• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.33-39
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• 2004

The performance of a deep water drillship, is investigated with the view of the characteristics of the thrusters and the resistance increasement due to moonpooi. The model tests have been performed to obtain the resistance of two drillships with the moonpooi open and closed including shape changes of moonpool step. To design the DP system, thrust forces of azimuth thrusters have been measured during azimuthing at zero speed condition. Thrusters, azimuthing under the bottom of ship, have the interactions of the other thrusters due to flow changes made by other thrusters, and the existence of ship hull makes the thrust deduction higher than when the thrust operates by itself. The resistance increasement due to the moonpooi is highly dependent on the step height of the moonpool and the draft. It is found that the height of moonpool step can reduce the resistance increasement by moonpool.

• Journal of the Korea Furniture Society
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• v.25 no.3
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• pp.182-187
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• 2014

Underground shopping center has become a important commercial facility due to their good accessibility to the public transport. However, underground shopping center has high risk of air contaminants emission like formaldehyde and lowered indoor air quality. In this study, formaldehyde concentration of the underground shopping center was estimated according to the renovation and characteristics of space. It was found that newly renovated underground shopping center has low formaldehyde concentration. In case of closed entrance type, the formaldehyde concentration was 320 % higher than open type. Formaldehyde concentration was varied by product type and especially, high formaldehyde concentration was measured near the stores selling nail polish and cosmetics. It is important to apply appropriate ventilation system according to characteristics of space.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.39-51
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• 1987

This paper deals with the case analysis of second order processes under sampled-data. Proportional Integral-Derivative(PID) control, and development of Decision Support Systems(DSS) for such processes. In this paper three techniques were described for identifying the dynamics of closed loop stable processes. The first, called pulse testing is a frequency-domain method, which yields the frequency response diagram of an open loop process. The second is a time-domain method which yields the gain and time constants of the process model. The third technique is based on step response and gives the parameters of PID controllers. The development of DSS design programs consisting of above three techniques will provide very powerful tools in the microcomputer based process control.

• International Journal of Aeronautical and Space Sciences
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• v.12 no.1
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• pp.69-77
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• 2011

A peristaltic micropump with lightweight piezo-composite actuator (LIPCA) membrane valves is presented. The micropump contained three cylinder chambers that were connected by microchannels and two active membrane valves. A circular miniature LIPCA was developed and manufactured to be used as actuating diaphragms. The LIPCA diaphragm acted as an active membrane valve that alternate between open and closed positions at the inlet and outlet in order to produce high pumping pressure. In this LIPCA, a lead zirconium titanate ceramic with a thickness of 0.1 mm was used as an active layer. The results confirmed that the actuator produced a large out-of-plane deflection. During the design process, a coupled field analysis was conducted in order to predict the actuating behavior of the LIPCA diaphragm; the behavior of the actuator was investigated from both a theoretical and experimental perspective. The active membrane valve concept was introduced as a means for increasing pumping pressure, and microelectromechanical system techniques were used to fabricate the peristaltic micropump. The pumping performance was analyzed experimentally in terms of the flow rate, pumping pressure and power consumption.

• Journal of Korean Foot and Ankle Society
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• v.8 no.2
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• pp.182-190
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• 2004

Purpose: To evaluate the clinical feature and the results of the treatment of Lisfranc joint fracture/dislocation with limited open reduction, pin fixation and Ilizarov external fixation. Materials and Methods: From June 2001 to May 2003, six patients with Lisfranc fracture/dislocation were treated. The average periods of follow-up was 23 months. After limited open reduction on the second tarso-metatarsal joint, we performed pin fixation of the above joint. On the other Lisfranc joint fracture/dislocation, closed reduction and the application of Ilizarov external fixator was done. This rigid system produced the early partial weight bearing and joint motion of the injured foot and ankle joint. The parameters used were radiographic evaluation, patient's clinical assesment and the AOFAS midfoot score. Results: We used the Myerson's criterier to evaluate the radiographic result. All cases could be achieved more than nearly anatomical reduction. Three cases of excellent and 3 cases of good result could be obtained in the evaluation of the patient's clinical assesment. The average AOFAS midfoot score was 87.2 ($76{\sim}95$) points. Conclusion: The treatment using Ilizarov external fixation on Lisfranc joint fracture/dislocation can be another useful method.

