• Korean Chemical Engineering Research
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• v.56 no.1
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• pp.29-41
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• 2018

Separating a mixture having an azeotrope or low relative volatility with single distillation column is difficult. Separating water-acetic acid mixture and water-ethanol mixture with a distillation column consumes a lot of energy. Pervaporation membrane can be used to separate the mixture in the concentration region where separation is difficult with distillation. We simulated a distillation-membrane hybrid process where membrane is located on the head of the distillation column for efficient separation of water-acetic acid and water-ethanol mixture. Permeability data were obtained from experiments and literature. We formulated an optimization problem for the process with total annual cost (TAC) as an objective function and major design variables as optimization variables. Major optimization variable affecting TAC of the hybrid process was shown to be distillate concentration. We also suggested a simplified optimization procedure to get a close-to-optimal solution.

• Korean Journal of Psychosomatic Medicine
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• v.27 no.2
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• pp.101-110
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• 2019

Objectives : It is not clear which clinical variables are most closely associated with delirium in the Intensive Care Unit (ICU). By comparing clinical data of ICU delirium and non-delirium patients, we sought to identify variables that most effectively differentiate delirium from non-delirium. Methods : Medical records of 6,386 ICU patients were reviewed. Random Subset Feature Selection and Principal Component Analysis were utilized to select a set of clinical variables with the highest discriminatory capacity. Statistical analyses were employed to determine the separation capacity of two models-one using just the selected few clinical variables and the other using all clinical variables associated with delirium. Results : There was a significant difference between delirium and non-delirium individuals across 32 clinical variables. Richmond Agitation Sedation Scale (RASS), urinary catheterization, vascular catheterization, Hamilton Anxiety Rating Scale (HAM-A), Blood urea nitrogen, and Acute Physiology and Chronic Health Examination II most effectively differentiated delirium from non-delirium. Multivariable logistic regression analysis showed that, with the exception of vascular catheterization, these clinical variables were independent risk factors associated with delirium. Separation capacity of the logistic regression model using just 6 clinical variables was measured with Receiver Operating Characteristic curve, with Area Under the Curve (AUC) of 0.818. Same analyses were performed using all 32 clinical variables;the AUC was 0.881, denoting a very high separation capacity. Conclusions : The six aforementioned variables most effectively separate delirium from non-delirium. This highlights the importance of close monitoring of patients who received invasive medical procedures and were rated with very low RASS and HAM-A scores.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.1
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• pp.19-25
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• 2012

The air traffic situation variables were emphasized in this research to review the awareness level of job performance of military air traffic controllers in application of air traffic situation variables such as detection of aircraft identification, type of aircraft, position ,speed, altitude, determination of separation between departing and arriving in-trail aircraft, physical airport conditions, adverse weather conditions, NAVAID outage and ATC facilities' operational status. In this respect, This study was conducted under the auspice of ATC facility operating agencies and devoting air force air traffic controller's participation by answering the questionnaires from nine radar approach control facilities and other air traffic control towers.

• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.342-348
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• 2001

The present work is to introduce the preliminary experimental results for a primary hydrocyclones process in lake sediment thickening. A few cyclones based on the Rietema standard geometry were prepared. The test particles were sediments from a local lake and waste coal fly ash for a reference test. As a result of the chemical analysis, organic contaminants were abundantly found in smaller particles in overflow. Experimental results showed that the physical characteristics of particles, configuration of the cyclone and operating variables including feed solids concentration and volumetric flow rate could affect the separation efficiency. The limiting feeding velocity for the separation and enrichment of particles was 1.5 m/s, higher separation efficiency, in general, was obtained under the high velocity with the small cyclones.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.5
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• pp.879-893
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• 2016

This study explores the determinants of clothing disposition and examines their effect on the dimensions of clothing disposition behavior. The data of 316 women were collected nationwide using an online self-administered questionnaire. This study initially identified five types of disposition behavior as revising, permanent separation, giving away, selling, and donating to charity. Exploratory and confirmative factor analysis identified the underlying determinants of clothing disposition as self-concept, reusability, economic factor, social environment, affective association, storage, fashionableness, and a sense of belongingness. Structural equation modeling was conducted to examine the relationships between variables. The results demonstrated that six out of eight determinants significantly affected clothing disposition behavior. The effects of social environment and a sense of belongingness were relatively strong determinants that influenced the four types of disposition behaviors. However, self-concept and affective association did not influence the disposition behaviors. A series of one-way MANOVA was conducted to determine the effect of the eight demographic variables on the four modes of clothing disposition. Giving away, permanent separation, and donating to charity differed significantly in the groups of three demographic variables such as age, monthly income, and marital status. This study empirically elucidates what criteria consumers use when confronted with unused clothing and how the determinants of clothing disposition influence the modes of clothing disposition behavior. This study provides a framework for clothing disposition behavior and its determinants as well as suggests a new approach to clothing disposition behavior and improvements in marketing decisions.

