• Journal of Korean Society of Transportation
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• v.31 no.1
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• pp.77-86
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• 2013

This paper focuses on the development of analytical models for estimating the changes in saturation flow rates (SFR) at the stop-lines of a signalized intersection due to the existence of nearby work-zones, and thereby calculating the prevailing capacity values for specific lane groups. Major changes were incorporated in the logics of previous models and significant revisions have been made to secure the accuracy and simplicity. Furthermore, much attention was paid to model validation by making comparisons to both extensive simulation results and empirical data from various sites. It was found that SFRs are highly sensitive to the location of work-zones, the distance to each work-zone from the stop-line of a concerned approach, the number of lanes open and closed, and the effective green time. Using such geometric and operating conditions that constitute work-zone environment, the proposed models successfully estimated SFR values with a miniscule margin of error.

• Current Optics and Photonics
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• v.3 no.3
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• pp.256-262
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• 2019

Extensive tumor resection accompanied by radiotherapy and chemotherapy is the standard of care for malignant gliomas. However, there is a significant obstacle to the complete resection of the tumor due to the difficulty of distinguishing tumor and normal brain tissue with a conventional surgical microscope. Recently, multiple studies have shown the possibility of fluorescence-guided surgery in malignant gliomas. The most used fluorescence dyes for brain tumor surgery are 5-aminolevulinic acid (5-ALA) and indocyanine green (ICG). In this paper, a new fluorescence guided operation system, which can detect both 5-ALA and ICG fluorescent images simultaneously, is presented. This operation system consists of light emitting diodes (LEDs) which emits 410 nm and 740 nm wavelengths. We have performed experiments on rats in order to verify the operation of the newly developed operation system. Oral administration and imaging were performed to observe the fluorescence of 5-ALA and ICG fluorescence in rats. When LEDs at wavelengths of 410 nm and 740 nm were irradiated on rats, 628 nm wavelength with a violet fluorescence color and 825 nm wavelength with a red fluorescence color were expressed in 5-ALA and ICG fluorescent material, respectively, thus we were able to distinguish the tumor tissues easily. Previously, due to the poor resolution of the conventional surgical microscope and the fact that the color of the vein is similar to that of the tumor, the tumor resection margin was not easy to observe, thus increasing the likelihood for cancer recurrence. However, when the tumor is observed through the fluorescence guided operation system, it is possible to easily distinguish the color with the naked eye and it can be completely removed. Therefore, it is expected that surgical removal of cancerous tumors will be possible and surgical applications and surgical microscopes for cancer tumor removal surgery will be promising in the future.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.109-116
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• 2022

The article is devoted to perfecting the system of management of the financial potential of transport enterprises. It is established that transport as an integral part of the state economy has to organically enter the market economy and provide sustainable transport services to national economy enterprises regardless of ownership, as well as ensure passenger transportation. It is also determined that in the conditions of market relations, transport highways must perform their functions with sufficient economic benefit to keep their material and technical resources in good order, conduct an investment policy with extensive use of scientific and technological progress, as well as a social policy guaranteeing the conditions for employees' motivated work. The study reveals an association between the financial and strategic goals of transport enterprises and the minimization of their economic risks, the prevention of bankruptcy and profit margin shortfalls. It is found that transport enterprises need to strive for the overall improvement of their financial potential through increasing the components of financial potential and assessing the impact of risk factors on them: the capacity of fixed assets, the capacity of financial resources, the capacity of services, and the capacity of credit opportunities. These are the elements of transport enterprises' financial potential that ensure its desired level. It is demonstrated that of critical importance in managing the financial potential of a transport enterprise is the role of financial resources, as a subject cannot reach the desired strategic goals without them.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.4
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• pp.337-344
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• 2021

