• Journal of Technology Innovation
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• v.12 no.3
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• pp.159-177
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• 2004

Technological innovation is one of the critical success factors determining firm's Technological innovation is one of the critical success factors determining firm's value in the knowledge based economy. The study examines whether the information release on technological innovation has information contents in the stock market. The abnormal returns and cumulative abnormal return were calculated by using Market and Risk Adjusted Return Model. The results say that the market positively reacts to the information release of technological innovation on the event date. Especially, the disclosure on technology development causes stable increase of the firm's value. It is concluded that the market reacts favorably to technological innovations.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.1-8
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• 2024

This paper employs stochastic processing techniques to analyze explosion risks in plant facilities based on explosion return periods. Release probability is calculated using data from the Health and Safety Executive (HSE), along with annual leakage frequency per plant provided by DNV. Ignition probability, derived from various researchers' findings, is then considered to calculate the explosion return period based on the release quantity. The explosion risk is assessed by examining the volume, radius, and blast load of the vapor cloud, taking into account the calculated explosion return period. The reference distance for the design blast load model is determined by comparing and analyzing the vapor cloud radius according to the return period, historical vapor cloud explosion cases, and blast-resistant design guidelines. Utilizing the multi-energy method, the blast load range corresponding to the explosion return period is presented. The proposed return period serves as a standard for the design blast load model, established through a comparative analysis of vapor cloud explosion cases and blast-resistant design guidelines. The outcomes of this study contribute to the development of a performance-based blast-resistant design framework for plant facilities.

• Journal of Korean Neurosurgical Society
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• v.37 no.1
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• pp.8-15
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• 2005

Objective: We evaluate temporal correlations between postoperative symptomatic and electrophysiological improvements, and assessed the recovery time required for patients with carpal tunnel syndrome(CTS) before returning to routine activities. Methods: 30 CTS patients were treated via the endoscopic monoportal approach, from March 2001 to September 2003. We assessed the symptoms (hyperesthesia in the finger tips, or abnormal sensations and painful numbness or night pain) and electrophysiological changes in the preoperative state, 1 month and 6 months after surgery. We marked the times at which patients became able to return to activities of daily living and work, after undergoing endoscopic carpal tunnel release. Results: At the end of the follow-up period, high levels of achievement and good outcomes were observed, with respect to both the symptoms and electrophysiological studies. We discovered significant differences between the preoperative and postoperative periods, especially in terms of motor nerve onset latency from $4.50{\pm}1.43$ to $3.97{\pm}0.69$ and sensory nerve conduction velocity, the wrist-to-finger from $19.81{\pm}10.03$ to $28.18{\pm}11.01$ and wrist-to-palm from $23.34{\pm}13.40$ to $31.79{\pm}13.38$(P<0.05 for each comparison). The average time interval required before return to activities of daily living was 26.4 days, and time interval required before return to work was 48.08 days. Conclusion: Electrophysiological improvements are largely consistent with symptomatic relief, but there is some disparity between electrophysiological and symptomatic improvement.

• Journal of Korean Society on Water Environment
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• v.18 no.2
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• pp.123-130
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• 2002

Bench scale experiments were carried out with two biological nutrient removal(BNR) units, A/O and $A^2O$ processes, to investigate the behavior of phosphorus in the system and to compare the characteristics of phosphorus removal in two BNR processes. To achieve this goal, COD/T-P and COD/TKN ratios of the influent was varied in the range of 23~64 and 5~24, respectively. In A/O process, influent COD/T-P ratio should be kept higher than 44mg/L to meet the final effluent T-P concentration lower than 1mg/L and in $A^2/O$ process, influent COD/T-P and COD/TKN ratios higher than 56 and 10, respectively, were required for good phosphorus release and uptake with no influence of nitrate nitrogen in return sludge. At this conditions, the rate of phosphorus release in the anaerobic basin should be kept higher than 0.1 kg S-P/kg MLVSS d In A/O process, the phosphorus content of anaerobic and aerobic sludges was increased as SRT of total system was becoming longer resulting in decreasing the difference of phosphorus content between two sludges while phosphorus release in anaerobic basin and phosphorus uptake in aerobic basin was not incident. In $A^2/O$ process, the phosphorus content of anaerobic and aerobic sludges were not increased with higher SRT of total system due to the relatively high nitrate concentration in return sludge. However, the difference of phosphorus content between anaerobic and aerobic sludges was incident when phosphorus release and uptake was observed.

