hybrid learning strategy to train an artificial neural network that combines least square estimation with backpropagation. Thus, 72 samples are utilized as training datasets and 31 as testing datasets, totaling 103. The multi-layer perceptron (MLP) is used to analyze all data, and results are verified by comparison. For training datasets in the best-fit models of SMA-MLP, BHA-MLP, MVO-MLP, VS-MLP, and WOA-MLP, the statistical indices of coefficient of determination (R²) in training phase are 0.9603, 0.9679, 0.9827, 0.9841 and 0.9770, and in testing phase are 0.9567, 0.9552, 0.9594, 0.9888 and 0.9695 respectively. In addition, the best-fit structures for training for SMA, BHA, MVO, VS, and WOA (all combined with multilayer perceptron, MLP) are achieved when the term population size was modified to 450, 500, 250, 150, and 500, respectively. Among all the suggested options, VS could offer a stronger prediction network for training MLP.

• 스마트미디어저널
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• 제10권2호
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• pp.76-83
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• 2021

스마트폰과 태블릿과 같은 스마트 기기의 발달과 사용이 증가함에 따라, 모바일 기기를 기반으로 한 모바일 어플리케이션 시장이 급속도로 커지고 있다. 모바일 어플리케이션 사용자는 어플리케이션을 사용 경험을 공유하고자 리뷰를 남기는데, 이를 분석하면 소비자들의 다양한 니즈를 파악할 수 있고 어플리케이션 개발자들은 소비자들이 작성한 리뷰를 통해 애플리케이션의 개선을 위한 유용한 피드백을 받을 수 있다. 그러나 소비자들의 남기는 많은 양의 리뷰를 수작업으로 분석하기 위해서는 많은 시간과 비용을 지불해야하기 때문에 이를 최소화 할 방안을 마련할 필요성이 존재한다. 이에 본 연구에서는 구글 플레이스토어(Google PlayStore)의 배달 어플리케이션 사용자 리뷰를 수집한 후 머신러닝과 딥러닝 기법을 활용하여 어플리케이션 기능 장점, 단점, 기능 개선 요청, 버그 보고의 4가지 범주로 분류하는 방법을 제안한다. 연구 결과, Hugging Face의 pretrain된 BERT기반 Transformer모델의 성능의 경우 위의 4개의 범주에 대한 f1 score값은 차례대로 0.93, 0.51, 0.76, 0.83으로 LSTM, GRU보다 뛰어난 성능을 보인 것을 확인할 수 있었다.

• The Journal of Asian Finance, Economics and Business
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• 제8권2호
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• pp.625-633
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• 2021

This study analyzes the impact of the reward variable on employees' performance through work motivation and employee engagement. This study's specific purpose is to investigate employee engagement's mediating role in the relationship between reward and employee performance. The sample of research is the employee at Sukorejo, Pasuruan Indonesia. The sample is permanent employees at manufacture corporate. The sample size is 150 employees of the total 759 workers through the calculation of the Slovin formula. Respondents in this study were employees with the criteria for having worked for at least last five years. The data obtained is in the form of answers from employees to the statements submitted. The data analysis was used structural equation modeling partial least square. To test the relationship between variables, it was equipped with a Sobel mediation test of statistics. SmartPLS 3.0 is used to help analyze the relationship between variables. The result shows that the reward does not have a direct influence on the performance of employees. However, it has a significant positive effect on the performance of employees through employee engagement. While working motivation variable does not have the role as a mediation variable related to the effect of reward on employee performance.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.285-296
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• 2014

Recently, the use of Smartphones has been widespread and changed our lives positively. Smartphones which are called as PC in the hand and spread general people rapidly are becoming a medium to use generally various functions such as internet, work, multimedia, etc. beyond the simple function of telephone communication in the past. However, the excessive use of Smartphones has also produced many side effects. The purpose of this study is to examine the Smartphone Addiction on Daily Life Impact. This model tests various theoretical research hypotheses relating to Self-Esteem, Enjoyment, Flow, Social Impact, Smartphone Addiction and Daily life impact. The proposed model is analyzed to target 299 University Students and Smart Partial Least Square(PLS) 2.0 have been utilized for deriving the study results. The Result of Hypothesis testing are as follows. First, Self-Esteem negatively influence Smartphone Addiction. Second, Enjoyment, Flow and Social Impact positively influence Smartphone Addiction. Third, Smartphone Addiction positively influence Daily Life impact. This Research makes a basic research for smart phone addiction papers that will be investigated a lot in the future.

• 한국해양바이오학회지
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• 제13권2호
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• pp.76-85
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• 2021

Crassostrea gigas were fermented using L. brevis BJ20 to prepare fermented oyster extract (FO). The participants of this study were randomly assigned to FO and placebo (CON) groups. The FO group was given 1.0 g of FO supplementation and the CON group was given sucrose each day for eight weeks. The effects of FO supplementation on body composition, muscula r strength, and blood factors associated with muscle growth were assessed. The FO supplement was enriched with arginine (6,183.3 mg), phenylalanine (217.9 mg), leucine (122.6 mg), isoleucine (59.8 mg), valine (16.4 mg), and γ-amino butyric acid (GABA, 1,053.7 mg). The total fat was significantly decreased in the FO group compared with the CON group (p < 0.05). 60D/S Ext.T/Wo rk and 60D/S Flex.T/Work concomitantly with 60D/S Flex.PeakTQ/BW were significantly increase d by FO treatment compared to CON group (p < 0.05). However, posture stability was not significa ntly different between the groups. The levels of angiotensin-converting enzyme were significantly decreased within the FO group (p < 0.05). The FO group showed significantly decreased levels of tumor necrosis factor-α and increased levels of human growth hormone compared with the CON group (p < 0.01). The levels of insulin-like growth factor-1 increased (p < 0.01) in the FO group while that of creatine kinase and triglyceride decreased significantly compared with the CON group (p < 0.05). These results demonstrated that FO supplementation is effective in preventing sarcopenic obesity and maintaining and strengthening muscular function in elderly wom en. Hence, FO supplements can be used as functional ingredients for these benefits.

