• The Journal of Korean Institute of Next Generation Computing
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• v.13 no.3
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• pp.72-83
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• 2017

GPUs can provide high throughput with latency hiding by executing many warps in parallel. MSHR(Miss Status Holding Registers) for L1 data cache tracks cache miss requests until required data is serviced from lower level memory. In recent GPUs, excessive requests for cache resources cause underutilization problem of GPU resources due to cache resource reservation fails. In this paper, we propose a new warp scheduling technique to reduce stall cycles under MSHR resource shortage. Cache miss rates for each warp is predicted based on the observation that each warp shows similar cache miss rates for long period. The warps showing low miss rates or computation-intensive warps are given high priority to be issued when MSHR is full status. Our proposal improves GPU performance by utilizing cache resource more efficiently based on cache miss rate prediction and monitoring the MSHR entries. According to our experimental results, reservation fail cycles can be reduced by 25.7% and IPC is increased by 6.2% with the proposed scheduling technique compared to loose round robin scheduler.

• Health Policy and Management
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• v.33 no.2
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• pp.141-156
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• 2023

Background: As the population rapidly ages, older adults are increasingly likely to experience mobility problems. This study aims to explore the characteristics related to an elderly person's willingness to live in a nursing home if they have mobility problems Methods: This study analyzed data from 9,917 older adults (5,976 young-old and 3,941 old-old) obtained from the 2020 National Survey of Older Koreans. The dependent variable was the intended place of residence for older adults with mobility problems. Independent variables included various characteristics: (1) sociodemographic and social support, (2) health and functional status, and (3) residential environment. Rao-Scott chi-square tests and survey logistic regression analyses were performed for the young-old and old-old, respectively. Results: The intention to live in a nursing home was significantly different between the young-old (30.4%) and the old-old (34.7%) (p=0.009). According to fully adjusted multivariable analyses, for the young-old, the odds ratio of intending to live in a nursing home was significantly higher in social security benefit recipients (1.45; 95% confidence interval [CI], 1.06-1.97) compared to other individuals. The odds ratio was higher in unmarried (divorced, separated, widowed, or never-married) individuals for both young-old (1.41; 95% CI, 1.22-1.63) and old-old (1.34; 95% CI, 1.09-1.65) age groups, compared to their respective married counterparts. Conclusion: The results of this study suggest that in an aging society, health and social policies should be designed considering the different characteristics of the elderly to improve their health, function, and quality of life.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.7-15
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• 2023

The electric submersible pump (ESP) has been operating in production wells around the world because of its high applicability and operational efficiency among artificial lift techniques. When operating an ESP in a reservoir, variables such as temperature, pressure, gas/oil ratio, and flow rate are factors that affect ESP performance. In particular, free gas in the production fluid is a major factor that reduces the life and operational efficiency of ESP. This study presents the flow loop system which can implement the performance and damage tests of ESP considering field operating conditions to quantitatively analyze the variables that affect ESP performance. The developed apparatus in an integrated system that can diagnose the failure and causes of ESP, and detect leak of tubing by linking ESP and tubing as one system. In this study, the flow conditions for stable operation of ESP were identified through single phase and two phase flow experiments related to evaluation for the performance of ESP. The results provide the basic data to develop the failure prediction and diagnosis program of ESP, and are expected to be used for real-time monitoring for optimal operating conditions and failure diagnosis for ESP operation.

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.71-78
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• 2023

In general, electric submersible pumps (ESPs), which have an average life of 1.0 to 1.5 years, experience a decrease in performance and a reduction in life of the pump depending on oil and gas reservoir characteristics and operating conditions in wells. As the result, the failure of ESP causes high well workover costs due to retrieval and installation, and additional costs due to shut down. In this study, a flow loop system was designed and established to predict the life of ESP in long­term operation of oil and gas wells, and the life cycle data of ESP from the time of installation to the time of failure was acquired and analyzed. Among the data acquired from the system, flow rate, inlet and outlet temperature and pressure, and the data of the vibrator installed on the outside of ESP were analyzed, and then the performance status according to long-term operation was classified into five stages: normal, advice I, advice II, maintenance, and failed. Through the experiments, it was found that there was a difference in the data trend by stage during the long­term operation of the ESP, and then the condition of the ESP was diagnosed and the failure of the pump was predicted according to the operating time. The results derived from this study can be used to develop a failure prediction program and data analysis algorithm for monitoring the condition of ESPs operated in oil and gas wells.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.2
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• pp.125-134
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• 2023

The Naedeokri and Nonggeori granites are early Proterozoic granites of the Taebaek-Sangdong area in the northeastern part of the Yeongnam Massif. In this paper, rare earth elements (REEs) concentrations of the minerals in Naedeokri and Nonggeori granites and Rb-Sr mineral isochron age are reported. Except zircon, the constituent minerals such as mica, feldspar, quartz, and tourmaline show LREE-enriched and HREE-depleted REE patterns with relatively large Eu negative anomaly. However, zircon has geochemical characteristic of LREE- and HREE-enriched REE pattern with large Eu positive anomaly. This pattern suggests that zircon should be hydrothermal zircon due to deuteric hydrothermal alteration. In addition, the Rb-Sr mineral age of Naedeokri granite indicates an age value of 1.814±142(2σ) Ma. The Rb-Sr whole rock age including pervious data of Naedeokri and Nogggeori granite indicates an age value of 1,707±74(2σ) Ma. This value is younger than the Sm-Nd isochron of 1.87 Ga, indicating that the Rb-Sr isotope system may be re-homogenized by hydrothermal alteration during the transition from a magmatic to a hydrothermal system.

