• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.4
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• pp.233-239
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• 2022

The injection molding process is a process in which thermoplastic resin is heated and made into a fluid state, injected under pressure into the cavity of a mold, and then cooled in the mold to produce a product identical to the shape of the cavity of the mold. It is a process that enables mass production and complex shapes, and various factors such as resin temperature, mold temperature, injection speed, and pressure affect product quality. In the data collected at the manufacturing site, there is a lot of data related to good products, but there is little data related to defective products, resulting in serious data imbalance. In order to efficiently solve this data imbalance, undersampling, oversampling, and composite sampling are usally applied. In this study, oversampling techniques such as random oversampling (ROS), minority class oversampling (SMOTE), ADASYN(Adaptive Synthetic Sampling), etc., which amplify data of the minority class by the majority class, and complex sampling using both undersampling and oversampling, are applied. For composite sampling, SMOTE+ENN and SMOTE+Tomek were used. Artificial neural network techniques is used to predict product quality. Especially, MLP and RNN are applied as artificial neural network techniques, and optimization of various parameters for MLP and RNN is required. In this study, we proposed an SA technique that optimizes the choice of the sampling method, the ratio of minority classes for sampling method, the batch size and the number of hidden layer units for parameters of MLP and RNN. The existing sampling methods and the proposed SA method were compared using accuracy, precision, recall, and F1 Score to prove the superiority of the proposed method.

• Journal of Microbiology and Biotechnology
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• v.11 no.3
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• pp.463-468
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• 2001

Cyclosophoraoses are a class of unbranced cyclic-(1longrightarrow2)-${\beta}$-D-glucans found in the Rhizobium species. Their unique cyclic structures and high solubility make them potent for inclusion complexation as a host for an insoluble guest molecule. A family of neutral cyclosophoraoses (DP 17-27) isolated from Rhizobium meliloti 2011 was used as a host for inclusion complexation with an insoluble guest drug, indomethacin. A high performance liquid chromatographic analysis indicated that the inclusion complexation of cyclosophoraoses greatly ehanced the solubility of indomethacin compared with ${\beta}$-cyclodextrin. The estimated value of the association constant of the complex in water for $\beta$-cyclodextrin and cyclosophoraoses was $523M^{-1} and 17,570M^{-1}$, respectively. NMR spectroscopy showed that the inclusion complex was characterized by the interaction of the indole ring moiety of indomethacin with the cavity of cyclosophoraoses.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.5
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• pp.454-458
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• 2010

Velopharyngeal insufficiency is defined as a status in which nasal cavity and oral cavity can not be sepa-rated when speaking, swallowing by any reason. It has been treated by palatorrhaphy, pharyn-geal flap, local flap, free flap etc. When the size of the defect is small, it can be restored by palatorrhaphy, pharyngeal flap etc. But they are not proper for treatment of the large size of defect. In that case, local flap and free flap are more beneficial. Although large defect can be restored by free flap technique, but it is very complex, time-consuming and may bring about esthetical, functional complications of donor site. Buccinator myomucosal flap is a kind of local flap and reported for the first time by Bozola et al in 1989 and it has become a useful way for reconstruction of large intraoral defect. Authors experienced the use of buccinators myomucosal flap for treating secondary velopharyngeal insufficiency with large soft palate defect and obtained good result. So we report the case with literature reviews.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.8
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• pp.671-675
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• 2014

Nozzle ring is an important part of turbocharger which is applied to today's most diesel engines. Turbo charger nozzle ring is difficult to process and takes a high cost and a long time relatively. For this reason, it is largely produced by using a precision casting. Investment method, the representative technology of precision casting, has excellent dimensional accuracy and can produce complex shapes relatively easily. However, it is difficult to avoid the casting defects such as shrinkage cavity and short shot. This study is to predict the casting defects which could be occurred during the investment method by use of finite element analysis software and to design the process and mold of the marine turbocharger nozzle ring.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.87.2-87.2
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• 2011

This paper describes internal flow of a fuel cell's blower, which is mainly used for detached house and apartment. Test blower is operated by a diaphragm, which has suction and discharge port on the top of the blower. For analyzing the internal flow of the blower, three-dimensional Navier-Stokes analysis is introduced in the present study. Hybrid grid system consisted of hexa hedral, tetra hedral and prism mesh is adopted to describe the complex geometry of the diaphragm blower. Throughout the numerical simulation, it is found that the present numerical modeling for analyzing the internal flow of the test blower is suitable for understanding the unsteady nature inside the cavity of the diaphragm. Detailed unsteady flow is analyzed using the results obtained by numerical simulation.

