• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.3
• /
• pp.174-181
• /
• 2012

The spindle unit is a core part in high precision machine tool. Rotation accuracy of spindle unit is needed for high dignity cutting and improving the performance of machine tool. However, there are many factors to effect to rotational error motion(rotation accuracy). This study studied how rotational error motion is variation when unbalance amount is variation. Rotation accuracy of initial spindle unit is decided depending on parts and assembly such as bearing. When it is rotation, vibration and noise is appeared depending on volume of unbalance amount, so it works to decrease unbalance amount. The purpose of the study tests that unbalance amount how much effects to initial rotation condition. The result of the study shows that accuracy of parts and assembly is highly necessary to reach high rotation accuracy and unbalance amount hardly effects to initial rotation accuracy. However, it shorten spindle's life because vibration and noise is increasing by increasing unbalance amount and we can expect situation that rotation accuracy is falling by long time operation.

• Journal of Chest Surgery
• /
• v.26 no.2
• /
• pp.108-114
• /
• 1993

The risks of homologous blood transfusion are well documented and recently increased with the emergence of acquired immunodeficiency syndrome. This is a report concerning 29 consecutive adult with no blood conservation patients (Group I) who had an elective cardiac operations. A similar group of 29 patients operated on 1992 but with blood conservation (Group II). In I of Group I patients and 15 of Group II patients, no homologous blood products were required. Group II patients used significantly less fresh frozen plasma (2.05${\pm}$0.68 unit versus 6.52${\pm}$0.72 unit, p<0.05) and the homologous blood transfusion (0.42${\pm}$0.9 unit versus 3.64${\pm}$0.17 unit, p<0.05) than Group I patients. Group II patients had also significantly less postoperative bleeding (338${\pm}$39.9 ml versus 585${\pm}$93.0 ml, p<0.05) than Group I patients. Group II patients recieved 460${\pm}$62.6 ml of mediastinal shed blood in acquired group. In conclusion, a simple and inexpensive blood conservation program, mainly combining autologous blood removal before bypass, retransfusion of the volume remaining in the oxygenator, and consistent autotransfusion of mediastinal shed blood has enabled us to avoid infusion of homologous blood in 15/29 patients of Group II patients. No side effects or complicatinos could be related to the blood conservation program.

• Journal of Mechanical Science and Technology
• /
• v.19 no.5
• /
• pp.1080-1086
• /
• 2005

The preliminary design optimization of multi-stage spur gear reduction units has been a subject of considerable interest, since many high-performance power transmission applications (e.g., automotive and aerospace) require high-performance gear reduction units. There are multiple objectives in the optimal design of multi-stage spur gear reduction unit, such as minimizing the volume and maximizing the surface fatigue life. It is reasonable to formulate the design of spur gear reduction unit as a multi-objective optimization problem, and find an appropriate approach to solve it. In this paper an interactive physical programming approach is developed to place physical programming into an interactive framework in a natural way. Class functions, which are used to represent the designer's preferences on design objectives, are fixed during the interactive physical programming procedure. After a Pareto solution is generated, a preference offset is added into the class function of each objective based on whether the designer would like to improve this objective or sacrifice the objective so as to improve other objectives. The preference offsets are adjusted during the interactive physical programming procedure, and an optimal solution that satisfies the designer's preferences is supposed to be obtained by the end of the procedure. An optimization problem of three-stage spur gear reduction unit is given to illustrate the effectiveness of the proposed approach.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.14 no.3
• /
• pp.594-602
• /
• 1990

A computer-aided design system of involute cylindrical gears(spur and helical gears) for power transmission is developed, in which the volume of a gear unit is minimized with satisfying various design constraints. As the design constraints, bending strength and pitting resistance of AGMA 218.01, scoring of Dudley's flash temperature, contact ratio, and involute interference of pinion are considered and effective factors for strength calculation(life, reliability, hardness ratio, load distribution, velocity, etc.) are also included. This complicated nonlinear optimization problem is solved by using ALM(Augmented-Lagrange-Multiplier) method with self scaling BFGS(Broydon-Fletcher-Goldfarb-Shanno) method employed for unconstrained optimization programming. This design method can be easily applied to designing power transmission gear unit in the machines of various kinds. It is expected for the proposed method to be a contribution for an automated design of gear unit towards weight minimization, miniaturization and high strength of gear unit.

• KIEAE Journal
• /
• v.10 no.5
• /
• pp.181-186
• /
• 2010

Research on construction waste unit was in progress in the 1995 when 'Proper Disposal and Recycling Measures for Construction Waste' was made by the Seoul Development Institute. Such an effort has been made in order to cope with the lack of natural resources in Korea and to utilize the reusable resources. Furthermore, these efforts have also increased due to the improved standing of Korea in the international community. A large number of residential buildings were built in the response to the government's policy by increasing the supply of houses between the 1970's and 1980's. In 2000, more reconstruction and redevelopment was done because of the aged buildings and change of use for those buildings. And the project has been actively promoted until now, which caused a sharp increase in the generation volume of construction waste. In Korea, 8 kinds of construction waste unit, including the standard construction manpower and materials estimation, are introduced. Currently, they provide standards to different building categories and waste properties while for construction sites different standards are applied. This study aims to measure the actual amount of construction waste after sample buildings are dismantled and analyzes the estimation of the waste quantity by using various standard units. Through comparison, this study will figure out the differences among the standard units in order to find out how to apply the standard units properly. Moreover, this research will provide practical measures to apply such units to construction sites.

