• IE interfaces
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• v.13 no.2
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• pp.195-203
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• 2000

This paper considers the problem of sequencing printed circuit boards(PCBs) on an automatic surface mount device(SMD) placement machine in order to minimize total setup time. Since the total set of component feeders needed by all boards cannot be loaded simultaneously on the magazine, the setup must be made between two successive boards in the sequence. It is assumed that the setup time depends on the number of component feeders to be replaced in the magazine. An important characteristic is that each feeder occupies a different number of slots in the magazine. This problem is equivalent to travelling salesman problem(TSP) except that the distances between two cities, that is, the setup times between two boards, are not known in advance. So, TSP-based heuristics with new distance functions are presented and their performances are compared through various test problems. Computational results indicate that our heuristics outperform existing methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1086-1094
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• 2020

AThis paper measured real sea area for performance analysis according to distance from west sea and south sea of Korea. The performance of the underwater OFDM system was analyzed by comparing the performance of the West and South Seas by adjusting the number of data repetitive transmissions and the pilot symbol placement interval parameters based on the real-sea data measured from the distance and Data rate of the West and South Sea vessels. In conclusion, when comparing the performance of the South Sea at the Data rate and distance, the BER performance of the South Sea was similar at the 5 km South Sea and 1 km West Sea under the same conditions. Placement interval of pilot symbol at 10 km of South Sea and 3 km of West Sea is (𝚫f, 𝚫t) = (6, 3) and the number of times the PRB is (R_f, R_t) = (2, 1) repeated. We confirmed that we can send high data over long distances in the South Sea.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.4
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• pp.403-409
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• 2017

In the case of an extraction in the maxillary anterior region, immediate placement of implant-supported fixed prosthesis can be considered as a treatment option. Fewer surgical operations, reduced treatment time, and optimal availability of existing bone are obvious advantages of the method; however, when applied in the continuous maxillary anterior region, inter-implant distance must be carefully considered, as well as accurate diagnosis and treatment planning for predictable outcome. In this case report, immediate placement of two implants in the continuous maxillary anterior along with bone graft following the extraction of root rests, and the restoration of provisional and implant-supported fixed prosthesis on a 63-year-old patient had resulted in both esthetically and functionally satisfactory clinical outcomes.

• Archives of Plastic Surgery
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• v.45 no.3
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• pp.222-228
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• 2018

Background The most common surgical treatment for paralytic lagophthalmos is the placement of a weight implant in the upper eyelid; however, this technique confers the risks of implant visibility, implant extrusion, and entropion. In this study, we present a new technique of placing platinum weight implants between the levator aponeurosis and inner septum to decrease such complications. Methods A total of 37 patients with paralytic lagophthalmos were treated between March 2014 and January 2017 with platinum weight placement (mean follow-up, 520.1 days). After dissecting through the orbicularis oculi muscle, the tarsal plate and levator aponeurosis were exposed. The platinum weights (1.0-1.4 g) were fixed to the upper margin of the tarsal plate and placed underneath the orbital septum. Results Five patients could partially close their eye after surgery. The average distance between the upper eyelid and the lower eyelid when the eyes were closed was 1.12 mm. The rest of the patients were able to close their eye completely. Three patients patient developed allergic conjunctivitis after platinum weight insertion, which was managed with medication. None of the patients complained of discomfort in the upper eyelid after surgery. Visibility or extrusion of the implant were observed in three patients. Conclusions Postseptal weight placement is a safe and reproducible method in both primary and secondary upper eyelid surgery for patients with paralytic lagophthalmos. It is a feasible method for preventing implant visibility, implant exposure, and entropion. Moreover, platinum is a better implant material than gold because of its smaller size and greater thinness.

• Journal of the Korean Society for information Management
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• v.34 no.1
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• pp.51-71
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• 2017

This study conducted a survey to measure recognition distance between the materials which are located separately in a children's library targeting 200 elementary school lower grade students, higher grade students, and school parents(adults). And compared recognition distance between the elements of materials of individual visitor group with multidimensional scaling and K-mean group analysis. Multidimensional Scaling (MDS) is a technique for projecting the cognitive state in space by evaluating the similarity or attribute of the analysis target. Even though it is mainly used for market diagnosis in marketing, It can also be applied to present an ideal physical layout plan by analyzing the distance. As a result of analysis, the main discoveries are as follows. First, elementary school students cognize child, baby and computer materials should be adjacent as a same group. But recognition of adults(school parents) is reflected by differing from elementary school students vastly. They cognize that computer materials should be formed as a special group separated from child and baby's materials. Second, elementary school higher graders and adults(school parents) groups also want to separate their main reading materials from baby's book, therefore They both want to secure silent reading space separating from baby. Third, as a result to confirming how this recognition distance system of materials is reflected in a real children's library through three children's libraries in Y-gu, Incheon, there is no library with structure according perfectly with a recognition system of a particular class, but a recognition system of adults and elementary school students is partially reflected because baby, child and computer materials, and baby and child materials are commonly separated and placed. It is difficult to insist that a recognition system of a visitor group, especially a recognition system of children is absolute consideration conditions in material placement of a children's library. However, understanding cognition of the user groups can be an important evidentiary factors to offer differentiated service space according to visitors and effective placement of the elements of library resources.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.24 no.66
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• pp.91-98
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• 2001

