• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.225-230
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• 2005

At present, there are several problems related with sand mat which is used as a way to accelerate consolidation settlement, to act like an underground drainage layer and to increase trafficability simultaneously. First of all, the unbalance of the demand and supply of sand is one of the biggest problems, which causes not only price rise but also delay of the term of the total construction work. Secondly, the damage of ecosystem and scenery is triggered by thoughtless sand dredging or mining. So, the need that sand mat should be replaced with a new environmentally friendly material has been increased. Fiber mat may be one of the proper materials that suits the need. Therefore, we intended to compare the drainage properties of sand mat with those of fiber mat by experimental model tests. On the basis of the test results, fiber mat took shorter period of consolidation than sand mat and the amount of settlement in the farmer showed a little bit bigger than in the latter. As a conclusion, the substitutability of sand mat with fiber mat could be placed highly in view of drainage efficiency. Furthermore, when fiber mat is used, it has an advantage that spoiled soil of the construction site or nearby site can be used for the purpose of increasing trafficability in addition to a role of drainage layer.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.2
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• pp.71-78
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• 2014

There is a big risk of bullet impact because military rotorcraft is run in the battle environment. Due to the bullet impact, the rapid increase of the internal pressure can cause the internal explosion or fire of fuel cell. It can be a deadly damage on the survivability of crews. Then, fuel cell of military rotorcraft should be designed taking into account the extreme situation. As the design factor of fuel cell, the internal fluid pressure, structural stress and bullet kinetic energy can be considered. The verification test by real object is the best way to obtain these design data. But, it is a big burden due to huge cost and long-term preparation efforts and the failure of verification test can result in serious delay of a entire development plan. Thus, at the early design stage, the various numerical simulations test is needed to reduce the risk of trial-and-error together with prediction of the design data. In the present study, the bullet impact numerical simulation based on SPH(smoothed particle hydrodynamic) is conducted with the commercial package, LS-DYNA. Then, the resulting equivalent stress, internal pressure and bullet's kinetic energy are evaluated in detail to examine the possibility to obtain the configuration design data of the fuel cell.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.343-349
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• 2013

Crashworthy fuel cells have a great influence on improving the survivability of crews. Since 1960's, the US army has developed a detailed military specification, MIL-DTL-27422, defining the performance requirements for rotorcraft fuel cells. In the qualification tests required by MIL-DTL-27422, the crash impact test should be conducted to verify the crashworthiness of fuel cell. Success of the crash impact test means the improvement of survivability of crews by preventing post-crash fire. But, there is a big risk of failure due to huge external load in the crash impact test. Because the crash impact test itself takes a long-term preparation efforts together with costly fuel cell specimens, the failure of crash impact test can result in serious delay of a entire rotorcraft development. Thus, the numerical simulations of the crash impact test has been required at the early design stage to minimize the possibility of trial-and-error with full-scale fuel cells. Present study performs the numerical simulation using SPH(smoothed particle hydro-dynamic) method supported by a crash simulation software, LS-DYNA. Test condition of MIL-DTL-27422 is reflected on analysis and material data is acquired by specimen test of fuel cell material. As a result, the resulting equivalent stresses of fuel cell itself are calculated and vulnerable areas are also evaluated.

• Journal of KIISE:Information Networking
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• v.29 no.1
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• pp.24-30
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• 2002

Label switching technology is currently emerging as a solution for the rapidly growing of Internet traffic demand. Multiprotocol label switching(MPLS) is one of the standards made by the Internet Engineering Task Force(IETE) intended to enhance speed, scalability, and inter-opearability between label switching technologies. In MPLS, utilization of label space is a very important factor of network performance because labels are basic unit in packet switching. We propose a algorithm to effectively use label space by a multiple disconnect timer at the label switching router. Our algorithm is based on multiple utilization of the connection release timer over the MPLS network with multiple domains. In our algorithm, a relatively linger timeout interval is assigned to the traffic with higher class by the aid of the packet classifier. This reduces delay for making a new connection and also reduces the amount of packets which will be routed to the layer 3. Simulation results shows that reduction of required label number in MPLS network and this indicate our algorithm offers better performance than the existing ones in term of utilization of label space.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.3736-3741
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• 2015

