• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.231-238
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• 2014

Optimum lot size calculation for real world manufacturing environment has been focused since last few decades. Several extensions have been made to the basic economic order and production order quantity models to realize the possible practical situations in industry. However, focus on work-in-process inventory has been ignored relatively. This paper provides a comprehensive review of the models developed for group technology based manufacturing environment focusing on work-in-process inventory. Models have been extended from a perfect manufacturing conditions to an imperfect manufacturing situation considering rework, rejection and inspection. Optimum lot size has been evaluated using a simple algebraic optimization approach. Significant parameters are highlighted using sensitivity analysis for the developed models. Numerical example is used to illustrate the utilization of such models in day-to-day production setups and the impact of significant factors' variation on total cost and optimum lot size.

• Structural Engineering and Mechanics
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• v.23 no.1
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• pp.29-42
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• 2006

This paper describes the design scheme of the three-dimensional structures based on the concept of the cellular automata simulation. The cellular automata simulation is performed according to the local rule. In this paper, the local rule is derived in the mathematical formulation from the optimization problem. The cell density is taken as the design variable. Two objective functions are defined for reducing the total weight of the structure and obtaining the fully stressed structure. The constraint condition is defined for defining the local rule. The penalty function is defined from the objective functions and the constraint condition. Minimization of the penalty function with respect to the design parameter leads to the local rule. The derived rule is applied to the design of the three-dimensional structure first. The final structure can be obtained successfully. However, the computational cost is expensive. So, in order to reduce the computational cost, the material parameters $c_1$ and $c_2$ and the value of the cell rejection criterion (CRC) are changed. The results show that the computational cost depends on the parameters and the CRC value.

• 전자공학회논문지 IE
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• v.45 no.4
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• pp.1-6
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• 2008

A fast-hopping frequency synthesizer that reduces complexity and power consumption is presented for MB-OFDM UWB applications. The proposed architecture uses 3960 MHz LC VCO, 528 MHz ring oscillator, passive mixer and LC-tuned Q-enhancement BPF to generate Band Group 1 frequencies. The adjacent channel rejection ratio is less than -40 dBc for 3432 MHz and -H dBc for 4488 MHz. A fast switching SCL-tpre MUX is used to produce the required channel output signal and it takes less than 2.2 ns for band switching. The total power consumption is 47.9 mW from a 1.8 V supply.

• Korean Journal of Child Studies
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• v.25 no.6
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• pp.15-34
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• 2004

This study is an attempt to develop the 'Parental Intelligence Scale', which can be applied in the parent education and counselling and provide more useful information for more appropriate interventions by evaluating the characteristics of parent's roles and strong/weak points of the parent's roles under the special situation and environments. In developing the scales, this study reviews of numbers of existing literatures, analysis of scales and tools on parent's role or attitude, collection of episodes on parent's role, validity check processes by field experts, and 2 rounds of factor analysis. The outcomes of the study are as follows; In regard of the development of Parental Intelligence Scale, 3 factors of care-giving role, management role, nurturing role were derived from the conceptual and measurement model. From these 3 factors, 8 sub-factors of empathy, encourage, enhancement, rational authoritativeness, flexibility, rejection, acceptance, control were constructed. 39 question items were derived in order to measure these sub-factors. Especially through the two rounds of factor analysis, the question items with enhanced internal consistency were derived and total cumulative variance was increased, which made theoretical model into the generalized model possible.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.3
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• pp.247-252
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• 2003

We propose an approximation of the M/G/1 system with finite workload capacity, where those customers whose admission to the system would increase the workload beyond a prespecified finite capacity limit are not accepted. Our approximation method is based on the idea that the service time of a customer in the M/G/1 system can be approximated as the sum of service times of a batch of customers in the $M^X/d/1$ system where the deterministic service time d is small enough. That is, the original service time is discretized and approximated by the batch size. We exemplified our method by obtaining the average workload of the M/M/1 system by means of the $M^X/d/1$ system, where the batch size is geometric. In addition, the approximate blocking probabilities of the M/M/1 and $M/E_k/1$ system with finite workload capacities are sought. The proposed method turns out to give a good approximation, which is compared with a simulation.

• Journal of Chest Surgery
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• v.25 no.5
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• pp.458-468
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• 1992

