• Aerospace Engineering and Technology
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• v.2 no.1
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• pp.171-181
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• 2003

The nose fairings of KSR-III are designed to be separated from the rocket by explosive force at the mission altitude to expose the payload. Adequate amount of separation force should be imposed to allow safe separation without collision between the fairings and the rocket, and the separation device was designed for the separation at very high altitude where almost no air load was expected. As the development of KSR-III goes on, several design changes have made and lower separation altitude of 45km is expected as a result. Under these circumstances, it is required to determine if the nose fairings can be separated without collision with much severer air load than for the design condition. In this study, the 6-DOF motion analysis program, PASEM, which was developed to predict the strap-on booster separation, is modified to simulate the pivotal motion of the fairings at early stages of separation. The accuracy of pivot motion simulation is validated by comparison with the results of ground test and the accurate separation conditions are deduced from it. Trajectory simulations are performed to see if separation without collision is possible with varying angle of attack, direction of gravity, and the effect of gust. It is also found that reducing the separation angle of the clamshell hinge from 60 degrees to 40 degrees can enhance separation safety and separation at lower altitude of 40km can be done without collision.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.3
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• pp.60-66
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• 2006

The purpose of this paper is to evaluate potential application of Lightweight Piezo-composite Actuator (LIPCA) to suppress vibrations of structures. The LIPCA, consisting of a piezoelectric layer, a carbon/epoxy layer and glass/epoxy layers, has advantages in terms of high performance, durability and reliability, compared to the bare piezoelectric ceramic (PZT) actuator. We performed two kinds of experiments on static actuation and active vibration suppression to investigate the actuation performances of the LIPCA and the bare PZT. We attached the actuator on one side and a strain gage on the other side of an aluminum beam. In the static actuation test, we evaluated the performance by comparing equivalent actuation moments of the LIPCA and the bare PZT due to the applied voltage. In the active vibration control test, control signals were generated to suppress the vibration of the beam by the PID control algorithm based on the measured strain signals. The performances were estimated based on settling times of the strain responses. It can be concluded that the LIPCA has better actuation performances than the bare PZT in active control of free vibration as well as static actuation.

• Korean Journal of Breeding Science
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• v.43 no.4
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• pp.297-303
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• 2011

In order to confirm the biological activities of rice bran and hull, total phenolic content, antioxidant and anticancer activities were examined in three rice varieties that have different seed coat colors such as brown, black, and purple. The antioxidant activity was measured by free radical scavenging assay including DPPH, $ABTS^+$ and reducing power activity. The anticancer activity was evaluated by WST assay with human HepG2 cell lines. As the result, Huegjinju, black seed coat rice, showed higher of the total phenolics contents in both bran and hull, than purple Jeojinju and brown Ilpum. In the antioxidant activity, Heugjinju showed the highest among the bran extracts, but the activities of hull extracts were similar in three varieties. In the anticancer activity to HepG2 cell line, the hull extract was 20% higher than that of bran extract in the average of three varieties. The hull extracts of Ilpum and Jeokjinju showed similar anticancer activites about 92%, and that of Heugjinju showed the lowest activity of 30.4%. The anticancer activities of hull extracts in three varieties showed positive correlation with total phenolics contents, DPPH radical scavenging activities and reducing power activities. In conclusion, the rice bran and hull showed potent antioxidant and anticancer activities varied in three varieties that have different seed coat colors.