• Journal of the Korean Society for Precision Engineering
• /
• v.25 no.5
• /
• pp.82-88
• /
• 2008

This paper proposes a novel method of 2 dimensional shape display. Shape displays allow us to feel tile actual volume of the object, unlike conventional 2D visual displays of 3D objects. The proposed method employs a wireframe structure to present 2D or 3D objects. The wireframe is composed of small units driven by shape memory alloy (SMA) actuators. The drive unit is analogous to the agonist-antagonist system of animal musculoskeletal systems, where the SMA actuators serve as agonist and antagonist muscles. The force in the SMA actuator is controlled by electrical current. The drive unit is equipped with the locking mechanism so that it can sustain the external force exerted by the user as well as the own weight of the wireframe structure. By controlling the current into the SMA actuator and locking mechanism, we can control the angle of the drive unit. A chain of drive units enables presentation of 2 dimensional objects. 3 dimensional presentations are possible by collecting the chains of drive units.

• The Korean Journal of Community Living Science
• /
• v.14 no.3
• /
• pp.89-98
• /
• 2003

To assess the actual status of businesses selling fermented soybean products, this study surveyed 130 Farmhouse style small size soybean sauce processing sites supported by the Rural Development Administration nationwide. The sex composition of the businesses representatives of 2% male and 98% female showed that a farmhouse soybean processing business is generally operated by rural women as a non-filming business. The percentage of co-worked sites was 71.2 and that of sites with permits was 39.2. The main products were meju, doenjang, and kanjang. Total production volume was found to be 523 tons, 256 tons, and 135 k$\ell$s, respectively. The number of years of experience of the manufacturers of the kanjang and doenjang was found to be 25.7 on average which shows that long-experienced, skilled manufacturers are participating in this project. The traditional measuring unit differed greatly depending on the region. This difference in the measuring unit of soybeans resulted in a large difference in the volume of doenjang and kanjang produced Per Province. For one kg of raw soybeans, the weight of Doenjang produced also varied from 2.14 kg in the Gyeongbuk area to 1.62 kg in Jeju. In the aspect of salt use, 1.75 $\ell$ (translated by volumetric unit 0.704 due) of salt pet kg of meju, in Jeju, was the highest in Korea. Government supervision would be beneficial in the areas of raw material products, standardization of measuring units and production methods, organization and operation of a conference for the different groups of producers, and in construction of a nationwide database.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.3
• /
• pp.20-28
• /
• 2007

The easiest way to see the phenomena of compressor surge is to show the static and dynamic operation characteristic on the map. Its operation zone will be restricted by the surge limit and, static and transient process must have some margin for it. Effect of rotor moment of inertia, air/gas volumes and heat transfer are factors to cause the transition from the static line. In case a large volume such as heat exchanger exists in the system it will exert a substantial influence to dynamic characteristics. In the present paper, influence of air volume bled from the compressor exit on transient process is investigated with an example of an auxiliary power unit micro-turbine engine. Turbine mass, pressure ratio, rotation speed, power and moment are calculated based on mass and work conservation. Result from the present study can give guidance to design the control system. A computer program is developed to calculate the dynamic process using the MathCAD commercial software.

• Korea Trade Review
• /
• v.42 no.2
• /
• pp.277-296
• /
• 2017

More than 95% of imports and exports in the World are being transported by vessels. In other words, marine transportation accounts for a large portion of share in the world trade. The purpose of this study is to analyze factors of seaborne trade volume according to items affecting on the world economy. This study conducted a linear regression analysis between seaborne trade volume and the world economy (world GDP) to estimate the correlation between them. Panel data analysis and random effects model analysis have been applied to examine the effect of seaborne trade volume. For this study, the seaborne trade volume is categorized into 10 items, and estimated how much global GDP will be affected when the trade volume changes. In addition, the granger causality test was conducted to verify the relationship between seaborne trade volume and the world GDP. As a result, seaborne trade volume and the world GDP were mutually influenced each other. However, seaborne trade volume affects the world economy more significantly. The items affecting world economic growth include petroleum products, crude oil, chemical products, and so on. The estimated value of the coefficients of petroleum products, crude oil and chemical products were 1.014, 1.013 and 1.010, respectively. The estimated value 1.014 of petroleum products means that the growth rate is 1.014 times higher than the current world GDP growth rate when the seaborne trade volume of petroleum products increased by one unit Lastly, this study examines the seaborne trade volume of 10 categories and then verifies whether the growth rate of world GDP will increase when the volume of seaborne trade increased. This study is expected to provide policy-makers with useful information about formulating policies related to international trade.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.6
• /
• pp.5-19
• /
• 2017

In this study, the effect of rock mass curtain grouting was investigated by analyzing the correlation between the parameters of the RMR & grout injection volume, Lugeon value & RQD, Lugeon value & cement injection volume. In order to investigate the effect of rock mass curtain grouting, we analyzed the grout injection volume of 315 curtain grouting holes at 9 tunnel face of NATM Subsea tunnels in gneiss area. The total grout injection volume in the Subsea tunnels study was slightly changed in some tunnels face but decreased with increasing the rating of parameters in spacing of discontinuity (R3, Js) and groundwater condition (R5). The geological anomalies of seismic survey (3D, TSP) and the inflow of probe hole were found to be more correlated of relative than the parameters of RMR. The unit injection volume was found to decrease with higher ratings in the parameters of the RMR except the weathering degree of the discontinuity (Jc, R4). The correlation between RQD and Lugeon values is not significant, but it can be confirmed that the Lugeon value tends to decrease as the RQD value increases.