• International Journal of Highway Engineering
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• v.15 no.5
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• pp.91-99
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• 2013

PURPOSES : This study aims at proposing the methodology for benefit evaluations in pavement maintenance methods and timings using KoPMS(Korean Pavement Management System) software which was developed for efficient pavement management. METHODS : This study classified pavement sections into 4 clusters considering AADT(Annual Average Daily Traffic) and ESAL(Equivalent Single-Axle Load) using cluster analysis and used the deterioration models in each cluster. Increased user costs due to pavement deterioration as time goes by and agent costs for maintenance were estimated. Based on deterioration model and KoPMS software, Methodology for benefit evaluation was proposed in pavement maintenance methods and with/without implementation using real pavement section data. RESULTS : This study verified that considering agent costs only would be constrained to decide pavement maintenance methods and timings, and ascertained that decision making with agent and user costs would be effective. In addition, this study revealed that pavement maintenance methods and timings can be affected by AADT and ESAL and frequent pavement maintenances can be more efficient for benefits in pavement sections with more AADT and ESAL. Also this study found that user costs would be more affected to decision making than agent costs. Moreover, Delay of conducting pavement maintenance caused increased vehicle operating costs and environmental costs because of poor conditions of pavements. CONCLUSIONS : This study proposed LCCA and benefit estimation methodology of pavement with considering agent and user costs. The results of this study can be used for baseline data of efficient pavement asset management.

• Atmosphere
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• v.31 no.4
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• pp.421-431
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• 2021

The Yeongdong region is frequently vulnerable to heavy snowfall in winter in terms of societal and economical damages. By virtue of a lot of previous efforts, snowfall forecast has been significantly improved, but the performance of light snowfall forecast is still poor since it is very conducive to synoptic and mesoscale interactions, largely attributable to Taeback mountains and East Sea effects. An intensive observation has been made in cooperation with Gangwon Regional Meteorological Office and National Institute of Meteorological Studies in winter seasons since 2019. Two distinctive Cold Air Damming (CAD) events (14 February 2019 and 6 February 2020) were observed for two years when the snowfall forecast was wrong specifically in its location and timing. For two CAD events, lower-level temperature below 2 km ranged to lowest limit in comparisons to those of the previous 6-years (2014~2019) rawinsonde soundings, along with the stronger inversion strength (> 2.0℃) and thicker inversion depth (> 700 m). Further, the northwesterly was predominant within the CAD layer, whereas the weak easterly wind was exhibited above the CAD layer. For the CAD events, strong cold air accumulation along the east side of Taeback Mountains appeared to prevent snow cloud and convergence zone from penetrating into the Yeongdong region. We need to investigate the influence of CAD on snowfall in the Yeongdong region using continuous intensive observation and modeling studies altogether. In addition, the effect of synoptic and mesoscale interactions on snowfall, such as nighttime drainage wind and land breeze, should be also examined.

• Korean Journal of Applied Biomechanics
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• v.31 no.4
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• pp.283-289
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• 2021

Objective: The aim of this study was to analyze the pattern of Kolman technique by five Korean top gymnasts including the three national athletes on horizontal bar. Method: Two digital high-speed camcorders were used with 90 frames/sec and their Kolman motions were filmed in sports science secondary school gymnasium at U city. After the kinematic and kinetic variables were carried out by Kwon3D 3.1 motion package during the whole phase, the optimized release motion was investigated by simulating the body COG path during the aerial phase. Results: Firstly, it was revealed that the average changes of hip, shoulder joint angle were 84 deg, 53 deg respectively during the functional sub-phase and the average swing phaseal time was 1.21 s. Secondly, it was revealed that the average body COG positions and velocities (Y, Z) at release were -0.65 m, 0.48 m, 1.65 m/s, 3.97 m/s respectively and the average release angle, peak height and flight time were 67 deg, 1.29 m, 0.79 s respectively. Thirdly, it was revealed that the directions of somersault of whole and lower body, tilt of lower body were counterclockwise, whereas the directions of tilt of whole body, twist of whole and lower body were clockwise at the ready for re-grasp. Lastly, it was revealed that the body COG paths were different from each other during the aerial phase followed by the different body COG velocities. Conclusion: Korean gymnasts of this study controlled their motions well in terms of the timing of hip·shoulder joint, body position, body angular momentum especially during the functional sub-phase, but their motions were different during the aerial phase. Nonetheless most of them made the adequate body position at the instant of re-grasp. It would be suggested that Korean gymnasts except S3 should increase the vertical velocity.