• Resources Recycling
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• v.23 no.6
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• pp.30-39
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• 2014

The trajectories of PCB(Printed Circuit Board) particles in the corona discharge electrostatic separation was simulated. The PCB particles are prepared by crushing bare board, which disassembled from electronic components, consist mostly of copper and FR-4(Flame Retardant Level-4) Firstly, a model was established for calculating of detachment points of PCB particles from the rotating electrode in separator. The model of detachment points was derived from equilibrium of force such as gravity force, centrifugal force, electrostatic force. The trajectories of particles after detachment was calculated by acceleration derived from time-integrating method of motion equation. In this simulation, particle size, supplied voltage, rotation speed of rotating roll electrode and angle of induction electrode were adopted as variables. While the trajectories of FR-4 particles were affected by all variables, rotation speed of rotating roll electrode was dominant variables affecting trajectories of copper particles.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.4
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• pp.213-218
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• 2010

In this study, a star screen model was constructed to predict the dynamic characteristics of interactive waste particles and to simulate separation capability of the particle using geared type screen(star screen). In order to approach this model, it is necessary to determine the design parameters of the screen such as driving torque, percentage of open space, and capability. Thus, a dynamic star screen model was developed with a total of 32 columns of geared assembly including screen part, wastes guide, and extra joints to rotate the screen using ADAMS. Each parameter was simulated to predict the screening capability for particle size, rotating speed, and particle condition. From the results, separation ability was predicted according to the affecting variables by using the dynamic star screen model.

• 한국가스학회:학술대회논문집
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• 2005.10a
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• pp.141-145
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• 2005

DME (Di-Methyl Ether) is a new clean fuel and an environmental-friendly energy resource, also is recently increasing with an alternative interest because of the industrial use. DME has been shown to have excellent properties as a diesel fuel giving emission level better than ULEV standard. So it has been attracting considerable as an alternative diesel fuel. In this study, we carried out simulation of separation and purification process of demo plant for 101on per day DME production, which cause the effect that is important in productivity, from operation results of pilot plant for 50kg per day DME production. The liquefied stream, which was separated by gas-liquid separator after DME reactor, includes $CO_2$, DME, Methanol and $H_2O$. We established three distillation columns for separation and purification of the stream. $CO_2$ was extracted from the stream by first distillation column, DME was extracted by second column and Methanol was extracted by third column. We investigated and analyzed the effect which the actual operation variables cause in efficiency of process and optimized process, finally we got the DME of purity $100\%$.

• Resources Recycling
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• v.12 no.4
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• pp.44-50
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• 2003

Separation of mixed plastics is not a simple task due to similarities of specific gravity and limitations of sizes, etc. In this study, a new technique was developed to separate plastics selectively by a thermal adhesion method using the different softening or melting temperatures of various types of plastics. Tests were conducted to investigate softening or melting temperatures and adhesion probabilities of plastics with change in temperature. Tests also were conducted to analyze the operating variables, including contact times, size and color pigment. It was founded that LDPE, HDPE and PVC, PET, etc among mixed plastics could be separated selectively according to the change of temperature.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.5-12
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• 2015

This paper presents a numerical investigation of the effect of the dihedral stator on the loss in a transonic axial compressor. Four stator geometries with different stacking line variables are tested in the flow simulations over the whole operating range. It is found that a large shroud loss at the rotor outlet and the subsequent shroud corner separation in the stator passage occur at low mass flow rate. The hub dihedral stator and bowed blade generate unexpected hub-corner-separation, thereby causing a large total pressure loss over the entire operating range. However, the corresponding blockage forces the high momentum flow near the hub to divert toward the upper part of the passage suppressing the negative axial velocity region. The dihedral stator increases deflection angle and secondary vorticity near the endwall where the dihedral is applied. As a result, the endwall loss which is related to the endwall relative velocity decreases.