• Korea Trade Review
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• v.41 no.3
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• pp.1-25
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• 2016

This study reviews international discussions about the trade-labor linkage and examines the labor chapters of FTAs enforced by the US and the EU from a comparative perspective. Since early 1990s, starting from the NAFTA, the US has included forceable labor provisions in its FTAs and this trend continues to the TPP which was concluded in October 2015. On the other hand, the EU's labor provisions in its FTAs have been composed of promotional elements on labor rights based on cooperations and dialogues. These different features of labor provisions in the US and European FTAs are mainly due to the motives of the FTAs of the US and the EU respectively as well as their domestic situations with regards to domestic law and institutional set-ups. The coordination of labor provisions involves a long-term institutional as well as regulatory convergence which triggers not only economic but also social changes, compared to a relatively short-term effect of tariff elimination. For Korea which has been a FTA partner country both with the US and the EU, it is significant to keep the different characteristics in the labor provisions in mind, particularly in the process of its implementation. Concerning the implementation of Korea-US FTA, it might be problematic if Korean law and its regulatory practice on labor-management relations do not comply with that of the US. The Korea-EU FTA case can also have an indirect impact on Korea's labor laws since it stipulates in its provisions that both parties should have discussions not only within each government but also with the civil communities including NGOs. Thus, Korea should pay more attention to the true meaning in labor provisions of both FTAs in order to promote its firms to be equipped with the right labor-management system in their operations abroad.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.21-30
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• 1985

The tension leg platform (TLP) is a kind of compliant structures, and is also a type of moored stable platform with a buoyancy exceeding the weight because of having tensioned vertical anchor cables. In this paper, among the various kinds of tension leg structures, Deep Oil Technology (DOT) TLP was analyzed because it has large-displacement portions of the immersed surface such as vertical corner pontoons and small-diameter elongated members such as cross-bracing. It also has results of hydraulic model tests, comparable with theorectical analysis. Because of the vertical axes of symmetry in the three vertical buoyant legs and because there are no larger horizontal buoyant members between these three vertical members, it was decided to develop a numerical algorithm which would predict the dynamic response of the DOT TLP using the previously developed numerical algorithm Floating Vessel Response Simulation (FVRS) for vertically axisymmetric bodies of revolution. In addition, a linearized hydroelastic Morison equation subroutine would be developed to account for the hydrodynamic pressure forces on the small member cross bracing. Interaction between the large buoyant members or small member cross bracings is considered to be negligible and is not included in the analysis. The dynamic response of the DOT TLP in the surge mode is compared with the results of the TLP algorithm for various combinations of diffraction and Morison forces and moments. The results which include the Morison equation are better than the results for diffraction only. This is because the vertically axisymmetric buoyant members are only marginally large enough to consider diffractions effects. The prototype TLP results are expected to be more inertially dominated.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.49-59
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• 2004

In order to be a hub-port in Northeast Asia, current China government has intensively invested in port development. Further, this development Project is significantly big scale, compared with those projects which Korea and Japan have. Thus, China is beginning to threaten Korean ports, especially Busan port which try to be a hub port in Northeast Asia. For this reason, recently many studies to evaluate competitiveness between Korean ports, especially Busan and Gwangyang, and Chinese ports have been conducted. In the mean time, implications of those pervious research has mainly been based on evaluation of port competitiveness using evaluation methodologies, such as AHP(Analytical Hierarchy Process) and HFP(Hierarchical Fuzzy Process). However, as previous evaluation algorithms are methodologies that only calculate ranking of ports by competitiveness level, from the results of analysis, critical weak points affected current port competitiveness could not clearly fine out. That is, because there has not been any algorithm that can extract critical points from the evaluation results. The aim of this paper is to present critical points that affect port competitiveness using an algorithm based on IRFE(Inverse Relation of Fuzzy Evaluation), and scenario analysis, from previous results of evaluation of port competitiveness. And The research scope is to covey the subjective ports of Korea and China's 7 major ports (Busan, Gwangyang, Sanghai, Qingdao, Tienjin, Dalian and Kaoshuing). From analysis, it was found that critical weak point of Busan port is the level of hinterland including availability of free trade zone.

