• Restorative Dentistry and Endodontics
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• v.42 no.4
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• pp.316-323
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• 2017

Objectives: This study compared the amount of apically extruded bacteria during the glide-path preparation by using multi-file and single-file glide-path establishing nickel-titanium (NiTi) rotary systems. Materials and Methods: Sixty mandibular first molar teeth were used to prepare the test apparatus. They were decoronated, blocked into glass vials, sterilized in ethylene oxide gas, infected with a pure culture of Enterococcus faecalis, randomly assigned to 5 experimental groups, and then prepared using manual stainless-steel files (group KF) and glide-path establishing NiTi rotary files (group PF with PathFiles, group GF with G-Files, group PG with ProGlider, and group OG with One G). At the end of canal preparation, 0.01 mL NaCl solution was taken from the experimental vials. The suspension was plated on brain heart infusion agar and colonies of bacteria were counted, and the results were given as number of colony-forming units (CFU). Results: The manual instrumentation technique tested in group KF extruded the highest number of bacteria compared to the other 4 groups (p < 0.05). The 4 groups using rotary glide-path establishing instruments extruded similar amounts of bacteria. Conclusions: All glide-path establishment instrument systems tested caused a measurable apical extrusion of bacteria. The manual glide-path preparation showed the highest number of bacteria extruded compared to the other NiTi glide-path establishing instruments.

• Korean Journal of Weed Science
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• v.11 no.1
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• pp.60-67
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• 1991

The experiment was conducted to evaluate weeding effect and to inhibit tuberization of Eleocharis kuroguwai authority by single or systematic applications of several herbicides. E. kuroguwai was controlled above 90 percentage by pretilachlor and butachlor+bensulfuron application at 5-10 DAT(Days after transplanting) followed by bentazon at 50 DAT and weeded 88 percentage by mefenacet+bensulfuron application at 15 DAT. Tuberization inhibition rate of E. kuroguwai was higher at the application of butachlor+bensulfuron at 5 DAT followed by bentazon at 50 DAT than any other applications. The weight variation of E. kuroguwai tubers formed at 15-20cm soil stratum was larger than that at 10-15cm. Tuber of E. kuroguwai was hardly formed at top soil stratum (0-5cm) and deep soil (15-20cm) by the systematic application of bentazon at 50 DAT. Grain yield of rice from systematic application with bentazon at 50 DAT and mefenacet+bensulfuron at 10-15 DAT was similar to that of hand weeded plot.

• Journal of Korea Water Resources Association
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• v.40 no.9
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• pp.735-742
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• 2007

In this study, a methodology which is based on segments and minimum outsets to estimate the reliability of a real water distribution system efficiently and accurately is suggested. The current reliability assessment models based on minimum cutset consider a pipe as only area impacted by a pipe failure which incurs underestimation of pipe failure impact. In contrary, the suggested methodology adopts "segment" and "unintended isolation" with the hydraulic pressure failure area to define the actual service interruption area in a water distribution system due to a pipe failure, which is different from the Previous reliability estimating methodologies. In addition, a minimum cutset is defined as a single segment incurring abnormal operating conditions and the success mode approach is used to account for the probability of multiple failure combinations of minimum outsets. The model considers numbers and locations of on-off valves when the service interruption area is defined. Once the methodology is applied to a real water distribution system, it is possible to define actual service interruption areas and using the defined areas, the reliability of the water distribution system is estimated reliably, compared with the previous reliability assessment methodologies.

• Journal of Animal Science and Technology
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• v.54 no.5
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• pp.375-379
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• 2012

This study was carried out to define the "Wolla" coat color using 376 Jeju registered horses (white patched 142, solid coat color 234). Three major factors related to the white patches i.e ECA3-inversion for Tobiano, EDNRB 2 bp nucleotide substitution for frame Overo, and the KIT intron 16 single nucleotide polymorphism (SNP) for Sabino types of coat color were analyzed. It was found that out of 142 Jeju horses with white patches that have the genotype for ECA3-inversion (To) 140 horses were +/To heterozygous and 2 horses were To/To homozygous all Jeju horses with white patches had ECA3-inversion allele. However, there was no frame Overo or Sabino allele type in EDNRB and KIT intron 16 SNP in Jeju horses with white patches. As for 234 Jeju horses with a solid coat color, there was no ECA3-inversion allele related to the white patches. Thus, it could be considered that Wolla coat color with white patches in Jeju horses might have come from the Tobiano line in the genetic classification by coat color.