Background: The primary indication for using long-acting anesthetics in dentistry is extensive dental procedures that require pulpal anesthesia beyond 90 min and management of postoperative pain. Ropivacaine is an amide local anesthetic that is available at various concentrations with inherent vasoconstrictive properties at low concentrations. Ropivacaine has a 75% greater margin of safety than bupivacaine. Ropivacaine can be a good alternative to bupivacaine as a local anesthetic in dental implant surgery as it provides a longer duration of both pulpal and soft tissue anesthesia after mandibular nerve block and lowers CNS and cardiovascular toxicity. This study aimed to evaluate and compare the clinical efficacy of ropivacaine and lignocaine for implant surgery anesthesia. Methods: Fifteen patients with bilateral edentulous sites indicated for implant placement were recruited for this study. Patients aged 20-60 years of both sexes were randomly recruited. Thirty implant placements were performed in the test and control groups using ropivacaine and lignocaine with adrenaline as local anesthetics, respectively. Results: The results were analyzed statistically. The duration of anesthesia was significantly higher in the test group than in the control group. Ropivacaine was found to be superior to lignocaine in terms of the quality of anesthesia. The comparison of mean visual analog scale scores showed ropivacaine to have better anesthetic and analgesic effects than the control group. Conclusion: Ropivacaine 0.75% provides a significantly longer duration of anesthesia than lignocaine 2% with adrenaline. Ropivacaine 0.75% decreased intraoperative and postoperative analgesia compared to lignocaine 2% with adrenaline. Hence, ropivacaine 0.75% can be used as an alternative to lignocaine in implant surgeries and other intraoral surgical procedures that require a longer duration of anesthesia and analgesia.

• Journal of Korea Trade
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• v.23 no.8
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• pp.1-26
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• 2019

Purpose - This paper investigates the recent trade collapse, recovery, and prolonged slowdown to shed light on the discussions about whether the current slowdown is structural or cyclical. I examine structural, cyclical, and heterogeneous aspects of the recent trade trends using detailed statistics of a small open economy, South Korea, whose economic success and growth have been heavily dependent on exports. Design/methodology - I use both aggregated and disaggregated trade statistics of South Korea. I apply the following methodologies: 1) I decompose the trade growth into the extensive and the intensive margin and observe the effect of prices over time. 2) I estimate the trade-income elasticities focusing on the world's import demand, separately for goods from the world and from Korea. 3) I compare the drop in goods exports in slowdown and trade collapse, which are the two unusual periods in the recent history when world trade has substantially dropped altogether. Findings - I show that while the last drop of trade after 2015 has cyclical aspects, there is evidence that the continued slowdown from 2012 is structural: 1) the so-called 'China factor' is found in the analysis of trade-income elasticity of the world and China for imports from Korea. 2) The bilateral trade barriers between Korea and its principal trading partners are universally tightening. 3) Firm sizes, destination countries, and the mode of transactions affect disaggregated trade flows during the slowdown periods. Originality/value - This paper contributes to the debate regarding whether the current trade slowdown is structural or cyclical. I provide two concrete evidence that the export drop in 2015 stems from low oil prices: one is the divergence of Korean export value index from its export quantity index, which started in late 2014 when oil prices plunged. I also contribute to the literature by providing evidence that Korea's trade barriers with important trading partners are steadily increasing since 2012 as the protectionist measures toward Korea's export products are steeply increasing after the global financial crisis.

• Earthquakes and Structures
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• v.21 no.5
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• pp.515-530
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• 2021

In a tall reinforced concrete (RC) core wall system subjected to strong ground motions, inelastic behavior near the base as well as mid-height of the wall is possible. Generally, the formation of plastic hinge in a core wall system may lead to extensive damage and significant repairing cost. A new configuration of core structures consisting of buckling restrained braced frames (BRBFs) and RC walls is an interesting idea in tall building seismic design. This concept can be used in the plan configuration of tall core wall systems. In this study, tall buildings with different configurations of combined core systems were designed and analyzed. Nonlinear time history analysis at severe earthquake level was performed and the results were compared for different configurations. The results demonstrate that using enough BRBFs can reduce the large curvature ductility demand at the base and mid-height of RC core wall systems and also can reduce the maximum inter-story drift ratio. For a better investigation of the structural behavior, the probabilistic approach can lead to in-depth insight. Therefore, incremental dynamic analysis (IDA) curves were calculated to assess the performance. Fragility curves at different limit states were then extracted and compared. Mean IDA curves demonstrate better behavior for a combined system, compared with conventional RC core wall systems. Collapse margin ratio for a RC core wall only system and RC core with enough BRBFs were almost 1.05 and 1.92 respectively. Therefore, it appears that using one RC core wall combined with enough BRBF core is an effective idea to achieve more confidence against tall building collapse and the results demonstrated the potential of the proposed system.