• Archives of Craniofacial Surgery
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• v.22 no.4
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• pp.177-182
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• 2021

Background: Although prompt surgery after an orbital fracture is preferable, the actual timing of surgery in real-world settings varies. Therefore, this study investigated the outcomes of implant surgery for inferior orbital wall fractures by comparing three groups according to the time interval between the injury and surgery. Methods: A retrospective review was conducted of patients' medical charts and initial computed tomography images from 2009 to 2020. The time to treatment was chosen by patients or their guardians based on the patients' comorbidities and the physician's explanation. The patients were divided into three groups according to the time of surgery (group 1: 3-7 days, group 2: 8-14 days, group 3: 15 or more days). Data were collected on age, the time interval until surgery, the dimensions of the defect, the operation time, the follow-up period, and the postoperative paresthesia score (ranging from 0 to 10). The outcomes were evaluated using a 4-point scale: 4=good (no complications), 3=fair (no subjective symptoms), 2=poor (remaining paresthesia), and 1=very poor (strabismus and/or enophthalmos). Results: The study included 85 patients with unilateral fractures who underwent surgery from 3 to 93 days after injury. The overall score distribution of the surgical outcomes was as follows: good=63, fair=7, poor=6, and very poor=9. The three groups showed no significant differences in the transverse dimension of the injury (p=0.110) or the anteroposterior dimension (p=0.144). In groups 1, 2, and 3, the postoperative outcome scores were 3.84±0.37, 3.63±0.87, and 2.93±1.33 (p=0.083), and the percentage of patients with good outcomes was 84%, 81.25%, and 57.14%, respectively. Conclusion: Performing surgery using an artificial implant within 2 weeks of the injury showed better outcomes and fewer postoperative complications than when treatment was delayed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.9
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• pp.1025-1031
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• 2019

This study proposes a PCS that enables efficient operation of seawater pumps for ships by implementing ML-based algorithms. Seawater temperature, RPM and power consumption data are acquired from two ships with PCS, analyzed with regression analysis method, and new algorithms are presented. Using the algorithms presented, Ship A saved about 36% compared to the PCS application, and ML-based algorithms in certain sea temperatures of 19 to 27 degrees Celsius and above 32 degrees Celsius were about 1% lower than Ship A's PCS. Ship B saved about 50% compared to PCS not applied, and about 2% more than Ship B's PCS in waters above $19^{\circ}C$, a specified sea temperature. The derived data can be used to suggest the optimum pump speed and sea route. In addition, the trend of acquired data can be used to infer the performance of the pump or the timing of elimination of the MGPS when efficiency becomes poor.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.309-315
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• 2018

In this paper, propose an efficient arc detection and control method to achieve fast machining speed, improved precision and surface roughness in discharge machining, especially for carbide and hard material processing and metal processing using discharge phenomenon as energy. A single discharge waveform is divided into three sections of Td (Time-Delay), Ton (Time-on) and Toff (Time-off) and the gate control timing is simulated using the HDL language. In this paper, we analyze the effect of the gap between the electrode and the workpiece on the machining results by determining the operation of the servo mechanism by sampling the Td section through the comparator circuit. As a result of the analysis, the Td section of the formed waveform was more precisely sampled at a high speed and the results were improved when applied to the gap control between the electrode and the workpiece.

• Journal of Korean Neurosurgical Society
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• v.62 no.6
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• pp.661-670
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• 2019

Objective : Rheumatoid arthritis (RA) is known to involve the cervical spine up to 86%. It often causes cervical instability like atlantoaxial subluxation (AAS), subaxial subluxation, and vertical subluxation (VS). In order to find the relation between RA and cord compression, we will evaluate the characteristics and risk factors of basilar invagination (BI) and cervicomedullary junction (CMJ) compression. Methods : From January 2007 to May 2015, 12667 patients administrated to Hanyang University Medical Center. Four thousand three hundred eighty-six patients took cervical X-ray and 250 patients took cervical computed tomography or magnetic resonance imaging. Radiologic parameters, medication records were obtained from 242 patients. Multivariate logistic regression analysis was performed with correlation of CMJ compression, basin-dental interval (BDI), basin-posterior axial line interval (BAI), pannus formation, BI, and AAS. Results : In the point of CMJ compression, atlantodental interval (ADI), posterior-atlantodental interval, BAI, AAS, and BI are relatively highly correlated. Patients with BI have 82 times strong possibility of radiologic confirmed CMJ compression, while AAS has 6-fold and pannus formation has the 3-fold possibility. Compared to the low incidence of BI, AAS and pannus formation have more proportion in CMJ compression. Furthermore, wrist joint erosion was correlated with VS and AAS. Conclusion : BI has a very strong possibility of CMJ compression, while AAS and pannus formation have a high proportion in CMJ compression. Hence bilateral wrist joint erosion can be used as an indicator for the timing of screening test for cervical involvement. We suggest the early recommendation of cervical spine examination for the diagnosis of cervical involvement in order to prevent morbidity and mortality.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.57-64
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• 2021

