• East Asian mathematical journal
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• v.19 no.1
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• pp.81-89
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• 2003

There are many algorithms for factoring integers. The trial division algorithm is one of the most efficient algorithms for factoring small integers(say less than 10,000,000,000). For a number n to be factored, the runtime of the trial division algorithm depends mainly on the size of a nontrivial factor of n. In this paper, we create a function named factors that can implement the trial division algorithm in ActionScript and using the factors function we construct an interactive Prime Factorization Movie and an interactive GCD Movie.

• Journal of Acupuncture Research
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• v.26 no.5
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• pp.105-116
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• 2009

The use of acupuncutre has been increased worldwide, and large number of researches on acupuncture with improved quality has been conducted. Nevertheless, results of acupuncture treatment in those research tend to show mixed results, while many patients continuously seek acupuncture treatment as an adjuvant or alternatives for their health. Researchers and clinicians relevant to acupuncture are faced at this problematic discrepancy between the results of acupuncture in clinical trial including an randomized controlled trial and those of day-to-day clinical practice. The methodology of pragmatic clinical trial seems to be one of the promising research tools administering this problem especially in the area of complementary alternative medicine and traditional Korean medicine. In this study we first reviewed articles on the pragmatic clinical trial, summarized the essential concepts of 'explanatory' clinical trial 'pragmatic' clinical trial and then presented recent recommendations and arguments on this issue. We also analyzed and compared two similar pragmatic clinical trial protocols to show the readers the complexity of research designing. We hope more researchers in traditional Korean medicine will be interested in the methodology of pragmatic clinical trials and this study will serve to produce various high-quality clinical trials.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.101-107
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• 2007

In this paper, we have presented the results of Wavelength Division Multiplexing-Passive Optical Network (WDM-PON) based fiber-to-the-home (FTTH) field trial test which was held in the city of Gwangju. We have implemented an injection locked Fabry-Perot Laser Diode (FP-LD) based WDM-PON system and reliably delivered Internet Protocol TV (IP-TV), networked Personal Video Recorder (N-PVR), High-Definition Video on Demand (HD-VoD), Education on Demand (EoD) and Internet service as FTTH service through the system during the field trial test. We have also verified that the WDM-PON system worked well to provide quality of service (QoS) guaranteed 100Mbps bandwidth per subscriber. Furthermore, we have presented network designing issues in Outside Plant (OSP) and Customer Premises Network (CPN) that should be overcome to efficiently deploy FTTH service. Finally, based on the field trial test results, we proposed FTTH service deployment strategies.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.178-188
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• 2019

When burying underwater cables using robots, heading control is one of the key functions for the robots to improve task efficiency. This paper addresses the heading control issue for URI-T, an ROV for underwater construction tasks, including the burial and maintenance of cables or small diameter pipelines. Through modeling and identifying the heading motion of URI-T, the dynamic characteristics and input limitation are analyzed. Based on the identification results, a PD type controller with appropriate input treatment is designed for the heading control of URI-T. The performance of the heading controller was verified in water tank experiments. The field applicability of the proposed controller was also evaluated through the sea trial of URI-T at the East Sea, with a water depth of 500 m.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.3
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• pp.318-325
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• 2015

Korea has very strong shipbuilding industry in the world, so many new ships are constructed in Korean shipyards. These built vessels are carrying out sea trial at sea before delivering to shipowner, and sea trial ships cause navigation risk to other passing vessels to accomplish sea trial tests as quick turning, zigzag maneuvering and crash astern etc. in traffic congestion conditions. It occurred more than 1 collision accident related sea trial for recent 5 years. It has been increased about 30% of risk because of navigation of sea trial vessel by marine traffic flow simulation. This paper analyzed marine traffic density surveyed by AIS data for 7 days, and investigated position of marine accidents for 5 years in Korean coastal waterway, it established the sea trial prohibition areas as 10/100 level of total marine traffic volume, which is considered no danger for ship operator. This analyzed maritime safety law for setting of the prohibition waters to propose the basic legal system. It makes contribution to marine pollution prevention by setting of the sea trial prohibition water to improve the ship's navigation safety.