• Journal of Advanced Navigation Technology
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• v.3 no.2
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• pp.108-119
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• 1999

In recent, there has been remarkable progress in the field of GPS applications. In a few years, an appreciable number of aircraft will adopt GPS as a landing guidance system because GPS is more economic, more reliable and more accurate than any other aviation systems. In this respect, we have performed several helicopter landing flight tests based on the real-time DGPS system made in SNUGL (Seoul National University GPS Laboratory). From the experimental results, we found several problems Which should be fixed to adopt DGPS as a aircraft landing guidance system. In this paper, we will introduce the problems found in tests and also suggest modifications to solve the problems. Our modifications can be classified into three parts. The first is about the attitude determination with single GPS antenna. The second deals with the cockpit display module. The display was devised to integrate the Instrument Landing System(ILS) with tunnel-the-sky using virtual reality. With the display, pilot can achieve more safe landings. The last part is the digital map. We inserted digital map into our system and put direction indicator on the map using position information from GPS. It is very useful for pilot to find airports even in bad weather. Using the newly designed DGPS landing system, we conducted flight test at Kimhae International Airport, Pusan, Korea. It was successful! Our system can also satisfy Category-I criterion for aircraft landing approach and determine attitude angle with a high level of reliability. It is supported by video materials.

• Journal of Arbitration Studies
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• v.15 no.1
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• pp.3-26
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• 2005

Since the Agreement on Commercial Arbitration was signed by the Governments of South and North Korea last year, there has been quite a few discussions on the way for implementing the Agreement in both public and private sectors. The Department of Justice of South Korea was quite active in making the draft of arbitration rules representing the South Korean views in alliance with the Department of Reunification of South Korea and recently held an informal seminar to preview their draft. On the other hand, the Korea Arbitration Association, a main body of commercial arbitration which are composed of professors and lawyers, were carefully watching the steps and the draft made by the Department of Justice. The reasons are to assure that not only shall the commercial arbitration rules comply with comment norms of international arbitration but shall it be made to meet the needs of enterprises investing in the Special Economic District of Kaesung City in North Korea. The concerns of the Korea Arbitration Association can be accomplished if the Department of Justice would modify the provisions pointed out in the seminars. Five general principles shall be brought into the attention in promulgating the commercial arbitration rules. First, it should comply with the Agreement on Commercial Arbitration signed by South and North Korea. Second, it should accept common rules contained in UNCITRAL arbitration rules. Third, it should boost the promptness of proceedings when a case was filed. Fourth, it should feature unique aspects of trade between South Korea and Korea by differentiating it from purely international trade between a country and a country. Lastly, it should combine the respective rules of both South and North Korea, currently in effect. With the above five principles accomplished, it should be noted that the Agreement on Commercial Arbitration the upper authority of arbitration rules, mandates the following features. It declared that arbitration be processed by three arbitrators. Single arbitrator is not permitted. Arbitration can be adopted even if an arbitration clause does not exist in an agreement by the parties, provided that the dispute arose out of the scope of the Agreement on investment Guarantee signed by South Korea and North Korea. It excluded quick and simplified procedures even if the amount of claim in arbitration is minimal. All the procedures should take a formal procedure. It let the double administration offices operate. One is to sit in Seoul of South Korea and the other is to sit in Pyongyang of North Korea. This would intimidate the fastness of procedures. With the above principles and the features considered, each provision in the draft by the Department of Justice should be reviewed and suggested for change.

• International Journal of Railway
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• v.1 no.4
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• pp.149-156
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• 2008

