• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.197-208
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• 2022

The existence of shallow bedrock and the desire to use underground space necessitate the use of blasting methods. The standard blasting method under water after drilling is associated with certain technical difficulties, including reduced detonation power, the use of a fixed charge per delay, and decoupling. However, there is no blasting method to replace the existing blasting method. In this paper, a dry hole charged with ANFO blasting is assessed while employing a dry hole pumping system to remove water from the drill borehole. Additional standard blasting is also utilized to compare the blasting performances of the two methods. The least-squares linear regression method is adopted to analyze the blasting vibration velocity quantitatively using the measured vibration velocity for each blasting method and the vibration velocity model as a function of the scaled distance. The results show that the dry hole charged with ANFO blasting will lead to greater damping of the blasting vibration, more energy dissipation to crush the surrounding rock, and closer distances for the allowable velocity of the blasting vibration. Also, standard blasting shows much longer influencing distances and a wider range of the blasting pattern. The pilot test confirms the blasting efficiency of dry hole charged with ANFO blasting.

• The Journal of the Convergence on Culture Technology
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• v.9 no.4
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• pp.363-374
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• 2023

This study is a descriptive research study to confirm the care efficacy and empathy competency of nursing hospital nurses and analyze the factors to improve person-centered care behavior, provide theoretical and practical information accordingly, and prepare basic data. The study collected data from March 20, 2023 to April 20, 2023, targeting 146 nurses at a nursing hospital for the elderly in C region located in G province, and finally analyzed a total of 144 copies. Using IBM SPSS/25, descriptive statistics t-test, ANOVA, and correlation multiple regression analysis were analyzed. As a result of analyzing the variables that affect the subject's person-centered care by hierarchical multiple regression, the higher the caring efficacy and empathy capacity, the more the person-centered care was affected, and the explanatory power was 31.5%. As a result of this study, empathy competency and care efficacy were found to have an effect on person-centered care. It is thought that various measures should be prepared to improve the care efficacy and empathy competency for the efficient nursing performance of person-centered care of nursing hospital nurses.

• Information Systems Review
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• v.26 no.2
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• pp.137-153
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• 2024

This study aimed to propose early diagnosis and management of dementia, which is increasing in aging societies, and suggest commercial utilization strategies by leveraging digital healthcare technologies, particularly lifelog data collected from wearable devices. By introducing new approaches to dementia prevention and management, this study sought to contribute to the field of dementia prediction and prevention. The research utilized 12,184 pieces of lifelog information (sleep and activity data) and dementia diagnosis data collected from 174 individuals aged between 60 and 80, based on medical pathological diagnoses. During the research process, a multidimensional dataset including sleep and activity data was standardized, and various machine learning algorithms were analyzed, with the random forest model showing the highest ROC-AUC score, indicating superior performance. Furthermore, an ablation test was conducted to evaluate the impact of excluding variables related to sleep and activity on the model's predictive power, confirming that regular sleep and activity have a significant influence on dementia prevention. Lastly, by exploring the potential for commercial utilization strategies of the developed model, the study proposed new directions for the commercial spread of dementia prevention systems.

• Journal of Microbiology and Biotechnology
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• v.10 no.3
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• pp.349-354
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• 2000

Abstract A facultative alkalophilic gram-negative Vibrio metschnikovii strain RH530, isolated from the wastewater, produced several alkaline proteases (VAP) including six alkaline serine proteases and a metalloprotease. From this strain, high yielding YAP mutants were isolated by NTG treatment. The isolated mutant KS1 showed nine times more activity than the wild-type after optimization of the culture media. The production was regulated by catabolite repression when glucose was added to the medium. The effects of several organic nitrogen sources on the production of the YAP were investigated to avoid catabolite repression. The combination of 4% wheat gluten meal (WGM), 1.5% cotton seed flour (eSF), and 5% soybean meal (SBM) resulted in the best production when supplemented with 1% NaCl. The YAP showed a resistance to surfactants such as $sodium-{\alpha}-olefin$ sulfonate (AOS), polyoxy ethylene oxide (POE), and sodium dodecyl sulfate (SDS), yet not to linear alkylbenzene sulfonate (LAS). However, the activity of the YAP was restored completely when incubated with LAS in the presence of POE or $Na_2SO_4$. The YAP was stable in a liquid laundry detergent containing 6.6% SLES (sodium lauryl ether sulfate), 6.6% LAS, 19.8% POE, and stabilizing agents for more than two weeks at $40^{\circ}C$, but the stability was sharply decreased even after 1 day when incubated at $60^{\circ}C$. A washing performance test with the YAP exhibited it to be a good washing power by showing 51 % and 60% activity at $25^{\circ}C{\;}and{\;}40^{\circ}C$, respectively, thereby indicating that the YAP also has a good detergency at a low temperature. All the results suggest that the YAP produced from the mutant strain KSI has suitable properties for use in laundry detergents.rgents.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.3
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• pp.205-212
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• 2013