• Tuberculosis and Respiratory Diseases
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• v.84 no.4
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• pp.291-298
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• 2021

Background: Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is a standard diagnostic method for mediastinal and hilar lymphadenopathy. Although rare, fatal infectious complications can occur following EBUS-TBNA. However, to date, there is a lack of effective preventive strategies to reduce these complications. We started a trial to investigate the effect of chlorhexidine mouthrinse on the prevention of microbial contamination during EBUS-TBNA. Methods: This study is a single-center, parallel-group, assessor-blinded randomized controlled trial (RCT). We will enroll 112 adult participants undergoing EBUS-TBNA using a convex probe, and randomly assign them to two groups at a 1:1 ratio. The intervention group will gargle for 1 minute with 100 mL of 0.12% chlorhexidine gluconate before EBUS-TBNA, while the control group will have no mouthrinse before the procedure. Immediately after completion of EBUS-TBNA on all targeted lesions with an aspiration needle, a needle wash sample will be taken by instilling 5 mL of sterile saline into the used needle. The primary outcome is colony forming unit (CFU) counts in aerobic cultures of the needle wash samples. Secondary outcomes are CFU counts in anaerobic cultures, fever within 24 hours after EBUS-TBNA, and infectious complications within 4 weeks after EBUS-TBNA. Conclusion: This trial was designed as the first RCT to investigate the effect of chlorhexidine mouthrinse on the prevention of microbial contamination during EBUS-TBNA. Results from this trial can provide clinical evidence for a simple, safe, and cost-effective strategy to prevent infectious complications following EBUS-TBNA (ClinicalTrials.gov ID: NCT04718922, registered on 22 January 2021).

• Journal of the Korean Data and Information Science Society
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• v.13 no.1
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• pp.25-34
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• 2002

In this paper, we proposed multiple trial unrelated question models that more efficient by reducing the variance of the estimate than single trial unrelated question models investigated by Greenberg et al.'s (1969) and Kim et al.'s (1992) an d Lee & Hong's (1998).

• Journal of Gastric Cancer
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• v.17 no.3
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• pp.255-266
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• 2017

Purpose: Although Roux-en-Y (R-Y) reconstruction after distal gastrectomy has several advantages, such as prevention of bile reflux into the remnant stomach, it is rarely used because of the technical difficulty. This prospective randomized clinical trial aimed to show the efficacy of a novel method of R-Y reconstruction involving the use of 2 circular staplers by comparing this novel method to Billroth-I (B-I) reconstruction. Materials and Methods: A total of 118 patients were randomly allocated into the R-Y (59 patients) and B-I reconstruction (59 patients) groups. R-Y anastomosis was performed using two circular staplers and no hand sewing. The primary end-point of this clinical trial was the reflux of bile into the remnant stomach evaluated using endoscopic and histological findings at 6 months after surgery. Results: No significant differences in clinicopathological findings were observed between the 2 groups. Although anastomosis time was significantly longer for the patients of the R-Y group (P<0.001), no difference was detected between the 2 groups in terms of the total surgery duration (P=0.112). Endoscopic findings showed a significant reduction of bile reflux in the remnant stomach in the R-Y group (P<0.001), and the histological findings showed that reflux gastritis was more significant in the B-I group than in the R-Y group (P=0.026). Conclusions: The results of this randomized controlled clinical trial showed that compared with B-I reconstruction, R-Y reconstruction using circular staplers is a safe and feasible procedure. This clinical trial study was registered at www.ClinicalTrials.gov (registration No. NCT01142271).

• Journal of Communications and Networks
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• v.4 no.4
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• pp.363-369
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• 2002

Towards the deployment of 3rd generation systems, Virtual Home Environment (VHE), stemming from 3GPP, appears to be a powerful concept advocating the provision and delivery of personalized services to roaming users across network and terminal boundaries. This paper aims to expose the pathway for materializing the VHE concept, via the specification, implementation and evaluation of a prototype. Core aspects for realizing the concept such as the business and roaming models are presented, while a VHE enabling architecture utilizing key technologies (OSA/Parlay, MExE, and USAT) is introduced. The proposed architecture has already been evaluated by performing an initial trial demonstration. Currently it is being extended to support VHE service provision to roaming users, an aspect to be addressed by the final trial.

• Journal of Communications and Networks
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• v.16 no.5
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• pp.523-533
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• 2014

Orthogonal frequency division multiple access (OFDMA) is a promising technique, which can provide high downlink capacity for the future wireless systems. The total capacity of OFDMA can be maximized by adaptively assigning subchannels to the user with the best gain for that subchannel, with power subsequently distributed by water-filling. In this paper, we propose the use of composite differential evolution (CoDE) algorithm to allocate the subchannels. The CoDE algorithm is population-based where a set of potential solutions evolves to approach a near-optimal solution for the problem under study. CoDE uses three trial vector generation strategies and three control parameter settings. It randomly combines them to generate trial vectors. In CoDE, three trial vectors are generated for each target vector unlike other differential evolution (DE) techniques where only a single trial vector is generated. Then the best one enters the next generation if it is better than its target vector. It is shown that the proposed method obtains higher sum capacities as compared to that obtained by previous works, with comparable computational complexity.