• Tribology and Lubricants
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• 제35권4호
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• pp.215-221
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• 2019

A gerotor set consists of two elements, an inner rotor and an outer rotor. The outer rotor has one more tooth than the inner rotor and has its centerline positioned at a fixed eccentricity from the centerline of the inner rotor. Although gerotors come in a variety of geometric configurations, all gerotor sets share the basic principle of having generated tooth profiles that provide continuous tight sealing during operation. The size of the gerotor is proportional to the number of teeth and the amount of eccentricity. The interior of an inner rotor with a large number of teeth has an enough space to include other machine elements. In this paper, the double gerotor mechanism, constructed by putting a small gerotor in the interior of a large inner rotor, is conceptualized. The double gerotor set is composed of an inner rotor, a planetary rotor, and an outer rotor. The inside profile of the planetary rotor corresponds to the outer rotor profile of the small gerotor, and the outside profile is the inner rotor profile of the large gerotor. In the double gerotor, the centers of the inner and the outer rotor are coincident because the eccentricities of two gerotors are balanced. The operation of a double gerotor is examined by analyzing the planetary motion, and a feasibility study for application of the double gerotor for hydraulic motors and pumps is performed. The double gerotor set has much application potential as a component of hydraulic systems.

• 한국항해항만학회지
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• 제36권4호
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• pp.273-278
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• 2012

This study is concerned with the applicable countermeasures for securing safety of ship from piracy attacks. For improvements and countermeasures, we analyzed the recent anti-piracy trends. In spite of international community's various activities for safety navigating, the number of piracy in Gulf of Aden and in the vicinity of Somali waters has been increasing dramatically in the last few years, so has the number of piracy on Korean vessels. In case of piracy attack which based on Somalia, it continues constantly and widely not only near shore, but coastal and oceanic waters. This study figures out the limitations of international community's efforts including military and legal improvements. There are no studies concerning the countermeasures of bridge protection by piracy. This study suggested the additional installation of outside door of bridge as well as the adjustment of piracy operation area(POA) of Korea navy.

• 전기학회논문지
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• 제67권5호
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• pp.680-687
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• 2018

Because of its predictability of the energy cycle and huge scale power output, the ocean energy from tidal power utilization has always received attention as a great energy source, even though its development cost, including the embankment construction, is so much higher than that of any other energy source. Nevertheless, nowadays many projects are being planned on account of institutional support from the government and the recent advance of construction technology. In Korea, the new industry field operating and managing the tidal power plant has already opened. But we are facing a number of problems for optimal operation of tidal power plant that are a lack of operation experience and a skill of professional management and others. This paper suggests a novel way to determine the starting head of power generation by generating power comparison method For this new method, the paper discusses many factors including changing the volume of the basin, the number of operating turbines and gates and forecasting the tidal amplitude and the characteristic curve of turbine and gate. Finally we verified that it can increase about 2% an annual power generation compared with the conventional method using the original operational function made in the plant design process.

• 보건행정학회지
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• 제8권2호
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• pp.88-109
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• 1998

The main purpose of this study is to compare the traditional cost system and ABC(Activity Based Cost) system of clinical laboratory department in a hospital. The study subject was 296 services in clinical laboratory from March, 1997 to August, 1997. In a new costing system, cost for a lab test consist of direct cost element, activity based cost element, and allocated common cost element. In a traditional cost system, cost elements included direct cost element and indirect cost allocated based on test volumes The major findings of this research were as follows. 1. In the application of ABC system, total cost was analyzed as follows. Direct cost was 39.3% of total cost. Activity cost and allocation were 20.9% and 39.8%, respectively. The results of analysis to use traditional cost system were as follows. Direct cost was 39.3% and it was as same as the result of direct cost of ABC system. Indirect cost was 60.7%. 2. Activities of clinical laboratory of subject hospital were registration, pre-test operation, test, test result handling, delivery, culture, post-test operation, technical support, management support, and educational support. 3. The differences of the case of higher number of test case being carried out, the cost of ABC system was lower than the cost of traditional cost system. Otherwise in the case of lower number of test case being carried out, the rests have not been appropriately evaluated, and effective management were needed in clinical laboratory.

• 한국식생활문화학회지
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• 제15권2호
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• pp.69-78
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• 2000

The purposes of this study were to : (a) investigate overall operating conditions of university residence hall foodservice, (b) compare them by the management systems. Questionnaires were hand delivered and mailed to 73 foodservice managers. A total of 56 were usable; resulting in 76.7% response rate. The survey was conducted between October, 1998 and May, 1999. Statistical data analysis was completed using the SAS/Win 6.12 for Descriptive Analysis, $x^2-test$. Sixty-four percent of the foodservice operations were 'self-operated'; 23% were 'contracted'; and 13% were 'rented'. Eighty-three percent of operations provided 'single menu'; forty-six percent of foodservice operations with 'partially self-service'; and forty-one percent with 'complete self-service'. Forty-four percent of overall foodservice operations provided 1,000-2,000 meals per day; thirty-one percent provided less than 1,000 meals per day, and twenty-four percent provided more than 2,000 meals per day. The highest meal price was 1,950 won and the lowest was 700 won with average of 1,295 won. The mean number of employees was 12.2; the number of working hours was 59.7 hours per week.