• Korean Chemical Engineering Research
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• v.48 no.6
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• pp.690-694
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• 2010

In this study, herbal wood vinegar including Bambusoideae, Cinnamomi Cortex, Zingiberis Rhizoma was tested to see possibility for cosmetic or skin related medicine. Anti-oxidation effect of herbal wood vinegar was tested by DPPH free radical scavenging activity, and showed 97% inhibition rate at $50{\mu}g/ml$. Anti-bacterial effect was tested by disc diffusion method, and it indicated strong anti-bacterial activity against normal skin flora Staphylococcus aureus. Whitening effect was measured by tyrosinase inhibition assay, and it was lower compared with vitamin C. Stability test was done by MTT assay, and cell toxicity was relatively high. Stability was also checked, and there was not significant change in color, aroma, appearance and pH during storage. Anti-atopic dermatitis test was done by hairless mouse and herbal wood vinegar recovered damaged skin to almost normal condition after 9 days of application. IgE concentration in herbal wood vinegar treated mouse was also reduced 30% compared with control. From the study, herbal wood vinegar showed good anti-oxidation, anti-bacterial and anti-atopic dermatitis effect, and had promising application in cosmetic or skin related medicine.

• The Korean Journal of Applied Statistics
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• v.23 no.1
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• pp.81-93
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• 2010

Korea experienced a financial crisis in 1997. Since then Korea economy has undergone severe change such as exchange rate regime from the market average exchange rate system to the free floating exchange rate system in 1997, and the currency rate fluctuation has been widening. We empirically analyze the determination of the Won/Dollar exchange rate based on the monetary approach. We employ Lucas (1982), Bilson (1978) and Frankel (1979) models and consider some mixed models. We make use of monthly data of money supply, income, interest rate, capital balance, terms of trade, and the yen/dollar exchange rate over the period 1990-2009. We compare the empirical results of cointegration tests and the vector error correction model(VECM) from the two regimes, the pre and post korean financial crisis. The won/dollar exchange rate has long-run relationship with the variables in the monetarist models in the two regimes. For the post crisis regime, the Bilson model is the best and the long run variables also affect the short run dynamics of the won/dollar exchange rate.

• Journal of Korea Port Economic Association
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• v.24 no.2
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• pp.175-192
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• 2008

Today's individual firms no longer compete as solely autonomous entities, but rather as supply chain. As such the competitive position of a port is not only determined by its internal strengths but also it is also affected by its links in a global supply chin. In other words, port competitiveness is becoming increasingly dependent on external coordination and control of the whole supply chain. The main purpose of this paper is to examine how a port embeds itself into supply chain in order to strengthen its competitive position by focusing on Dubai port case. This paper found that Dubai port used three phases-insertion, integration and dominance-as a strategies for how it can embedded into global supply chain successfully. Dubai's global supply chain strategies give some implications for the further development of the Port of Gwangyang. First, the Port of Gwangyang should fully utilize symbiotic relationship with Gwangyang free Economic Zone. Second, the integration between Korea Container Terminal Authority and GYFEZ can be recommended for fast decision-making and providing a one-stop-service. Finally, Gwangyang should pursue an aggressive supply chain strategy, aims at dominance in the regional port network through port alliance with small and medium ports in neighboring area.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.74-74
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• 2011

