• Journal of the Korean Institute of Gas
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• 제26권2호
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• pp.21-26
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• 2022

Since the four-wheel drive transmits the driving force to all four wheels, the traction with the road surface increases, thereby increasing the driving force. However, it has the disadvantage of lowering fuel efficiency. Therefore, four-wheel drive is commonly used as a method of converting to optional four-wheel drive when necessary while driving in two-wheel drive. This selective four-wheel drive converts the driving force by mechanically changing the electric signal sent by the driver in the transfer case. In this study, in order to mechanically change the electrical signal, a reducer is applied to the motor to increase the torque to perform the function. Therefore, in this study, a reduction mechanism applicable to the motor inside the transfer case applied to convert the drive is derived, and the reduction ratio applying the planetary gear type is optimized accordingly. And based on the derived reduction ratio, two sets of planetary gears using a ring gear in common were applied to develop a planetary gear tooth type in which the input shaft and output shaft are decelerated in the same phase. Optimization design was carried out.

• Journal of Legislation Research
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• 제44호
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• pp.343-386
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• 2013

"Financial ADR" system in South Korea can be represented by so-called "Financial Dispute Resolution System", in which Financial Supervisory Service (FSS) and Financial Dispute Resolution Committee are the principal actors in operation of the system, and this is discussed as an "Administrative Financial ADR System". The system has over 10-year history since it was introduced in around 1999. Nonetheless, it was not until when financial consumer protection began to be highlighted after the 2008 financial crisis that Financial ADR system actually started to draw attention in Korea. This was because interest has been rising in "Alternative Dispute Resolution (ADR)" as an institutional measure to protect financial consumers damaged via financial transactions. However, the current discussion on the domestic Financial ADR system shows an aspect that it is confined to who is to be a principal actor for the operation of Financial ADR institution with main regards to reorganization of supervisory system. This article aims to embody these facts in an institutional model by recognizing them as a problem and analyzing the features of the Financial ADR system, thereby clarifying problems of the system and presenting the direction of improvement. The Korean Financial ADR system can be judged as "administrative model integrated model consensual model quasi-judicial model non-prepositive Internal Dispute Resolution (IDR) model". However, at the same time, it is confronted with a task to overcome the two problems; the system is not equipped with institutional basis for securing its validity in spite of the adopted quasi-judicial effect model; and a burden of operating an integrated ADR system is considerable. From this perspective, the article suggests improvement plans for security of validity in the current system and for expansion of industry-control ADR system, in particular, a system of prepositive IDR model. Amongst them, it suggests further plans for securing the validity of the system as follows; promotion to expand the number of internal persons and to differentiate mediation procedures and effect; a plan to keep a financial institution from filing a lawsuit before an agreement recommendation or a mediation proposal is advised; and a plan to grant suspension of extinctive prescription as well as that of procedures of the lawsuit.

• Korean Chemical Engineering Research
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• 제49권5호
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• pp.644-651
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• 2011

Storing hydrogen in solid state hydride is one of the best promising methods for the future hydrogen economy. The total performance of such systems depends on the rate at which the amount of mass and heat migration is supplied to solid hydride. Therefore, an accurate modeling of the heat and mass transfer is of prime importance in optimizing the design of such systems. In this work, Hydrogen storage in Pt-CNTs hydrogen reactor has been intensively investigated by solving 2 dimensional mathematical models. Using a CFD computer software, systematic studies have been performed to elucidate the effect of heat and mass transfer during hydrogen charging periods. It was revealed that the optimized design of hydrogen storage vessel can prevent the increase of system temperature and the charging time due to the convective cooling effects inside the vessels at even high charging pressure. Because none has reported the critical issues of heat and mass transfer for CNT based hydrogen storage system, this work can support the first insight of the optimal design for solid state hydrogen storage system based on CNT in the near future.

• Journal of Drive and Control
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• 제17권1호
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• pp.1-12
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• 2020

This study was to develop a simulation model of a compound planetary gear reducer for the final driving shaft using a gear analysis software (KISSsoft, Version 2017, KISSsoft AG, Switzerland). The aim of this study is to analyze transmission error and the tooth load distribution through micro-geometry using the simulation model. The tip and root relief were modified with Micro-geometry in the profile direction, and crowning was modified with Micro-geometry in the lead direction. The transmission error was analyzed using the PPTE (Peak to Peak Transmission Error) value, and the tooth load distribution was analyzed for the concentrated stress on the tooth surface. As a result of modifying tip and relief in the profile direction, the transmission error was reduced up to 40.7%. In the case of modifying crowning in the lead direction, the tooth load was more evenly distributed than before and decreased the stress on the tooth surface. After modifying the profile direction for the 1st and 2nd planetary gear train, the bending and contact safety factors were increased by 31.7% and 17%, and 18.3% and 12.5% respectively. Moreover, the bending and safety factors after modifying lead direction were increased by 59.5% and 32.7%, respectively for the 1st planetary gear train, and 59.6% and 43.6%, respectively for the 2nd planetary gear train. In future studies, the optimal design of a compound planetary gear reducer for the final driving shaft is needed considering both the transmission error and tooth load distribution.