The objective of this study was to investigate the feasibility of replacing a conventional plate fin-tube evaporator with a spiral fin-tube evaporator by comparing the performance of domestic refrigerator-freezers adopting either the plate fin-tube evaporator or spiral fin-tube evaporator. Experiments were conducted for the domestic refrigerator-freezers using either a 2-column and 15-row plate fin-tube evaporator or three spiral fin-tube evaporators with 11, 13, and 15 tube rows (N). The optimum refrigerant charge decreased with a decrease in the number of tube rows. The power consumptions of the domestic refrigerator-freezers using the spiral fin-tube evaporators with N = 11 and 13 were 2.8% and 1.5% lower than those using the plate fin-tube evaporator, respectively. In addition, the cooling capacity of the spiral fin-tube evaporator with N = 13 was 3%-7% higher than that of the plate fin-tube evaporator under the frosting condition. In a cooling speed test, all of the evaporators showed similar performances.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.8
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• pp.99-107
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• 2010

In a single frequency network (SFN) for Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) system, the interferences induced by the multiple transmitters and/or repeaters using the same frequency are inevitable. Since the presence of interferences results in performance degradation of the SFN, it is crucial to manipulate the interferences by adjusting the transmit power and timing of each transmitter and repeater. In the ATSC terrestrial DTV system, in order to facilitate the interference manipulation process, a transmitter identification (TxID) signal which is uniquely embedded in the signal to be transmitted from each transmitter and repeater is recommended. Even though the injection level of the TxID signal is much lower than the DTV signal, the TxID signal injection infects the DTV signal. Hence, the effect of the TxID signal on the DTV signal must be investigated before deployment. In this paper, the effect of the TxID signal on the performance of legacy DTV receivers under additive white Gaussian noise and multipath channel environments is investigated not only with computer simulation but also with laboratory and field tests. The test results show that the average threshold of visibility degradation of the legacy DTV receivers due to the TxID signal injection is less than 0.2 dB at the TxID injection level of -30 dB.

• Journal of Advanced Marine Engineering and Technology
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• v.8 no.1
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• pp.17-36
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• 1984

Since 1973, the competition on the development of fuel saving type internal combustion engines has become severe by the two times oil shock, and new type engines are reported every several months. Whenever these new type engines are developed, new designs are required and they will be offered in the market after performing the endurance test for a long time. But the engine market is faced with a heavy burden of finance, as the developing of a new engine requires tremendous expenses. For this reason, the computer simulation method has been lately developed to cope with it. The computer simulation method can be available to perform the reasonable research works by the theoretical analysis before carrying out practical experiments. With these processes, the developing expenses are cut down and the period of development is curtailed. The object of this study is the development of simulation computer program for the small naturally aspirated four-stroke diesel engine which is intended to product by the original design of our country. The process of simulation is firstly investigated for the ideal engine cycle, and secondly for the real engine cycle. In the ideal engine cycle, each step of the cycle is simulated by the energy balance according to the first law of thermodynamics, and then the engine performance is calculated. In the real cycle imulation program, the injection rate, the preparation rate and the combustion rate of fuel and the heat transfer through the wall of combustion chamber are considered. In this case, the injection rate is supposed as constant through the crank angle interval of injection and the combustion rate is calculated by the Whitehouse-Way equation and the heat transfer is calculated by the Annand's equation. The simulated values are compared with measured values of the YANMAR NS90(C) engine and Mitsubishi 4D30 engine, and the following conclusions are drawn. 1. The heat loss by the exhaust gas is well agree with each other in the lower load, but the measured value is greater than the calculated value in the higher load. The maximum error rate is about 15% in the full load. 2. The calculated quantity of heat transfer to the cooling water is greater than the measured value. The maximum error rate is about 11.8%. 3. The mean effective pressure, the fuel consumption, the power and the torque are well agree with each other. The maximum error is occurred in the fuel consumption, and its error rate is about 7%. From the above remarks, it may be concluded that the prediction of the engine performance is possibly by using the developed program, although the program needs to reform by adding the simulation of intake and exhaust process and assumping more reliable mechanical efficiency, volumetric efficiency, preparation rate and combustion rate.