• Journal of the Korean Applied Science and Technology
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• v.22 no.1
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• pp.50-55
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• 2005

A comparison of alkali metal cation and alkaline earth cation solvent extraction was made for three additional monoionizable crown ethers and one diionizable crown ether. sym-(n-Octyldibenzo)-16-crown-5-oxyacetic acid $\underline{1}$ exhibited high efficiency and selecvity in solvent extraction of alkali metal cations with respect to that observed with alkaline earth cations. Sizes of $Na^+$ and $Ca^{2+}$ appropriately match with the cavity size of monoethyl sym-bis[4(5)-tert-butylbenzo]-16-crown-5-oxymethylphosphonic acid $\underline{3}$. As the result, $Na^+$ and $Ca^{2+}$ are the best extracted. sym-(n-Octyldibenzo)-16-crown-5-oxymethyldiphosphonic acid $\underline{4}$was found to be somewhat selective for $Na^+$ over $Li^+$ and other alkaline earth metal cations. In the complexation of alklaine earth cations by crown ether diphosphonic acid $\underline{4}$, $Ca^{2+}$ and $Sr^{2+}$ are the appropriate sizes, but lager $Ba^{2+}$ may be due to favorable formation of a sandwich type complex between the crown ether cavity and the dianion of the deprotonated crown ether phoaphonic acid moiety.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.803-810
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• 1992

With increases in the rotational speed of hydraulic machine, studies on the hydrodynamic characteristics of supercavitating cascade are important on the view of flow analysis and design of fluid machinery. In the present paper, the complex functions of nonlinear theory corresponding to the flow of supercavitating cascade can be obtained by distributing singulary singulary points such as sources, vortexes and doublets on hydrofoil and free streamline. The numerical calculations on the closed wake model and semi-closed wake model are carried out in order to show the flow characteristics around the supecavitating cascade with finite with finite cavity length. As the result of this study, the flow characteristics such as lift, drag and cavitation coefficients are predicted by the flow conditions of supercavitating cascade in the fluid machinery.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1995.03a
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• pp.196-202
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• 1995

Drawbead formulation is the first process together with a binder wrap process in a sheet metal forming process. The purpose of a drawbead is to control the flow of the metal into the die in panel press forming. To simulate the drawbead formation process, an elasto-plastic finite element formulation is derived from the equilibrium equation an drelated boundary conditions considering the proper contact conditons. The developed finite element program is applied to drawbead formation in the plane strain condition. The simulation of drawbead formation produces the distribution fo stress and strain along the bead and the resultant elongation of the sheet in the cavity region with respect to various cavity dimensions of the sheet as well as the punch force of a drawbead and the amount of draw-in with respect to the stroke fo a drawbead. The numerical resutls provides the fundamental information as a boundary condition to analyze the complex binder wrap phenomena and panel press forming in simple way.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.4 no.1
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• pp.24-32
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• 1991

Cleft palate or velopharyngeal incompetence shows many disorders and disabilities affecting speech transmission. including distortion. substitution. and the nasalization of the vowels. The nasalized vowels are produced primarily by lowering of the velum. resulting in opening a side passage for the air flow through the nasal cavity. These abnormal movements give rise to complex modification of the physical property of the sound or in the sound spectrum. The authors employed Sonagraph$^{\circledR}$ as a sound analyzer in order to ascertain the features which characterize the nasalization of vowels. Twenty healthy Korean male adult voluteers were analyzed in artificial conditions of anterior and posterior nasal obstruction. and velo-pharyngeal incompetence. The results were as follows : 1) Fundamental frequency was not changed by nasal obstruction or velopharyngeal incompetence. 2) There was no significant difference of the formant intensity between normal and nasal vowels. 3) In VPI, a decrease of the frequency of $F_2$ was observed in /e/ and /i/ vowels(p<0.001). 4) In VPI, the $F_2$ was frequently missed in /o/ and /u/ vowels. 5) In the consonant spectra of VPI, the 'release burst' was usually not observed.

• The KSFM Journal of Fluid Machinery
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• v.7 no.1 s.22
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• pp.51-57
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• 2004

The waterhammer has recently become more important because the pumping stations were big and the systems conveying the fluid through the large and long transmission pipelines were complex. When the pumps are started or stopped for the operation or tripped due to the power failure, the hydraulic transients occur as a result of the sudden change in velocity As the pressure waves are propagating between the pumping station and the distributing reservoir, the pressure inside the pipe drops to the liquid vapor pressure with the pipeline profile, at which time a vapor cavity forms, and finally the column separation occurs. If the pressure in the pipe is less than the atmospheric pressure, the pipe can be collapsed and destroyed after the water columns separated by the vapor cavity rejoin. During the reverse flow, the pressure is so abnormally increased at the pumping station that the accident of flooding may happen due to the failure of system. In this paper, the field tests on the waterhammer by the startup, stoppage, and power failure of a centrifugal pump were carried out for Yongma transmission pumping station in Seoul. The experimental results were compared with that of the numerical calculations, in which results the procedure of controlled pump normal shut-down and the two-step closing mode of controlling the ball valve for pump emergency stop are proposed to reduce the pressure surge.