The domestic semiconductor industry can produce various products that will satisfy customer needs by diversifying assembly parts and increasing compatibility between them. It is necessary to improve the production line as a method to reduce the work-in-process inventory (WIP) in the assembly line, the idle time of the worker, and the idle time of the process. The improvement of the production line is to balance the capabilities of each process as a whole, and to determine the timing of product input or the order of the work process so that the time required between each process is balanced. The purpose of this study is to find the optimal WIP and buffer size through SA (Simulated Annealing) that minimizes lead time while matching the number of two parts in a parallel assembly line with bottleneck process. The WIP level and buffer size obtained by the SA algorithm were applied to the CONWIP and DBR systems, which are the existing production systems, and the simulation was performed by applying them to the new hybrid production system. Here, the Hybrid method is a combination of CONWIP and DBR methods, and it is a production system created by setting new rules. As a result of the Simulation, the result values were derived based on three criteria: lead time, production volume, and work-in-process inventory. Finally, the effect of the hybrid production method was verified through comparative analysis of the result values.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.73-87
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• 2011

An abnormal mono-specific bloom of the cyanobacterium Microcystis aeruginosa had developed at a specific location (transitional zone, monitoring station of Hoenam) in Daecheong Reservoir from middle of July to early August, 2001. The maximum cell counts during the peak bloom reached 1,477,500 cells/mL, which was more than 6~10 times greater than those at other monitoring sites. The hypothesis of this study is that the timing and location of the algal bloom was highly correlated with the local environmental niche that was controled by physical processes such as hydrodynamic mixing and pollutant transport in the reservoir. A three-dimensional, coupled hydrodynamic and ecological model, ELCOM-CAEDYM, was applied to the period of development and subsequent decline of the bloom. The model was calibrated against observed water temperature profiles and water quality variables for different locations, and applied to reproduce the algal bloom event and justify the limiting factor that controled the Microcystis bloom at R3. The simulation results supported the hypothesis that the phosphorus loading induced from a contaminated tributary during several runoff events are closely related to the rapid growth of Microcystis during the period of bloom. Also the physical environments of the reservoir such as a strong thermal stratification and weak wind velocity conditions provided competitive advantage to Microcystis given its light adaptation capability. The results show how the ELCOM-CAEDYM captures the complex interactions between the hydrodynamic and biogeochemical processes, and the local environmental niche that is preferable for cyanobacterial species growth.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.2
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• pp.129-138
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• 2021

Living modified organisms (LMOs) are managed by seven government agencies according to their use in South Korea. The Ministry of Environment is responsible for LMOs used for environmental remediation. This study aimed to develop guidelines for assessing potential risks posed by transgenic plants used for remediation to insect ecosystems by investigating arthropod communities in sunflower fields. A total of 2,350 insects and spiders belonging to 134 species of 10 orders and 71 families were collected from sunflower fields over four growth stages ranging from anthesis to seed maturity. At the R3 phase of flower-bud formation, Chironomidae sp. of a decomposer insect guild presented the highest density, while Apis mellifera of a pollinator guild was the most abundant in the R5.8 phase of flowering. During the R7 seed-filling phase and the R9 phase of seed maturity, herbivorous Pochazia shantungensis predominated. During the R9 phase, richness and diversity indices of arthropod communities were distinctly lower whereas their dominance indices were significantly higher than those at other phases. In addition, the composition of arthropod communities was strongly correlated not only with the sampling date, but also with the sampling method depending on the growth stage of sunflowers. Our results suggest that appropriate sampling timing and methods should be considered in advance and that long-term field trials that cover a variety of environmental conditions should be carried out to evaluate potential risks to insect ecosystems.