• Journal of Industrial Convergence
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• v.21 no.7
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• pp.19-27
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• 2023

As the secondary battery market expands, the process of producing laterite ore using the rotary kiln and electric furnace method is expanding worldwide. As ESG management expands, the management of air pollutants such as nitrogen oxides in exhaust gases is strengthened. The rotary kiln, one of the main facilities of the pyrometallurgy process, is a facility for drying and preliminary reduction of ore, and it generate nitrogen oxides, thus prediction of nitrogen oxide is important. In this study, LSTM for regression prediction and LightGBM for classification prediction were used to predict and then model optimization was performed using AutoML. When applying LSTM, the predicted value after 5 minutes was 0.86, MAE 5.13ppm, and after 40 minutes, the predicted value was 0.38 and MAE 10.84ppm. As a result of applying LightGBM for classification prediction, the test accuracy rose from 0.75 after 5 minutes to 0.61 after 40 minutes, to a level that can be used for actual operation, and as a result of model optimization through AutoML, the accuracy of the prediction after 5 minutes improved from 0.75 to 0.80 and from 0.61 to 0.70. Through this study, nitrogen oxide prediction values can be applied to actual operations to contribute to compliance with air pollutant emission regulations and ESG management.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.362-367
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• 2023

Recently, research and development of proton exchange membrane fuel cells (PEMFC) membranes are progressing in the direction of thinning to reduce prices and improve performance. Demand for hydrogen-powered vehicles for commercial vehicles is also increasing, and their durability should be five times greater than those for passenger vehicles. Despite the thinning of the membranes, the durability of the membranes must be increased five times, so the improvement of the durability of the membranes has become more important. Since the acceleration durability evaluation time also needs to be shortened, the protocol using oxygen instead of air in the existing protocol was applied to a 10 ㎛ thin membrane to evaluate durability. The accelerated durability test (Open circuit voltage holding) was terminated at 720 hours. If the air-based department of energy (DOE) protocol was used, a lifespan of 450,000 km of driving hours would be expected, with a durability of about 1,500 hours. During the chemical durability evaluation, the active area of the electrode decreased by 51%, suggesting that catalyst degradation had an effect on membrane durability. Reducing the catalyst degradation rate is expected to increase membrane durability.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.356-361
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• 2023

In order to improve the durability of the proton exchange membrane fuel cell (PEMFC), it is important to accurately evaluate the durability of the polymer membrane in a short time. The test conditions for chemically accelerated durability evaluation of membranes are high voltage, high temperature, low humidity, and high gas pressure. It can be said that the protocol is developed by changing these conditions. However, the relative influence of each test condition on the degradation of the membrane has not been studied. In chemical accelerated degradation experiment of the membrane, the influence of 4 factors (conditions) was examined through the factor experiment method. The degree of degradation of the membrane after accelerated degradation was determined by measuring the hydrogen permeability and effluent fluoride ion concentration, and it was possible to determine the degradation order of the polymer membrane under 8 conditions by the difference in fluoride ion concentration. It was shown that the influence of the membrane degradation factor was in the order of voltage > temperature > oxygen pressure > humidity. It was confirmed that the degradation of the electrode catalyst had an effect on the chemical degradation of the membrane.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.3
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• pp.471-485
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• 2023

Recently, due to the nature of blockchain that guarantees users' anonymity, more and more cases are being exploited for crimes such as illegal transactions. However, cryptocurrency is protected in cryptocurrency wallets, making it difficult to recover criminal funds. Therefore, this study acquires artifacts from the data and memory area of a local PC based on user behavior from four browser extension wallets (Metamask, Binance, Phantom, and Kaikas) to track and retrieve cryptocurrencies used in crime, and analyzes how to use them from a digital forensics perspective. As a result of the analysis, the type of wallet and cryptocurrency used by the suspect was confirmed through the API name obtained from the browser's cache data, and the URL and wallet address used for the remittance transaction were obtained. We also identified Client IDs that could identify devices used in cookie data, and confirmed that mnemonic code could be obtained from memory. Additionally, we propose an algorithm to measure the persistence of obtainable mnemonic code and automate acquisition.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.3
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• pp.363-374
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• 2023

A white-box environment refers to a situation where the internal information of an algorithm is disclosed. The AES white-box encryption was first announced in 2002, and in 2016, a side-channel analysis for white-box encryption called Differential Computation Analysis (DCA) was proposed. DCA analysis is a powerful side-channel attack technique that uses the memory information of white-box encryption as side-channel information to find the key. Although various countermeasure studies against DCA have been published domestically and internationally, there were no evaluated or analyzed results from experiments applying the hiding technique using dummy operations to DCA analysis. Therefore, in this paper, we insert LU T-shaped dummy operations into the WBC-AES algorithm proposed by S. Chow in 2002 and quantitatively evaluate the degree of change in DCA analysis response depending on the size of the dummy. Compared to the DCA analysis proposed in 2016, which recovers a total of 16 bytes of the key, the countermeasure proposed in this paper was unable to recover up to 11 bytes of the key as the size of the dummy decreased, resulting in a maximum decrease in attack performance of about 68.8%, which is about 31.2% lower than the existing attack performance. The countermeasure proposed in this paper confirms that the attack performance significantly decreases as smaller dummy sizes are inserted and can be applied in various fields.