• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.5
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• pp.442-455
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• 2016

The resistance and seakeeping performance of a high-speed monohull vessel were investigated through a series of model tests in a towing tank. The hull had a slender wave-piercing bow, round bilge, and small deadrise angle on stern. Tests on the bare hull in calm water were first conducted and tests on spray rails followed. The spray rails were designed to control the flow direction and induce a hydrodynamic lift force on the hull bottom to reduce trim angle and increase rise of the hull. The maximum trim of the bare hull was $4.65^{\circ}$ at the designed speed, but the spray rails at optimum location reduced trim by $0.97^{\circ}$. The ship motion in head seas was examined after the calm water tests. Attaching the rails on the optimum location effectively reduced the pitch and heave motion responses. The vertical acceleration at the fore perpendicular reduced by 11.3%. The effective power in full scale was extrapolated from the model test results and it was revealed that the spray rails did not have any negative effects on the resistance performance of the hull, while they effectively stabilized the vessel in calm water and waves.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.159-175
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• 2007

The purpose of this study is to examine the causal relationship between trading volume of freight and industrial growth in Korea ports, and to induce policy implications. In order to test whether time series data is stationary and the model is fitness or not, we put in operation unit root test, cointegration test. And we apply Granger causality based on an error correction model, Hsiao(1981) method and variance decomposition. The results indicate that the extent of causality between trading volume of freight and industrial growth is strong in order of Incheon port, Busan port, Gwang Yang port, Ulsan port. We can infer policy suggestions as follows; The port policy of government must be focused on re-adjusting investment among Korea ports and raising competitive power of Korea ports

• Journal of rehabilitation welfare engineering & assistive technology
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• v.12 no.1
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• pp.46-52
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• 2018

The purpose of this study was to investigate the factors affecting falls in 107 elderly living in the city aged 65 or older by evaluating general characteristics, chronic disease status, medical variables related to falls, balance-related confidence, physical ability and depression. Also, the correlations between the significant differences in variables were identified, and the prediction power was determined by deriving the variables with high influence to induce the fall. In the faller group, urinary incontinence, foot pain, lower extremity weakness, number of chronic disease and medication use were significantly higher than those of the nonfaller group. Also, statistically significant differences were evaluated in ABC (Activities-specific Balance Confidence) score, BBS (Berg Balance Scale) score, SGDS (Short Geriatric Depression Scale), FRT (Functional Reach Test) value. The main correlated factor for fall was ABC score, the lower the ABC score, fall risk is increased which is a significant negative impact. When the evaluation is performed by combining those scales, the hit ratio to classify whether faller or nonfaller is increased to 70.01% which is quite higher value.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.8 no.1
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• pp.15-22
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• 2010

Purpose : This study examines the effects of pre-eccentric exercise and stretch ing to bicepsbrachii to prevent delayed onset muscle soreness and recovery of muscular function depending on the training intensity with 28 normal adults in their twenties. Methods : The subjects were divided into a control group, a group without any previous eccentric exercise, and a stretching group. Pre-eccentric exercise group conducted exercise with the intensity of 25% of maximal voluntary contraction. Pre-eccentric exercise and stretching was applied before to induce delayed onset muscle soreness and after, 24 hour post, 48 hour post, and 72 hour post. Measurements were conducted to examine pain and muscular function changes before, immediately after, and after inducing delayed onset muscle soreness. After inducing delayed onset muscle soreness, measurements were taken at the 24th hour, 48th hour, and 72nd hour. Results : The pre-eccentric exercise group and stretching group showed a significant difference from the control group by isometric contract ion power and mechanical pain threshold as a result of measuring delayed onset muscle soreness. Conclusion : From these results, electrical stimulation using presynaptic inhibition mechanism of transcutaneous electrical stimulation (TES) had positive effects for walking ability on inhibition of muscle tone in lower extremity. The motor level stimulation group experienced a more significant effect than the sensory level stimulation group. Therefore, the transcutaneous electrical stimulation (TES) is considered to be effective on walking ability increasing through inhibition of muscle tone in lower extremity for rehabilitation of post stroke hemiplegic patients.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.9
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• pp.823-828
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• 2013