• Journal of the Korean Orthopaedic Association
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• v.55 no.3
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• pp.244-252
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• 2020

Purpose: Total femoral replacement (TFR) is an extreme form of limb salvage. Considering the rarity of this procedure, reports have focused on the complications and a proper indication is unclear. This study analyzed 36 patients with TFR who were asked the following: 1) prognostic factors related to survival in patients who underwent TFR with a tumoral cause; 2) overall implant and limb survival; 3) complications, functional outcome, and limb status for patients surviving for more than 3 years. Materials and Methods: According to the causes for TFR, 36 patients were categorized into three groups: extensive primary tumoral involvement (group 1, 15 cases), tumoral contamination by an inadvertent procedure or local recurrence (group 2, 16 cases), and salvage of a failed reconstruction (group 3, 5 cases). The factors that may affect the survival of patients included age, sex, cause of TFR, and tumor volume change after chemotherapy. Results: The overall five-year survival of the 36 patients was 31.5%±16.2%. The five-year survival of 31 patients with tumoral causes was 21.1%±15.6%. The five-year survival of 50.0%±31.0% in patients with a decreased tumor volume after chemotherapy was higher than that of increased tumor volume (p=0.02). The five-year survival of 12 cases with a wide margin was 41.7%±27.9%, whereas that of the marginal margin was 0.0%±0.0% (p=0.03). The ten-year overall implant survival of 36 patients was 85.9%±14.1%. The five-year revision-free survival was 16.6%±18.2%. At the final follow-up, 12 maintained tumor prosthesis, three underwent amputation (rotationplasty, 2; above knee amputation, 1), and the remaining one had knee fusion. Among 16 patients with a follow-up of more than three years, 14 patients underwent surgical intervention and two patients had conservative management. Complications included infection in 10 cases, local recurrences in two cases, and one case each of hip dislocation, bushing fracture, and femoral artery occlusion. Conclusion: Patients showing an increased tumor volume after chemotherapy and having an inadequate surgical margin showed a high chance of early death. In the long-term follow-up, TFR showed a high infection rate and the functional outcome was unsatisfactory. Nevertheless, this procedure is an inevitable option of limb preservation in selected patients.

• Economic and Environmental Geology
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• v.30 no.5
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• pp.395-406
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• 1997

Some RE (Zr, Nb, REE) ore deposits are located in the middle part of the Korean peninsula. Geotectonically, the RE ore deposits situated on the Kyemyeongsan Formation of northern margin of the Okcheon geosynclinal belt and in the transitional zone between Kyeonggi massif and Okcheon belt. The rare metal deposits distributed in Kyemyeongsan Formation which consists of schist and alkaline granite. The alkali granite has suffered extensive post-magmatic metasomatism and hydrothermal processes. The ore contains mainly Ce-La, Ta-Nb, Y, Y-Nb, Ti-Nb-(U), Nd-Th group minerals. Fergusonite, one of Nb-Y rich REE minerals belonging to the A-B oxides, is most common mineral in the rare metal deposits. The fergusonite bearing rocks may be devided into four types by occurrence features and mineral association, that is, zircon type, allanite vein, feldspar type, and fluorite type. Fergusonites show wide variations in optical properties, due to part of differences in their chemical composition (depending on the types), but also the degree of crystalinity of the individual specimens. Fergusonite metamicts enclosed in biotite are generally surrounded by well developed pleochroic haloes. Usually, fergusonite is accompanied with zircon and other REE-bearing minerals. Petrographical and chemical data are presented for fergusonites which collected different types. $Nb_2O_3$ and $Y_2O_3$ contents range from 48.51 to 53.01 wt.% and 29.18 to 42.02 wt.% respectively. Also, $ThO_2$, (1.83~6.93), $UO_2$, (0.17~2.84), ${\sum}RE_2O_3$ (except to Y) (1.11~8.73), and $TiO_2$, (0.19~1.19 wt.%) contents show variational compositions according to fergusonite types. The ${\sum}RE_2O_3$ of fergusonites are positive relation with $Y_2O_3$ and negative relaton with $ThO_2$ and $({\sum}{RE_2O_3}-{Y_2O_3})$. The $Nb_2O_3$ is sightly negative relation with $Ta_2O_3$. Back-scattered electron microscope images (BEI) of fergusonite show the mineral composition and textural feature is very complicated. The variation of Nb, Th and REE content of fergusonite and the modes of occurrence of mineral, suggests that REE may have been mobilized during the circulation of hydrothermal fluids related to contact metamorphism (metasomatism). The chemical variation of the fergusonites with occurrences and mineral association can be related to metasomatism of alkaline fluid was probably the dominant ore-forming process in Chungju district.