Crash impact test is conducted to verify the crashworthiness of fuel tank. Success of the crash impact test means the improvement of survivability of crews by preventing post-crash fire. But, there is a big risk of failure due to huge external load in the crash impact test. The failure of crash impact test can result in serious delay of a entire rotorcraft development because of the design complement and re-production of the test specimens requiring a long-term preparation. Thus, the numerical simulations of the crash impact test has been required at the early design stage to minimize the possibility of trial-and-error in the real test. Present study conducts on the numerical simulation of phase I crash impact test using SPH supported by crash simulation software, LS-DYNA. Test condition of MIL-DTL-27422 is reflected on analysis and material data is acquired by specimen test of fuel cell material. As a result, the crash load on the skin material, overlap area and metal fitting is estimated to confirm the possibility of acquisition of the design load for the determination of the overlap area and adhesive strength.

• Journal of Medicine and Life Science
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• v.15 no.2
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• pp.95-100
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• 2018

We conduct this study to compare the difference in duration of labor in nulliparous women received epidural analgesia or non-epidural analgesia for labor pain. This retrospective, observational study based on the review of the medical records from February 2014 to July 2017. Epidural analgesia was initiated with a 10 mL epidural bolus of 1% lidocaine and was maintained with a 0.1% mixture of ropivacaine with fentanyl. Non-epidural analgesia was initiated with pethidine 12.5 mg bolus, followed by additional boluses as needed. The primary outcome was the duration of the labor. 149 healthy nulliparous women at term pregnancies with no evidence of fetal distress were enrolled in this study. 92 women received non-epidural analgesia (Group NE) and 57 women received epidural analgesia (Group E). There were no significant differences between the two groups in maternal demographic characteristics. Using a Kaplan-Meier survival analysis, there was no significant difference in the overall duration of the labor(P=0.233). The duration of the first stage of labor was $187.6{\pm}167.3min$ in Group NE, $248.6{\pm}168.7min$ in Group E (Mean${\pm}$SD, P=0.032). The duration of the second stage of labor was $67.1{\pm}57.8min$ in Group NE, $64.1{\pm}47.5min$ in Group E (Mean${\pm}$SD, P=0.693). Epidural analgesia delayed the first stage of labor in this study. But there were no significant differences between the two groups in the duration of the second stage and the total duration of labor.

• Plant Journal
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• v.18 no.3
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• pp.41-51
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• 2022

Recently, LNG power plants are increasing drastically and the desire of an improvement in the quality of life is growing. The delay of power plant construction can hinder the stability of power supply and increase the cost. So this study was conducted to help power plant construction progressing from now on by studying on the social acceptance of a LNG power plant. On this study I limited the scope of the study to the stage of Site Selection which is the most conflict stage and can interrupt the project. To conduct this study I researched the recently constructed power plants which have been delayed, in particular Eumseong Natural Power Plant and Daegu LNG Power Plant which are under bitter conflicts with local residents and have difficulty in construction progressing. So I found out that it is very important to collect the opinions of the residents in the stage of Site Selection and it is necessary to change ACT ON ASSISTANCE TO ELECTRIC POWER PLANTS- NEIGHBORING AREAS. Lastly it is very important to adapt the state-of-the-art facilities to increase the social acceptance of a LNG power plant.

• Korean Journal of Applied Biomechanics
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• v.32 no.3
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• pp.94-102
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• 2022

Objective: The purpose of this study was to investigate the effect of acute transcranial direct current stimulation (tDCS) on the isokinetic muscular endurance of the lower extremity for young adults. Method: Thirteen young adults performed isokinetic fatigue tasks for two experimental conditions including real tDCS and sham stimulation protocols. Before and after the task, the tensiomyography was used for evaluating muscle contraction characteristics of vastus medialis and semitendinosus. Paired t-test was performed to compare the fatigue index, changes in maximum radial displacement (∆Dm), delay time (∆Tc), and velocity of contraction (∆Vc) between tDCS conditions. Results: We found no significant differences in the fatigue index between real and sham conditions. In addition, the analyses identified no significant different values of ∆Dm, ∆Tc, and ∆Vc in the vastus medialis and semitendinosus between real and sham conditions. Conclusion: These findings suggest that the tDCS protocols may have no acute effect on lower limb muscle endurance for young adults. Future studies should consider the long-term effects of repetitive tDCS sessions, various stimulation positions, exercise tasks, and participant characteristics to more clearly understand the effect of tDCS on muscle endurance of lower extremities.