To reduce the cost per watt of photovoltaic power, it is important to reduce the cell thickness of crystalline silicon solar cells. As the thickness of the silicon layer is reduced, two distinctive thermal expansion rates between the silicon and the aluminum layer induce bowing in a solar cell. With a thinner silicon layer, the bowing distance grows exponentially. Excessive bowing could damage the silicon wafer. In this study, we tried to measure an irregularly curved silicon solar cell more accurately using a 3D image scanner. For the detailed analysis of the three-dimensional bowing shape, a least square fit was applied to the point data from the scanned image. It has been found that the bowing distance and shape distortion increase with a decrease in the thickness of the silicon layer. An Ag strip on top of the silicon layer can reduce the bowing distance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.149-155
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• 2016

Early detection of toxic gases, such as volatile organic compounds (VOCs), is important for safety and environmental protection. However, the conventional detection methods require long-term measurement times and expensive equipment. In this study, we propose a thin-film-type chemical sensor for VOCs, which consists of self-assembled monosize nanoparticles for 3-D photonic crystal structures and polydimthylsiloxane (PDMS) film. It is operated without any external power source, is truly portable, and has a fast response time. The structure color of the sensor changes when it is exposed to VOCs, because VOCs induce a swelling of the PDMS. Therefore, using this principle of color change, we can create a thin-film sensor for immediate detection of various types of VOCs. The proposed device evidences that a fast response time of just seconds, along with a clear color change, are successfully observed when the sensor is exposed to gas-phase VOCs.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.508-514
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• 2004

A fluxgate magnetic sensor consists of a solenoid excitation coil, pick-up coil, and magnetic core. We presents the effect of magnetic core shape in a micromachined fluxgate sensor. To observe the performance of fluxgate sensor with magnetic core side width and gap, side width of 125 ${\mu}{\textrm}{m}$, 250 ${\mu}{\textrm}{m}$, and 500 ${\mu}{\textrm}{m}$ were designed in a rectangular-ring shaped core and the gaps of 0 ${\mu}{\textrm}{m}$, 50 ${\mu}{\textrm}{m}$, and 100 ${\mu}{\textrm}{m}$ were also fabricated in a racetrack shaped core. The solenoid coils and magnetic core were separated by benzocyclobutane(BCB) which had high insulation and good planarization characters. Copper coil patterns of 10 ${\mu}{\textrm}{m}$ width and 6${\mu}{\textrm}{m}$ thickness were electroplated on Ti(300 $\AA$) / Cu(1500 $\AA$) seed layers. 3 ${\mu}{\textrm}{m}$ thick N $i_{0.8}$F $e_{0.2.}$(permalloy) film for the magnetic core was also electroplated under 2000 gauss to induce the magnetic anisotropy. The magnetic core had the high DC effective permeability of ∼1,300 and coercive field of ∼0.1 Oe. Because the magnetic cores of 500 ${\mu}{\textrm}{m}$ side width and 0 gap had a low magnetic flux leakage, high sensitivity of ∼350 V/T were measured at excitation condition of 3 $V_{P-P}$ and 2 MHz square wave. The power consumption of ∼14 ㎽ was measured. The fabricated fluxgate sensor had the very small actual size of 3.0${\times}$1.7 $\textrm{mm}^2$. When two fluxgates were perpendicularly aligned in terrestrial field, their two-axis output signals were very useful to commercialize an electronic azimuth compass for the portable navigation system.m.m.m.