With the aid of extracorporeal circulation, nine dogs underwent orthotopic cardiopulmonary transplantation after preservation of the donor heart in a hypothermic amino acid[glutamate, aspartate] enriched high potassium extracellular solution, and preservation of the donor lung with hypothermic low potassium dextran solution from June 1990 to May 1991. The mean body weights of dogs were 20kg and the recipients` preoperative hematologic and hemodynamic pictures were within normal range except slightly decreased level of albumin and total protein, which was supposed to be due to malnutrition. The following modifications of the original Stanford technique were emphasized: [1] the posterior mediastinum is dissected as little as possible with meticulous hemostasis; [2] the surgical procedure is kept away from the phrenic and vagus nerves; [3] the tracheal anastomosis may be wrapped with recipient`s pulmonary artery flap or surrouding soft tissues. A combination of Cyclosporine, Azathioprine, corticosteroid was used as perioperative immunosuppressive therapy. Postoperatively all recipients could be weaned from extracorporeal circulation, showing favorable vital signs, but within 24 hours, irreversible congetive heart failure, ascites, arrhythmias developed with a mean survival time 13.6$\pm$6.6[n=9, range=6~26] hours. Hemoglobin and platelet counts were significantly[p<0.05] decreased postoperatively, which is thought to be attributed to blood damage by cardiopulmonary bypass and hemodilution. Postmortem finding included multiple subendocardial patch hemorrhage in both atrial and ventricular cavities, pulmonary and liver congestion, and all tracheal anastomoses were intact. Further consideration about quality control of the animal, infection, rejection, the effect of cardiopulmonary bypass on the experimental animal is required to improve the results.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.207-209
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• 2019

This paper proposes a grid-tied photovoltaic (PV) system, consisting of Voltage-fed dual-active-bridge (DAB) dc-dc converter with single phase inverter. The proposed converter allows a small dc-link capacitor, so that system reliability can be improved by replacing electrolytic capacitors with film capacitors. The double line frequency free maximum power point tracking (MPPT) is also realized in the proposed converter by using Ripple Correlation method. First of all, to eliminate the double line frequency ripple which influence the reduction of DC source capacitance, control is developed. Then, a designing of Current control in DQ frame is analyzed and to fulfill the international harmonics standards such as IEEE 519 and P1547, $3^{rd}$ harmonic in the grid is directly compensated by the feedforward terms generated by the PR controller with the grid current in stationary frame to achieve desire Total Harmonic Distortion (THD). 5-kW PV converter and inverter module with a small dc-link film capacitor was built in the laboratory with the proposed control and MPPT algorithm. Experimental results are given to validate the converter performance.

• Brain Tumor Research and Treatment
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• v.6 no.2
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• pp.78-81
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• 2018

Gliosarcoma (GS), known as variant of glioblastoma multiforme, is aggressive and very rare primary central nervous system malignant neoplasm. They are usually located in the supratentorial area with possible direct dural invasion or only reactive dural thickening. However, in this case, GS was located in lateral side of left posterior cranial fossa. A 78-year-old man was admitted to our hospital with 3 month history of continuous dizziness and gait disturbance without past medical history. A gadolinium-enhanced MRI demonstrated $5.6{\times}4.8{\times}3.2cm$ sized mass lesion in left posterior cranial fossa, heterogeneously enhanced. The patient underwent left retrosigmoid craniotomy with navigation system. The tumor was combined with 2 components, whitish firm mass and gray colored soft & suckable mass. On pathologic report, the final diagnosis was GS of WHO grade IV. In spite of successful gross total resection of tumor, we were no longer able to treat because of the patient's rejection of adjuvant treatment. The patient survived for nine months without receiving any special treatment from the hospital.

• Journal of Distribution Science
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• v.21 no.1
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• pp.33-43
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• 2023

Purpose: The present study demonstrates the netnography technique to explore and understand crowds' perceptions on the donation distribution by charitable crowdfunding platform official social media, Facebook. Research design, data and methodology: This paper conducts a netnography design to examine the perceptions of online communities on four prominent charitable crowdfunding platforms' Facebook. A total of 93 comments are studied by collecting and analyzing their comments thematically. Results: This study illustrates two main themes which are 'Recommended Review' and 'Non-Recommended Review'. 'Recommended Review' can be explained into six sub-themes which are 'Role of Religion', 'Encouragement to Donate', 'Platform Reliability', 'Volunteering Value', 'Platform Support', and 'Donation Convenience'. While 'Non-Recommended Review' reveals that 'Rejected Donation Amounts', 'Rejection of Advertisements', and 'Review by Authorities'. Conclusion: Online community comments play an important role in providing input to the experience of donating through charitable crowdfunding. The crowdfunding platform can make a benchmark for the services offered. The comments are needed to be given attention by maintaining the interaction between the platform and donors to recruit new donors and maintain existing donors. This study provides better understanding on online community perception towards charitable crowdfunding platforms. This study also contributes the discussion on charitable crowdfunding and online marketing literatures.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.496-498
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• 2021

In Korea, based on the high fertility rate before 1980, the total population has been steadily increasing, and since the mid-1980s, the fertility rate has fallen sharply and has fallen below the level of population replacement. The cause of low birth rate in the region is not voluntary rejection, but rather, it is necessary to find out the cause by identifying the structural causes of the local community from various angles. We collected local Internet news and local representative cafe data, where many mothers participate, based on the budget area with a very low fertility rate among various areas. Factors of childbirth inhibition were analyzed by using the frequency of concurrent words that became issues related to population decline, low birthrate, and child-rearing welfare.