During maintenance or construction works in or at the tracks of railways, high risks for passengers and railway staff, especially for the workers on the construction site exist. The high risks result out of the movement of rail vehicles, like trains or construction vehicles, which must be faced by using any available technical and operational technologies for securing them against the environment. Therefore, it is necessary to evaluate the level of protection continuously and to identify new and innovative methods and technologies for the protection of the gang (construction worker, machines and material). Especially on construction sites at line sections with two or more parallel tracks but also with single tracks, there are still a lot of incidents and accidents mostly with seriously injured persons or fatalities. These were mainly gang members that breach the railway-loading gage. By using proper warning or protection systems, the avoidance of such accidents must be achieved. The latest developments. in gang protection systems concern on the one hand fixed barriers in the middle between the construction site and the operated track and on the other hand construction vehicles equipped with automatic warning systems. The disadvantage of such protection methods is that the gang can be warned against an approaching train but a monitoring of the gang members cannot be performed. Only one part of a potential dangerous situation will be detected. If the gang members will overhear the acoustic warning signal of the security staff and the workers will not leave the danger zone in the track, the driver of the approaching train had no chance to react to the dangerous situation. An accident is often inevitable. While the detection of acoustic warning signals by the gang members working on a construction site is very difficult, the acoustical planning of an automatic warning system has to be designed for an acoustic short range level of one meter besides the construction vehicle. The decision about the use of today's technical warning system (fixed systems, automatic warning systems, etc.) must be geared to the technical feasibility and the level of safety which is needed. Criteria for decision guidance to block a track should be developed by danger estimation and economical variables. To realize the actual jurisdiction and to minimize the hazards of railway operations by the use of construction vehicles near the tracks further developments are needed. This means, that the warning systems have to be enhanced to systems for protection, which monitor the realization of the warning signal as a precondition for giving a movement authority to a train. This method can protect against accidents caused by predictable wrongdoing. The actual state of the art technique of using a collective warning combined with additional security staff is no longer acceptable. Therefore, the Institute of Transportation System of the German Aerospace Center in Braunschweig (Germany) will develop a gang warning and protection system based upon imaging methods, with optical sensors such as video in visible and invisible ranges, radar, laser, and other. The advantage of such a system based on the possibility to monitor both the gang itself and the railway-loading gauge either of the parallel track or of the same track still in use. By monitoring both situations, the system will be able to generate a warning message for the approaching train, that there are obstacles in the track, so that the train can be stopped to prevent an accident. And also the gang workers will be warned, while they breach their area.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.779-787
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• 2018

As security problems of the paper ballot have been emerged on and on, electronic voting with enhanced security and convenience has been introduced in several countries. However, it has not been adopted most of countries because of the problems that come from interdependence and security flaws. Meanwhile, the blockchain technology has high reliability due to the mechanism of mining that miners verify and preserve blocks independently by using P2P formation which does not have a central authority. Furthermore, because each block refers to the hash of the previous block. if any one block is changed, it is very difficult to forge and modify the blockchain because all blocks must be changed. If this technology is applied to the E-voting, integrity, and transparency about the result of the ballot is guaranteed. In this paper, we propose and implement an electronic voting system based on blockchain that improves interdependence, the reliability of excessive TTP and single point of failure come from original electronic voting. Also, we analyze the security and advantage of the proposal system compared with the existing bitcoin-based electronic voting system.

• Journal of Korean Society of Transportation
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• v.22 no.6
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• pp.35-47
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• 2004

Using data envelopment analysis, this paper annually estimates Malmquist total factor productivity indices and decomposes them into productive efficiency change, technical change, and scale change components for three publicly-owned rail transit properties: the Seoul Subway Corporation(SSC), the Seoul Metropolitan Electrified Railways Sector of Korea National Railroad (SMESRS) and the Busan Urban Transit Authority (BUTA). The paper then conceptualizes that the property produces a single output(car-kilometers) using four inputs(labor, electricity, car and maintenance, and track) and uses unbalanced panel data consisted of annual observations on SSC, SMESRS and BUTA. The results show that the average annual growth rate of productivity of the three properties is 6.6 percent, which is 0.5 percent less than the average annual increasing rate of their labor price. They also show that the greatest part of the growth in productivity is explained by technical change and to a lesser degree by scale change and changes in productive efficiency though each of the three components contributes more than 20 percent to the growth in productivity, These results suggest that the three properties should base the increasing rate of their wages on the growth rate of their productivity and utilize existing technologies more efficiently prior to introducing new ones to raise their productivity, and that all the three components should be considered to evaluate their productivity more correctly.

• Journal of Trauma and Injury
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• v.27 no.3
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• pp.50-56
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• 2014

Purpose: Rollover motor vehicle crashes have a higher injury severity and fatality than other motor vehicle crash types. From a left-quarter turn rollover accident of 25-passenger bus, we intend to assess the injury of the occupant and the injury severities according to the occupants' position. Methods: We carried out the 3 steps investigation of occupants' interview, visiting the repair shop and using the police report. We analyzed injuries sustained by occupants, and compared injury severities considering column, row in occupant's position and passenger interaction Results: The rollover involved 14 passengers in the bus who were all old women except a man driver. The most common injury was in the upper extremity, with six occurrences being a left clavicle fracture. Major injuries including hemothorax and pneumothorax were diagnosed at left side of the occupant. In the comparison of injury severity among driver's column (left side), mid column and passengercolumn, ISS of passenger column was the highest ($9.9{\pm}7.4$, $8.8{\pm}5.5$, and $10.3{\pm}4.0$, respectively, p>0.05). The injury severity of multiple occupants by row was higher than that of single occupant (10.8 vs. 3, p<0.05). Conclusion: An occupant must fasten their seat belt to prevent an injury by passenger interaction in the left-quarter turn rollover accident of a bus.