In this study, a heuristic for surface mounters is developed to find an efficient sequence on PCB and rack assignment by component grouping. As setting up 4 reels in a group, the distance of rack moving can be minimized. And then, a generalized model for N reels in a group is developed. It is found that the performance of this heuristic is better than other heuristics found in the literature. Throughout the simulation study, the suggested heuristic is performed about 8.2 ∼ 12% better than other heuristics.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.125-132
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• 1993

When a mobile robot moves around autonomously without man-made landmarks, it is essential to recognize the placement of surrounding objects especially for current position estimation, obstacle avoidance, or homing into the work station. In this paper, we propose a novel approach to recognize the floor paln for indoor mobile robot navigation using ultrasonic time-of-flight method. We model the floor plan as a collection of polygonal plane objects and recognize the floor plan by locating edges and vertices of the objects. The direction is estimated by the patterns of transmission beam and reception sensitivity of the ultrasonic transducer, and the distance is estimated by the correlation detection method. We show the validity of the proposed approach through experimental results and discuss the resolution and the accuracy of the estimation of direction and distance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.1 no.2
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• pp.182-189
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• 1989

The propose of this study is augmentation of heat transfer without additional external power in 2-dimensional impinging air jet. The passive heat transfer augmentation method tried in this experimental study is placement of rod bundles with the clearance, 2mm, in front of the heat transfer surface. The effects of pitch distance among rods and nozzle-to-target plate distance are investigated. The overall heat transfer rate of flat plate with rods reaches maximum at H/B=10 and P=40mm, and for H/B=2 and P=40mm the augmentation rate of heat transfer becomes maximum to a value which is about 1.57 times that of the flat plate without rods.

• The korean journal of orthodontics
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• v.48 no.4
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• pp.236-244
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• 2018

Objective: The aim of this study is to compare the adaptation of a straight wire between brackets positioned at the mid-lingual surface and those placed gingivally by using a three-dimensional simulation software. Methods: This cross-sectional study was performed using OrthoAid, an in-house software. The subjects were 36 adolescents with normal Class I occlusion. For each dental cast, two bracket positioning approaches, namely the middle and gingival, were examined. In the middle group, the reference points were placed on the mid-lingual surface of each tooth, while in the gingival group, the reference points were positioned lingually on the anterior teeth. A 4th degree polynomial was adopted, and the in-plane and off-plane root mean squares (RMSs) of the distances between the reference points and the fitted polynomial curve were calculated using the software. Statistical analysis was performed using the paired-samples t-test (${\alpha}=0.05$). Results: The mean in-plane RMS of the polynomial curve to the bracket distance in the gingival group was significantly lower than that in the middle group (p < 0.001). The off-plane RMS was higher in the gingivally positioned brackets in the maxilla than in the middle group (p < 0.001). However, the off-plane RMS in mandible was not statistically significantly different between the two groups (p = 0.274). Conclusions: The results demonstrated that the gingival placement of lingual brackets on the anterior teeth could decrease the distance between a tooth and the straight wire.

• Fire Science and Engineering
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• v.33 no.4
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• pp.89-96
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• 2019

In this study, alarm sound generated as a priority alert system propagation through an elevator shaft in apartment buildings were simulated using room acoustic simulation software. The simulations were conducted on three kinds of elevator hall plan with a different number of elevators and placement. First, the elevator shaft without sound absorption material was simulated as a condition of the present. When the distance from the alarm sound generating floor became farther, alarm sound level was decreased. However, the alarm sound level three-floor distance was about 54 dB(A)~56 dB(A) which were louder than a background sound level of typical apartment buildings. Sound absorption material placement proposed by previous studies were simulated and the alarm sound levels were decreased about 12 dB~16 dB. These levels were similar or lower than the background level of apartment buildings. From these results, it can be concluded that placing sound absorption material on the surface of the elevator shaft wall can be one of the methods to control the alarm sound as regulated in NFSC.