• Journal of Korea Trade
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• v.24 no.4
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• pp.49-70
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• 2020

Purpose - The UCP is recognized as the governing law for L/C transactions, but it covers only the general details of the transaction and does not cover all complex practices. In view of this limitation, this paper examines a negotiation transaction which is most actively utilized in L/C transactions via a thorough review of the UCP provisions, analyzes the problems of the negotiation clause in the UCP, and suggests appropriate countermeasures to deal with unnecessary litigation costs. By doing so, the parties involved in the negotiation transaction would be able to avoid financial costs such as having to pay for lawsuits. Design/methodology - The present study first differentiates the general types of L/Cs (e.g., sight payment L/C, deferred payment L/C, acceptance L/C, and negotiation L/C), explains and the Article 2 and Article 12(b) of the UCP 600 where the term 'negotiation' is used, digs into the drawbacks of 'negotiation' occurring under the UCP 600, and discusses solutions to the problems found by analyzing the drawbacks descriptively. Findings - After a review of the UCP provisions on negotiation in detail, several possible problems which may occur in practice were discovered. First, as the UCP stipulates, the negotiating bank will want to delay payment to the maximum extent possible and make payment on the banking day on which the issuing bank reimburses the amount. This may lead the beneficiary towards bankruptcy or put it in financial crisis. Second, when a fraudulent transaction occurs, the negotiating bank can neither request the issuing bank to reimburse nor can it exercise its recourse right against the beneficiary because it has obtained all the rights of the beneficiary by purchasing the documents. Third, there is a practice in which the beneficiary sells the documents to its transaction bank which is not the nominated bank if the nominated bank specified in the credit is located in a third country or the exporter has no relationship with the nominated bank in the credit. In this case, whether to accept this and reimburse the non-nominated negotiating bank entirely depends on the issuing bank's decision even though such practice frequently occurs in Korea. Originality/value - There has been little research effort pertaining to negotiation transactions in detail even though negotiation L/C transactions account for around 70% in world trade notwithstanding deferred payment L/Cs and acceptance L/Cs that are also negotiated in practice. Thus, if the negotiations clause under the UCP 600 provisions were reviewed and the drawbacks of the negotiation transactions most actively used in L/C transactions were identified and examined, specific countermeasures could ultimately help smoothen the operation of L/C transactions and prevent financial losses.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.221-228
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• 2021

Recently, there has been an increased awareness on the use of High-Intensity Focused Ultrasound (HIFU) as a non-surgical treatment option for leiomyomas. This study aimed to assess gynecologists' perception of HIFU therapy for uterine leiomyomas in Korea. We analyzed questionnaires from 162 Korean gynecologists who provided data on 1) demographics, 2) pattern of practice with respect to leiomyomas, and 3) opinion regarding HIFU therapy for leiomyomas. Of the 162 gynecologists, 2.8 % regarded HIFU as a first-line treatment for leiomyomas. HIFU was only available at the workplace of 19 % of respondents; of these, 58 % had requested the use of HIFU. When asked about their perception of HIFU for treating leiomyomas, only 19 % of the respondents thought that it was effective. The commonest perceived complication was a delay in the adequate treatment of sarcoma (59 %), followed by bowel injury (52 %). The respondents considered HIFU to be suitable in the following circumstances: age between 40 and 49 years, those patients who no longer desired pregnancy, medium-sized (5-6 cm) leiomyomas, and up to 2 leiomyomas. The Korean gynecologists' perception of HIFU as a treatment for leiomyomas is still not favorable. Gynecologists working at hospitals where HIFU is available tended to have a higher positive perception of this treatment. In addition to research involving a large number of gynecologists from multiple countries, a study on the long-term outcomes of HIFU is needed.