• Management & Information Systems Review
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• v.2
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• pp.47-73
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• 1998

According to the structural contingency theories, organizational structures are determined by such a contingency variables as organizational environment, technology, size, power and strategy. Therefore, many scholor believed that organizational effectiveness will be maximized in the condition of the fit between organizational structure and its contingency variables. But contingency theories have limitations in explaining of the manager's discretion by way of environmental determinism. In 1972, Child introduced strategic choice theory, and this perspective spurred significant, systematic studies of the influence of the managerial voluntary will on the organizational performance. Especially, the question of whether tap managers have an impact on business performance has been addressed by the strategic leadership theory that demonstrates strong associations between the characteristics of top managers, strategic orientation. Therefore, this study has investigated a theoretical literature and an empirical survey that explains the impact of top manger characteristics and organizational characteristics about strategic orientation. In order tn do that, this study develops a research model on the subjects, designed manager's characteristics, strategic typology. Managerial characteristics could be operationalized in terms of demographic measures. In this study, strategic orientation was classified using the Miles & Snow typology. This research model provides hypotheses. Hypotheses H1: The demographic characteristics of the tap manager will differ according to the types of strategic types. H2: The organizational characteristics of the firm will differ according to the types of strategic types. To test these hypotheses, this study conducted questionaire surveys on 108 firms in the Korea national wide. This study has utilized ANOVA, Chi-square analysis, cluster analysis, discriminant analysis for testing the hypotheses. The major findings of this study are summarized as follows. First, this study builds on the central tenent of cotingency theory in provide a comprehensive explanation of the process by which top manager's influence. Second, Manager's characteristics(demographics) are different from each other according to 4 strategic types(Prospector, Defender, Analyzer, Reactor). Third, Organizational characteristics are different from each other according to 4 strategic types. In conclusion, the major contributions of this study are to examine the development of a more comprehensive theoretical framework in the strategic leadership theory and to analyze their contingent relationships among managerial characteristics, organizational characteristics and strategic types in the context of Korea's industry.

• The Journal of the Acoustical Society of Korea
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• v.23 no.2
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• pp.180-186
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• 2004

The presence of noise in speech signals degrades the performance of recognition systems in which there are mismatches between the training and test environments. To make a speech recognizer robust, it is necessary to compensate these mismatches. In this paper, we studied about an improvement of stochastic feature extraction based on band-SNR for robust speech recognition. At first, we proposed a modified version of the multi-band spectral subtraction (MSS) method which adjusts the subtraction level of noise spectrum according to band-SNR. In the proposed method referred as M-MSS, a noise normalization factor was newly introduced to finely control the over-estimation factor depending on the band-SNR. Also, we modified the architecture of the stochastic feature extraction (SFE) method. We could get a better performance when the spectral subtraction was applied in the power spectrum domain than in the mel-scale domain. This method is denoted as M-SFE. Last, we applied the M-MSS method to the modified stochastic feature extraction structure, which is denoted as the MMSS-MSFE method. The proposed methods were evaluated on isolated word recognition under various noise environments. The average error rates of the M-MSS, M-SFE, and MMSS-MSFE methods over the ordinary spectral subtraction (SS) method were reduced by 18.6%, 15.1%, and 33.9%, respectively. From these results, we can conclude that the proposed methods provide good candidates for robust feature extraction in the noisy speech recognition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.618-624
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• 2017

In Seoul and most metropolitan cities, urban trains are delayed due to high congestion during commute times. The delay effect of passengers boarding and disembarking is also significant. In this study, a wide passenger door system was developed as a way to improve the scheduled speed of urban trains by decreasing the passengers' flow time. The door size was defined experimentally to shorten the entrance time. The optimum door size was also determined to improve the stop precision performance of the train while considering the interference effect with peripheral devices. Because the change in door size changes the structural characteristics of the vehicle, the structural stability of a train was analyzed numerically. A prototype of the wide door system was made, and the proposed design was verified using functional and endurance tests. The systematic development process can be used as design data for door size definition and system production when applying a wide door to improve the scheduled speed.