• Economic and Environmental Geology
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• v.51 no.2
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• pp.149-166
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• 2018

Many large earthquakes have continuously been reported and resulted in significant human casualties and extensive damages to properties globally. The accident of Fukushima nuclear power plant in Japan was caused by a mega-tsunami, which is a secondary effect associated with the Tohoku large earthquake (M=9.0, 2011. 3. 11.). Most earthquakes occur by reactivation of pre-existing active faults. Therefore, the importance of paleoseismological study have greatly been increased. The Korean peninsula has generally been considered to be a tectonically stable region compared with neighboring countries such as Japan and Taiwan, because it is located on the margin of the Eurasian intra-continental region. However, the recent earthquakes in Gyeongju and Pohang have brought considerable insecurity on earthquake hazard. In particular, this region should be secure against earthquake, because many nuclear facilties and large industrial facilities are located in this area. However, some large earthquakes have been reported in historic documents and also several active faults have been reported in southeast Korea. This study explains the evaluation methods of geological structures on active fault, fault damage zone, the relationship between earthquake and active fault, and respect distance. This study can contribute to selection of safe locations for nuclear facilities and to earthquake hazards and disaster prevention.

• Journal of Chest Surgery
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• v.29 no.10
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• pp.1118-1122
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• 1996

From January 1990 through December 1995, 43 patients underwent diaphragmatic plication for the management of phrenic nerve palsy .complicating various pediatric cardiovascular surgery. Their mean age at plication was 11.1 months and sex ratio was 31 males to 12 females. In order of decreasing incidence, the primary cardiovascular procedures included modified Blalock-Taussig shunt (7), total correction for the Tetralogy of Falloff (7), arterial switch operation (6), unifocalization for the pulmonary atresia with VSD (3), modified Fontan operation (3), VSD patch closure (3) and others. The involved sides of diaphragm were right in 17, left in 2) and bilateral in 3. Extensive pericardial resection with electocauterization of resected margin was thought to be the most common cause of phrenic nerve palsy (20). The interval between primary operation and plication ranged from the day of operation to 98 days (median 11 days). The methods of plication were central pleating technique(plication with phrenic nerve branch preservation) in 41, and other technique In 2. 10 patients died after plication (7: early, 3; late), and the causes of death were thought to be unrelated to plication itself. Among the 36 early survivors, extubation or cessation of positive pressure ventilation could be accomplished between 1 and 24 days postoperatively(mean : 4.5). Cumulative follow-up was 92 patient years without major complications. Postoperative follow-up fluoroscopy was performed in 6 patients, and the location and movement of plicated diaphragms were satisfactory in 5 patients. We concluded that diaphragmatic plication with preservation of phrenic n rve branch could lead to cessation of positive pressure ventilation and complete recovery of diaphragmatic function in the long term, unless the phrenic nerve was irreversibly damaged.