본 연구에서는 중앙경간 54m, 교폭 4m의 사장교형식의 보도교로 측경간은 계단으로 이루어진 1경간 케이블교량을 대상으로 보행하중에 의한 수직진동을 제어하기 위해 제진장치(TMD)를 적용하기로 하고 실물 TMD의 설계 및 제작 그리고 설치 및 제어성능실험을 수행하였다. 우선 사장교형식의 교량. 그리고 1경간 교량이라는 점에서 상대적으로 감쇠율이 낮을 것으로 예측되었고 또한 54m의 경간장이 보행자가 가진 주파수에 근접한 고유진동수를 나타낼 것으로 사료되어 Eurocode 2 part 2(EC5-2)의 규준에 따라 1인 및 다수 보행하중에 의한 보도교의 발생가속도를 산출하였다. 이 경우 최대가속도는 다수의 보행자가 연속적으로 진행할 때 발생하였으며, 수직방향의 가속도가 사용성기준을 초과하는 것으로 나타났다. 또한 구조해석프로그램에 의한 고유치 해석결과, 보행하중의 주파수대역내에 진동모드가 존재하는 것으로 나타났다. 따라서 본 교량의 설계단계에 있어서 보행진동을 제어하기 위하여 유지관리가 용이한 수동형의 동조질량감쇠장치(Tuned Mass Damper)를 적용하기로 하였으며 TMD의 설계에서는 TMD의 제어목표를 만족시킬 수 있는 TMD의 가동질량(moving mass)을 우선적으로 결정하였고, 이로부터 Den Hartog의 제안식에 따라 TMD의 고유진동수비, 유효감쇠비를 산정하였다. 산정된 변수들을 이용하여 설계된 TMD는 현장설치 및 튜닝의 편의성을 고려하여 수평 외팔보형식으로 설계, 제작되었으며 제작된 TMD의 경우 회전축에 대해 질량, 스프링, 댐퍼의 중심거리를 조정함으로써 TMD의 진동수, 강성, 감쇠력을 상대적으로 매우 용이하게 조절할 수 있으며, 조정범위 또한 광범위하여 일반 TMD에 비해 현장설치시 대상구조물에 동조시키기가 용이하며, 작동시 마찰감쇠가 거의 없다는 장점이 있다. 현장설치전에 제작된 TMD를 대상으로 자유진동 시험을 통하여 질량의 중심거리, 스프링 크기 그리고 댐퍼의 설치유무를 각각 변화시키며 TMD의 자유진동 데이터를 취득하였다. 각각의 시험에서 얻어진 데이터로부터 스펙트럼해석을 통하여 고유진동수를 구하였고, 자유진동 파형으로 부터 감쇠비를 구하였다. TMD는 일반적으로 제어모드의 변형형상이 가장 큰 곳에 설치되었을 때 최대의 제진효과를 발휘할 수 있다. 그러나 현장여건상 설치가 불가능하거나 미관을 해치는 경우에는 가능한 범위 내에서 TMD 제어효율이 가장 크게 발휘할 수 있는 곳을 선택하여야 한다. 본 보도교의 경우, 중앙경간 중심부에서 가장 큰 모드변형형상을 나타내지만, 보도교의 상판 연결부 등에 따른 TMD 시공문제로 인하여 TMD 설치위치는 교량 중앙에서 양 방향으로 1.25m 떨어진 곳에 대칭으로 총 2기를 설치하기로 하였다. 일반적으로 TMD의 모든 설계변수는 구조물의 설계단계에서 수행된 구조해석결과에 근거하여 설정하므로 완공된 구조물, 즉 실제보도교의 동적특성을 계측하여 정확하게 진동수를 튜닝하여야 한다. 구조해석에 의한 보도교의 수직방향(TMD 작동방향) 고유진동수는 1.5225 Hz이며, 감쇠비는 규준에 의하여 0.6 %로 가정하였다. 그러나 이 값들은 구조해석모델 및 재료적 특성과 시공상의 오차에 의하여 실제와 다를 수 있으므로 현장계측에 의한 확인이 요구된다. 또한 TMD의 제진효율이 설계시의 목표대로 확보되었는지도 확인해야 하므로 현장튜닝 및 성능시험을 실시하였다. 보도교의 가진은 사전에 실시한 상시 미진동계측결과를 토대로 2Hz를 목표로 하여 인력가진실험을 수행하였고, 탁월진동 주파수는 1.9896Hz로 나타나 구조해석결과와 오차가 있음을 알 수 있다. 가진실험결과를 토대로 TMD의 진동수를 최적진동수비로 튜닝하고 인력가진 실험을 다시 실시하여 TMD의 진동제어성능을 검토하였다. TMD 튜닝 전, 후의 보도교 감쇠비를 비교한 결과, TMD를 설치함으로써 약 4.218%의 감쇠비 증가가 있음을 알 수 있다.