• The Journal of Korean Medicine
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• v.23 no.2
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• pp.180-189
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• 2002

Background and Purpose : The hemiplegic upper extremity is affected in many stroke patients, and recovery is often poor. The purpose of this study was to assess the efficacy of electroacupuncture (EA) in enhancing the upper extremity motor and functional recovery of ischemic stroke patients. Subjects and Methods : Forty ischemic stroke patients (the upper extremity Fugl-Meyer motor scale (FM) score lower than 46, lesion location within middle cerebral artery territory) within 2 weeks of stroke onset were randomly allocated to either an EA group that received EA treatment or a control group that received only routine ward care. The EA was applied at Quchi-Shousanli (LI11-LI10), Waiguan-Hegu (TE5-LI4) points on the hemiparetic side six times per week for 4 weeks. The frequency of stimulation was 25-50Hz and the intensity was set at a level sufficient to induce muscle contraction. EA treatment was given for 30 minutes and all patients of both groups received standard rehabilitation program. Outcomes were assessed, in a blind manner, before treatment began and at 4 weeks after treatment, with the FM, the Motor Power score (MP) for shoulder/elbow, and the subsection of the Modified Barthel Index (MBI) for drinking/feeding/dressing upper body/grooming. Results : These 2 groups had comparable clinical characteristics, lesion location, lesion size, and pretreatment impairment scores. By the end of treatment, the EA group showed significantly more improvement than the control group in the subsection of the FM for shoulder/elbow/coordination (6.4 vs. 3.7; P=0.047) and the MP for shoulder/elbow (5.3 vs. 3.3; P=0.008). The subsection scores of the MBI for drinking/feeding/dressing upper body/grooming were not significantly different between two groups. No adverse effects due to treatment were found Conclusion : These results suggest that EA enhances the upper extremity motor recovery of acute stroke patients. However, this study failed to demonstrate any significant functional benefit related with upper extremity. Future study should be carried out in a larger sample size and use the functional outcome measure that is more specific and sensitive to the upper extremity.

• Environmental and Resource Economics Review
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• v.25 no.2
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• pp.229-253
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• 2016

To achieve the socially optimum level of renewable generation, governments should design renewable policies to induce renewable technologies competitive with conventional generation technologies. And to do that, it is needed to understand how each policy has been effective in promoting renewables for power sector. In most of the literatures, there are two key limitations that they did not considered autocorrelation problem using the amount of generation from renewables as a dependent variable and technology innovation which needs to be preceded technology adoption. In this study, I try to overcome these two problems by using dynamic panel model and adding an additional variable for technology innovation. According to the result, FIT has been effective rather than RPS in promoting renewables for generation and I found the possibility that the counterintuitive results which commonly appeared in existing studies might be due to the two limitations mentioned above.

• The Journal of Internal Korean Medicine
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• v.31 no.2
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• pp.290-297
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• 2010

Objectives : This study evaluated the effect of Dioscoreae Rhizoma on antioxidant and antimicrobial activity in vitro. Methods : In vitro experiments were made on antioxidant by DPPH radical scavenging activity, enzyme activity of SOD, protective effect about $H_2O_2$ and DNA fragmentation in RAW264.7 cells, as well as antimicrobial by Cox-2 expression in LPS-induced RAW264.7 cells. Results : 1. Dioscoreae Rhizoma's antioxidant ability was improved by DPPH radical scavenging activity. 2. Antioxidant ability of Dioscoreae Rhizoma produced good results at more than 0.025 mg/$m{\ell}$. 3. On protective effect of Dioscoreae Rhizoma about $H_2O_2$ on RAW264.7 cells, with addition of Dioscoreae Rhizoma extract the cells' survival increased compared to adding $H_2O_2$ only. 4. About revelation-control of Cox-2 at RAW264.7 cells which induce by LPS, when Dioscoreae Rhizoma's concentration was higher from 0.0125 mg/$m{\ell}$ to 1 mg/$m{\ell}$, its control activity was stronger. Thus we found Dioscoreae Rhizoma has antimicrobial activity. 5. The power of DNA fragmentation control of Dioscoreae Rhizoma was time-independent. Conclusions : From this study we conclude that Dioscoreae Rhizoma has effects on antioxidant and antimicrobial activity. However, considerable work still needs to be done studying antioxidants by concentration, as well as a variety of experiments about antimicrobial activity.