• 상하수도학회지
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• 제23권3호
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• pp.271-276
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• 2009

Under current design standard, sewers are designed to drain stormwater generated up to 10 year return period of storms. This implies sewer flooding could occur from rainfall exceeding a 10 year return period. 5, 10, 20 and 30 year return period of storm intensities were calculated for 22 locations (cities) of meterological stations over the nation and compared to the recorded rainfall intensities for the last 30 years. The comparison resulted in the numbers of year maximum rainfall intensities exceeded each return period. Using the questionnaire survey for "the incidences of flooding since 1980" of the previous paper (Survey on sewerage operation/management planning for flooding (I)), the actual rainfall records on the date of flooding events were analyzed to demonstrate the number of flooding events caused by the exceedance of sewer capacity. For the last 30 years, more than 6 years of year maximum rainfall intensity (20%) were larger than the 10 year return period of storm in 4 cities of the 22 used for the first analysis. The number of rainfall records that exceeded the 10 year return period was 50 of the 260 actual flooding events investigated from the survey.

• 한국항만학회지
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• 제1권1호
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• pp.21-47
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• 1987

Nowaday all the countries of the world have studied the various problems caused in operating their own ports efficiently. Ship delay in the port is attributal to the inefficient operation in the navigation aids, the cargo handling, the storage and transfer facilities, and to the inefficient allocation of gangs or to a bad service for ships. Among these elements the allocation of gangs is the predominating factor in minimizing ship's turn round time. At present, in the case of Pusan Port. the labour union and stevedoring companies allocate gangs in every hatches of ships by a rule of thumb, just placing emphasis on minimizing ship's turn round time, without applying the principle of allocation during the cargo handling. Owing to this the efficiency of the cargo handling could not be expected to be maximized and this unsystematic operation result in supplying human resources of much unnecessary surplus gangs. Therefore in this paper the optimal size and allocation of gangs for minimizing the ship's turn round time is studied and formularized. For the determination of the priority for allocation the evaluation function, namely $F=PHi^{n}{\times}(W+H)$, can be obtained; where, PHI : Principal Hatch Index W : Total Cargo Weight represented in Gang-Shifts H : Total Number of Ship's hatches and also for the optimal size of gangs the average number of gang allocated per shift (Ng), namely Ng=W/PHI, is used. The proposed algorithm is applied to Pusan Port and its validity is verified.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제49권3호
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• pp.135-141
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• 2023

Objectives: This study aimed to develop and validate machine learning (ML) models using H₂O-AutoML, an automated ML program, for predicting medication-related osteonecrosis of the jaw (MRONJ) in patients with osteoporosis undergoing tooth extraction or implantation. Patients and Methods: We conducted a retrospective chart review of 340 patients who visited Dankook University Dental Hospital between January 2019 and June 2022 who met the following inclusion criteria: female, age ≥55 years, osteoporosis treated with antiresorptive therapy, and recent dental extraction or implantation. We considered medication administration and duration, demographics, and systemic factors (age and medical history). Local factors, such as surgical method, number of operated teeth, and operation area, were also included. Six algorithms were used to generate the MRONJ prediction model. Results: Gradient boosting demonstrated the best diagnostic accuracy, with an area under the receiver operating characteristic curve (AUC) of 0.8283. Validation with the test dataset yielded a stable AUC of 0.7526. Variable importance analysis identified duration of medication as the most important variable, followed by age, number of teeth operated, and operation site. Conclusion: ML models can help predict MRONJ occurrence in patients with osteoporosis undergoing tooth extraction or implantation based on questionnaire data acquired at the first visit.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 추계학술대회
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• pp.70-72
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• 2019

For the safe and reliable operation of Lithium-ion batteries in Electric Vehicles (EVs) or Energy Storage Systems (ESSs), it is essential to have accurate information of the battery such as State of Charge (SOC). Many kinds of different techniques to estimate the SOC of the batteries have been developed so far such as the Kalman Filter. However, when it is applied to the multiple number of batteries it is difficult to maintain the accuracy of the estimation over all cells due to the difference in parameter value of each cell. Moreover the difference in the parameter of each cell may become larger as the operation time accumulates due to aging. In this paper a novel Deep Neural Network (DNN) based SOC estimation method for multi cell application is proposed. In the proposed method DNN is implemented to learn non-linear relationship of the voltage and current of the lithium-ion battery at different SOCs and different temperatures. In the training the voltage and current data of the Lithium battery at charge and discharge cycles obtained at different temperatures are used. After the comprehensive training with the data obtained with a cell resulting estimation algorithm is applied to the other cells. The experimental results show that the Mean Absolute Error (MAE) of the estimation is 0.56% at 25℃, and 3.16% at 60℃ with the proposed SOC estimation algorithm.

• 정보와 통신
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• 제4권4호
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• pp.505-524
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• 1987

Nowaday all the countries of the world have studied the various problems caused in operating their own ports efficiently. Ship delay in the port is attributal to the inefficient operation in the navigation aids, the cargo handling, the storage and transfer facilities, and to the inefficient allocation of gangs or to a bad service for ships. Among these elements the allocation of gangs is the predominating factor in minimizing ship's turn round time. At present, in the case of Pusan Port. the labour union and stevedoring companies allocate gangs in every hatches of ships by a rule of thumb, just placing emphasis on minimizing ship's turn round time, without applying the principle of allocation during the cargo handling. Owing to this the efficiency of the cargo handling could not be expected to be maximized and this unsystematic operation result in supplying human resources of much unnecessary surplus gangs. Therefore in this paper the optimal size and allocation of gangs for minimizing the ship's turn round time is studied and formularized. For the determination of the priority for allocation the evaluation function, namely $F=PHi^{n}{\times}(W+H)$, can be obtained; where, PHI : Principal Hatch Index W : Total Cargo Weight represented in Gang-Shifts H : Total Number of Ship's hatches and also for the optimal size of gangs the average number of gang allocated per shift (Ng), namely Ng=W/PHI, is used. The proposed algorithm is applied to Pusan Port and its validity is verified.