• 대한관절경학회:학술대회논문집
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• 2006.11a
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• pp.35-39
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• 2006

Posterior capsular tightness with glenohumeral internal rotation deficit is usually considered to be an acquired condition of the throwing shoulder and is usually treated conservatively. However, because posterior capsular tightness is sometimes irreversible, we have performed arthroscopic capsular release for painful throwing shoulder with posterior capsular tightness. The true loss of internal rotation and posterior stiffness was confirmed by examination with the patient under anesthesia, and contracture of the posterior capsule and the posterior band of the inferior glenohumeral ligamant was observed arthroscopically. Because an extensive adhesion between the capsule and the fascia of the external rotators was noted, a capsular release was performed from 6 o'clock to 11 o'clock (in the right shoulder) to completely expose the muscle belly of the external rotators. Of the first 16 consecutive patients, 4 had no concomitant lesions and underwent posterior capsular release alone. With a minimum of 2 years' follow-up, it was ascertained that the throwing pain completely disappeared in 14 patients and improved in 2. In all, 11 patients returned to their preinjury performance level, and 5 returned to a lower level of function. In the 4 patients who had no concomitant lesions, throwing pain completely disappeared, and all were able to return to their preinjury performance level.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.164-170
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• 2008

A typical clutch system for automotive manual transmissions transfers hydraulic pressure generated by driver's pedal manipulation to the clutch diaphragm spring. The foot effort history during the period of push is different than the period of the clutch pedal's return. The effort or load difference is called clutch foot effort hysteresis. It is known that the hysteresis is caused by friction. The frictional force and moment are produced between various component contact points such as between the rubber seal and the inner wall inside the hydraulic cylinder and between the diaphragm spring and the pressure plate, etc. Understanding the clutch pedal foot effort hysteresis is essential for a clutch release system design and analysis. The dynamic model for a clutch release system is developed for the foot effort hysteresis prediction and a simulation analysis is performed to propose a tool for analysing a clutch system.

• Journal of Biosystems Engineering
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• v.39 no.4
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• pp.267-273
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• 2014

Purpose: This study was conducted to develop a web-based business management system to ensure the efficient operation and transparent management of government-subsidized agricultural machinery rental businesses. Methods: An MS_SQL2000 database management system (DBMS) solution was utilized in the system for high system compatibility and integrated management. This system was targeted to be compatible with Internet Explorer 6.0 or later and to ensure security and seamless web operations. The system administrator is able to manage a fleet of agricultural machinery, including various inventory codes, release and return, fleet registry, and business performance. Users (farmers) may search the database of rental machinery and reserve them. Results: With respect to rental reservations, the system administrator can manage the fleet by setting the rental status to Approved, Released, or Returned. Through the web, the administrator can also create a database that includes machinery specifications, features, and rental rates. In addition, business performance data can be analyzed using a diverse array of tools to streamline the rental business. Without having to go to the rental office, users can save time and money by searching for and renting agricultural machinery through the information available on the website, including availability, specifications, and rental fees. After deploying the system, the time required to analyze monthly performance and create reports was dramatically reduced from 20 days per person to one day per person. Conclusions: Since 2014, AMRB has been installed and is operating in agricultural machinery rental businesses in 31 cities and counties in South Korea. This study recommends continued expansion and dissemination of AMRB for the systematic and efficient management of agricultural machinery rental businesses.

• Journal of the Korea Society of Computer and Information
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• v.29 no.2
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• pp.51-59
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• 2024

This study examines the relationship between the release of the news and the individual stock returns. Investors utilize a variety of information sources to maximize stock returns when establishing investment strategies. News companies publish their articles based on stock recommendation reports of analysts, enhancing the reliability of the information. Defining release of a stock-recommendation news article as an event, we examine its economic impacts and propose a binary classification model that predicts the stock return 10 days after the event. XGBoost and LightGBM models are applied for the study with accuracy of 75%, 71% respectively. In addition, after categorizing the recommended stocks based on the listed market(KOSPI/KOSDAQ) and market capitalization(Big/Small), this study verifies difference in the accuracy of models across four sub-datasets. Finally, by conducting SHAP(Shapley Additive exPlanations) analysis, we identify the key variables in each model, reinforcing the interpretability of models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.61-65
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• 2005

We propose a soft QoS-based borrowing scheme for call admission control(CAC) in DVB-RCS(Digital Video Broadcast-Return Channel via Satellite). Some of the ongoing calls temporarily and fairly release bandwidths that can be used to accommodate a new call in an overloaded satellite network. The amount of bandwidth borrowed from each call is proportional to each user's critical bandwidth ratio, one of parameters for soft QoS mechanism. Simulation results show that the proposed scheme improves the system performance in terms of call blocking probability and bandwidth utilization.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.664-668
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• 2005

An experimental study for the comparison of nitrogen and phosphorus removal efficiencies between $A^2/O$ and modified Phostrip (M-Phostrip process) were carried out with bench-scale reactors. In case of nitrogen removal efficiencies both of processes showed similar ones when influent organic loadings were high. However, M-phostrip process was more effective than $A^2/O$ at low organic loadings. This is why M-phostrip process consumes the whole mass of influent organics as a carbon sources for denitrification in anoxic reactor but the anoxic reactor of $A^2/O$ process utilizes the residual carbon followed by consumming a part of influent carbon for phosphorus release in anaerobic reactor. $A^2/O$ process required the influent COD/T-P and COD/TKN ratios were more than 56 and 10, respectively, to take place the phosphorus release in anaerobic process and phosphorus uptake in oxic process. However, the luxury uptake of phosphorus in M-phostrip process was not affected by influent COD/T-P and COD/TKN ratios and the adverse effect of nitrate in return sludge introduced to the p-stripper from the 2nd clarifier was not significant due to the configurational advantage of the p-stripper.