• The Journal of Korean Orthopaedic Ultrasound Society
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• 제8권1호
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• pp.1-5
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• 2015

Purpose: The purpose of this study was to analyze the effectiveness of local steroid injection for infraspinatus under ultrasonographic guidance in patients with posterior shoulder pain during horizontal adduction test. Materials and Methods: Twenty one cases of patients, from May 2013 to May 2014, showed positive horizontal adduction test were retrospectively analyzed. We performed ultrasonography-guided infraspinatus injection using steroid to these patients in the outpatient clinics. We evalulated results for visual analogue score (VAS) for pain, UCLA score for these patients before injection, following 3 months and 6 months after injection. Results: After ultrasonography-guided infraspinatus injection using steroid, there were clinically significant improvements in VAS and UCLA score at 3 month's follow-up period (p<0.05). But there were no significant differences in VAS and UCLA score between 3 months and 6 months (p>0.05). Fourteen of 21 (67%) cases showed much improved and improved satisfaction. Respectively, seven of 21 (33%) cases showed not improved and aggravation satisfaction. Conclusion: Ultrasonography-guided infraspinatus injection using steroid is an effective treatment method for the patients with exacerbated posterior shoulder pain during horizontal adduction test.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2008년도 추계 학술발표회 제20권2호
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• pp.641-644
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• 2008

This paper investigated the plant and raw material of the ready-mixed concrete company which could supply to the second Lotte World on Pusan. the results were summarized as following. Almost plants were mainly using Twin shaft mixer which was 210m$^3$/hr and horizontal type. There was different the number of admixture silos at each plants, and they were separated by types. The mixtures mainly consisted of the ordinary portland cement, fly ash and blast furnace slag. For favorable quality control, each materials had to carry from same factories, and the monitering standard for quality control should be prepared. The coarse aggregates were used with many different producing districts, so they were only used from Y caused by exclusion of quality difference. The crushed, washed and river sands were generally used as fine aggregates, so the fine aggregates which could be possible to supply stable quality were chosen. This study used Poly Carbonic Acid Admixture which was developed to satisfy maintenance of performance till 2 hours and 10MPa at 15 hours.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제35권8호
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• pp.847-853
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• 2011

In this study, a hybrid powder-extrusion process involving the control of temperature dwelling time for improving the formability of Zn-22Al powder was developed and the effect of dwelling time on the mechanical properties of a spur gear with a pitch circle having a diameter of 1.8 mm was investigated. General extrusion experiments were carried out at different temperatures such as 290, 300, and $310^{\circ}C$. Spur gears with good qualities and without any surface defects were obtained in the case of extrusion temperature of $310^{\circ}C$ and ball-milling duration of 32 h. The Vickers hardness distribution was non-uniform, and after the sintering process, an internal crack was generated because of the different deformation energy between gear central part and teeth. To overcome the abovementioned problems, research on controlling the dwelling time of the extrusion temperature in the powder-extrusion process was carried out. Good-quality spur gears were obtained when the dwelling time was 15 min.

• Journal of the korean academy of Pediatric Dentistry
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• 제38권1호
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• pp.75-81
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• 2011

Supernumerary teeth are in excess of the normal number of teeth in either the primary or permanent dentitions. They are classified into supplemental teeth resembling those of the normal series and rudimentary teeth with abnormal shapes, according to their form. Most of the supernumerary teeth are rudimentary form, and supplemental teeth are much less common. Sulppemental teeth are most common in the permanent maxillary lateral incisor area and clinicians should be careful with differential diagnosis from normal teeth. Unerupted supernumerary teeth may produce several complications such as delayed eruption, displacement of permanent teeth, diastema, root resorption and cyst formation. Early detection and proper treatment plan according to the tooth alignment and root formation stage are important. Here we report 3 cases of unilateral or bilateral normal incisor shaped supernumerary lateral incisors treated by eruption observation, surgical extraction and orthodontic treatment with resin build-up.

• KDI Journal of Economic Policy
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• 제14권2호
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• pp.155-187
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• 1992

The Korean economy has sustained high growth rate for almost three decades, that have been associated with the rapid expansion of manufacturing industries. In the beginning stage of development, the high growth of the Korean economy has been based on improvements in productivity obtained by the economies of scale. In that period, the improvements in productivity could be secured by the economies of scale in the export-oriented industries which are the labor- and material-intensive industries. In the latter half of the 1980s, the Korean economy went through rapid transition. Now Korea is at another juncture in its development process, where economic restructuring is critical to sustain high growth. However, economic restructuring in the 1990s call for much more concerted effort than before, since changes in internal and external conditions have profoundly altered the environment for economic development. If Korea is to sustain high growth in the 1990s, it has to promote balanced economic and social development in coordination with the smooth facilitation of industrial restructuring. There are no inherent conflicts among the issues involved, so they can be resolved by restructuring the economy to facilitate, in a global context, the development of knowledge- and technology-intensive activities and to ensure that the benefts of growth are reflected of qualitative improvements in national living standards. In this paper, we examined a scenario of structural changes using a mid- and long-term multisector model, in order to understand the conditions needed for realizing the growth potential. This examination explains the important features of the development course and policy directions that will help sustain high growth in the 1990s.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제40권12호
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• pp.1005-1011
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• 2016

The fundamental reason for gear noise is transmission error. Transmission error occurs because of STE (static transmission error) and DTE (dynamic transmission error), while a pair of gears is meshing. These errors are generated by the deflection of the teeth and the friction on the surface of the teeth. In addition, the vibration generated by transmission error leads to excited bearings. The bearings support the shafts, and the noise is radiated after exciting the gear casing. The analysis of the contact stress in helical gear tooth flanks indicates that it is due to impact loading, such as the sudden engagement and disengagement of a gear. Stress analysis is performed for different roll positions, in order to determine the most critical roll angle. Dynamic analysis is performed on this critical roll position, in order to evaluate variation in stresses and tooth contact force, with respect to time. In this study, transmission error analysis was implemented on a spur and helical gear with involute geometry and a modified geometry profile. In addition, in order to evaluate the intensity of impact due to sudden engagement and significant backlash, the impact factor was calculated using the finite element analysis results of static and dynamic maximum bending stresses.