• Journal of Korea Soil Environment Society
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• v.3 no.1
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• pp.31-44
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• 1998

The geochemical experiments were carried out to investigate a removal effect of heavy metals in abdndoned metallic mine wastes, and to conceive a treatment techniques of them. In order to prevent contamination, experiment appature was made of acrylic acid resin and polyethylene which resist to acid and alkali. Experiment models are devided into four groups based on the system environments, distribution patterns and a kind of filling materials. The first group is background model(model I ) which is filled with waste only and opened to air. The second one is four layer group which is subdivided into two models, opened and closed systems, and the third mix group which is subdivided into three models based on mixing ratio of filling materials and system environment like a layered group. The forth is composed of two layer model, lower one composed of waste and upper one limestone chips. Solution drained from Model Ishows a high contents of heavy metals on the all terms of experiments. Among the models, however, the closed mix model V and Ⅶ show the most effective removal of heavy metals liberated from wastes. Models having different mixing ratios of filling materials on closed systems does not affect in heavy metal removal effect. But, the distribution patterns of filling materials affect very much on removal effect of heavy metals. The closed models with same constitution ratios and distribution patterns of filling materials show more and less effective removal to the open models.

• Journal of the Korean Ceramic Society
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• v.53 no.1
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• pp.43-49
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• 2016

This analyzed a Young's modulus (E), a thermal expansion coefficient (TEC, ${\beta}$) and a thermal conductivity (${\kappa}$) of the material with simple cubic particulate inclusion using two model structures: a parallel structure and a series structure of laminated layers. The derived ${\beta}$ equations were applied to calculate the ${\beta}$ value of the W-MgO system. The accuracy was higher for the series model structure than for the parallel model structure. Young's moduli ($E_c$) of sintered porous alumina compacts were theoretically related to the development of neck growth of grain boundary between sintered two particles and expressed as a function of porosity. The series structure model with cubic pores explained well the increased tendency of $E_c$ with neck growth rather than the parallel structure model. The thermal conductivity of the three phase system of alumina-mullite-pore was calculated by a theoretical equation developed in this research group, and compared with the experimental results. The pores in the sintered composite were treated as one phase. The measured thermal conductivity of the composite with 0.5-25% porosity (open and closed pores) was in accordance with the theoretical prediction based on the parallel structure model.

• Korean Institute of Interior Design Journal
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• no.20
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• pp.91-97
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• 1999

Telecommuting becomes a new form of work according to the development of information technology. Therefore, the purpose of this study is to provide basic data for the interior space planning of telecommuting centers by means of surveying office workers' opinions. The major findings of this research are as follows. The opinion about whether to use telecommuting center if provided is showed highly positively. In the matter of space type of telecommuting center, 'mixing type I (open plan office but division with high partition)' is the most preferred, the next, is 'closed type'. The most preferred type of workstation is 'independent type', the next is 'X type' and the third is 'link type'. Preferred partition height is '1,300-1,500mm'. When planning telecommuting center, the most important element of space plan is 'size and layout of workstation' and the second is 'private space for confidential work'. In public workplace, the most important element 'refreshment space', and the second one is 'mailing system'.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.3
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• pp.1-10
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• 1996

In this paper, the problem of simultaneously allocating servers and loadings of stations in a class of manufacturing systems modelled as network of queues is considered. The throughput function of the closed network of queues is demonstrated as a Schur convex function of server allocation, that is, increasing the server allocation vector under majorization increases the performance in the ship in terms of the throughput. It also reduces the congestion in the open network of queues in terms of reducing the total number of jobs in the sense of likelihood ratio ordering. These are the extentions of the numerical results of Green and Guha (1995) in the service system with independent M/M/c systems to the network of queues. The results can be used to support production planning in certain manufacturing systems.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2399-2411
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• 1995

Crane operation for transporting heavy loads inherently causes swinging motion at the loads due to crane's acceleration or deceleration. This motion not only lowers the handling safety but also slows down the handling process. To complement such a problem, Korea Atomic Energy Research Institute(KAERI) has designed several anti-swing controllers using open loop and closed loop approaches. They are namely a pre-programmed feedback controller and a fuzzy controller. These controllers are implemented on a 1-ton crane system at KAERI and their control performances are compared. Test operations show that the new controllers are superior to that of conventional cranes in terms of robustness to the disturbances and adaptation capability to the change of rope length.