• 한국환경복원기술학회지
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• 제24권6호
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• pp.35-48
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• 2021

In Suwon, the overall hygiene of the city is threatened by the emergence of the rook(Corvus fugilegus) in the city. Rooks began to appear in November of 2016 and has continued to appear from November to March every year. In order to eradicate or to prepare an alternative habitat for rooks, this study aimed to identify the preferred habitat and specific environmental variables. Therefore, in this work, we aim to understand the predicted distribution of rooks in Suwon City with citizen science and through MaxENT, the most widely utilized habitat modeling using citizen science to analyze the preferred habitat of harmful tides appearing in urban areas. In this study, seven environmental variables were chosen: biotope group complex, building floor, vegetation, euclidean distance from farmland, euclidean distance from streetlamp, and euclidean distance from pole and DEM. Among the estimated models, after the time period of sunrise (08:00~18:00) the contribution percentage were as following: euclidean distance from arable land(39.2%), DEM(25.5%), euclidean distance from streetlamp(22.3%), euclidean distance from pole(7.1%), biotope group complex(4.9%), building floor(1%), vegetation(0%). In the time period after sunset(18:00~08:00) the contribution percentage were as following: biotope group complex(437.4%), euclidean distance from pole(26.8%), DEM(13.4%), euclidean distance from streetlamp(11.8%), euclidean distance from farmland(7.9%), building floor(1.4%), vegetation(1.3%).

• 식물병연구
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• 제30권2호
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• pp.194-198
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• 2024

화상병은 전정 도구 등에서 장시간 생존이 가능하고 작업 도구를 통해 화상병균이 전파될 수 있다. 특히, 우리나라에서는 꽃이나 어린 과실, 도장지 등을 제거하기 위해 전정 작업이 수시로 이루어지는데 이런 농작업이 화상병 확산의 주요인으로 알려져 있다. 따라서, 본 연구에서는 전정 가위에 묻어 있는 화상병균을 완전히 멸균하기 위하여 국내에 유통되는 소독제의 소독 효과를 검증하고 이를 이용하여 효과적인 소독 방법을 구명하였다. 화상병균을 가위 날에 접종 후에 침지 소독할 경우 70% 에탄올 및 1%와 0.2% 차아염소산나트륨의 경우에는 침지 후 10초가 지나면 바로 멸균되는 반면, 30% 이산화염소는 소독 효과가 거의 보이지 않았다. 분무 처리로 소독할 경우에는 70% 에탄올은 분무 1초 후에는 바로 멸균이 되었지만 1%와 0.2% 차아염소산나트륨은 각각 10초와 60초 후에 멸균되었다. 자연적으로 화상병이 발병한 가지를 5회 및 100회 절단한 후 전정 가위 날 표면에 묻어 있는 화상병균에 대한 침지 소독 시간에 따른 제거 효과를 검증한 결과, 70% 에탄올에 30초 동안 침지 처리한 경우 완전히 세균이 멸균되지 않았지만 60초 이상에서는 세균이 멸균되었다. 이런 결과를 볼 때 현장에서 전정 작업 시 전정 가위를 70% 에탄올에 60초 이상 수시로 침지하여 소독할 것을 제안한다.

• 자원환경지질
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• 제56권2호
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• pp.185-199
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• 2023

This study aimed to predict the effects of water ecology on the supply of hydrothermal energy to model a housing complex in Eco Delta Smart Village in Busan. Based on the results, engineering measures were recommended to minimize problems due to possible temperature variations on the supply of hydrothermal energy from the river. The current distribution of fish, benthic macroinvertebrates, and phytoplankton in the Pyeonggang Stream was monitored to determine their effects on water ecology. In the research area, five species and three families of fish were observed. The dominant species was Lepomis macrochirus, and the subdominant species was Carassius auratus. Twenty-five species and 21 families of benthic macroinvertebrates were found. The distribution of aquatic insects was poor in this area. The dominant species were Chironomidae sp., Lymnaea auricularia, Appasus japonicus, and Caridina denticulata denticulata in February, May, July, and October. Dominant phytoplankton were Aulacoseira ambigua and Nitzschia palea in February and May. Microcystis sp. was dominant in July and October. The health of the ecology the Pyeonggang Stream was assessed as D (bad) according to the benthic macroinvertebrate index (BMI). Shifts in the location of the discharge point 150 m downstream from intake points and discharge through embedded rock layer after adding equal amounts of stream water as was taken at the beginning were suggested to minimize water temperature variations due to the application of hydrothermal energy. When the scenario (i.e., quantity of water intake and dilution water, 1,600 m³/d and water temp. difference ±5 ℃) was realized, variations in water temperature were assessed at -0.19 ℃ and 0.59 ℃ during cooling and heating, respectively, at a point 10 m downstream. Water temperatures recorded at -0.20 ℃ and 0.68 ℃ during cooling and heating, respectively, at a point 10 m upstream. All stream water temperatures after the application of hydrothermal energy recovered within 24 hours. Future work on the long-term monitoring of ecosystems is suggested, particularly to analyze the influence of the water environment on hydrothermal energy supply operations.