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In general, an autotransformer (AT) is used to improve the voltage sag and inductive interference in power lines and communication lines in the Korean ac electric railway feeding system. In particular, the Korean AT feeding system has a different configuration compared to those of the other countries, such as Japan or France; therefore, it has certain distinctive characteristics. However, a fault locator imported from the other countries has been used in Korea, and the settings of these equipment should be modified and reflect the distinct characteristics of the Korean AT feeding system. Thus, the development of a novel fault-location scheme for the Korean railway system is required. Herein, we analyzed the fault current and developed a specific relationship for use in our new algorithm. We presented the current magnitude of each branch, expressed by the boosting current of the ATs; further, the novel fault-location scheme using this relationship is developed. The novel scheme performance is verified through power system computer aided design/electromagnetic transients including DC (PSCAD/EMTDC) and the field measured data.

We conjecture that the presence of short-term institutional investors exacerbates agency conflicts between shareholders and creditors because short-term institutions might force firm managers to take myopic actions. Using the data on private debt to U.S. firms, we find that the investment horizons of institutional investors are negatively correlated with the number of loan covenants and loan spreads. We also document that short-term (long-term) institutional ownership is positively (negatively) correlated with the number of covenants, and that banks charge higher spreads on loans issued to firms with more short-term institutional ownership. These findings are consistent with our conjecture.

The flow characteristics of a sweeping jet ejecting from a typical feedback channel fluidic oscillator were investigated using time-resolved particle image velocimetry. The three-dimensional flow structure of the jet was examined through the instantaneous and averaged velocity fields measured at the streamwise center plane and cross-sectional planes of the jet for a range of Reynolds numbers (8000, 12,000, 16,000, 20,000, and 24,000). As the Reynolds number increases, the frequency of the sweeping jet linearly increases from 0.7 to 2 Hz. However, the switching time of the jet flow direction from one side to the other is very short compared to the sweeping period. As a result, the ensemble-averaged flow patterns of the sweeping jet at the streamwise center plane look like twin jets issued from a V-shaped nozzle, regardless of the Reynolds number. The rapidly switching jet contains a counter-rotating vortex at the cross-sectional plane of the jet near the nozzle, similar to a cross-flow jet. The coherent vortex structures are rapidly destroyed and become random when the jet moves downstream.

본 연구는 2014년 11월 후강통 시행으로 인한 중국 자본시장의 전면 개방이 국제분산투자의 효과에 미치는 영향을 분석하였다. 이를 위해 후강통 시행 전후 5개국(한국, 미국, 일본, 홍콩, 중국) 주요주가지수들 간의 상관관계, 공적분 관계를 분석하였다. 또한 후강통 시행으로 인한 위험분산효과 및 위험 대비 수익률의 변화를 살펴보았다. 분석 결과, 후강통 시행 이후 중국시장의 홍콩 및 미국시장과의 동조화는 강화된 반면, 한국 및 일본시장과의 동조화는 약화되는 것으로 나타났다. 아울러 5개국 모두를 포함하는 포트폴리오의 변동성은 후강통 시행 이후 증가하였다. 반면 중국시장과 4개국 간 포트폴리오들의 샤프지수는 후강통 시행 이후 모두 향상되었다. 이는 후강통 시행 이후 포트폴리오의 변동성 변화 대비 수익률의 상대적 증가로부터 기인한 것으로 보인다. 본 연구의 결과는 후강통 시행이 국제 포트폴리오의 위험분산효과를 약화시키는 경향을 보여주지만, 위험 대비 보상의 관점에서는 분산투자에 긍정적 영향을 끼칠 수 있음을 시사한다.

Conventional Kelvin-cell-based metal foam (KMF) has triangular or circular struts. This study proposes a KMF with elliptical struts instead of such struts. Two schemes of transforming a circular strut into an elliptical strut are proposed: (1) maintaining the same circumference as the circular strut cross-section and (2) maintaining the same cross-section area as the circular strut cross-section. Five KMFs with different struts were designed. The fluid flow, heat transfer, and performance characteristics of the KMFs were numerically investigated. Two dimensionless diameters for the strut section are introduced to analyze the hydro-thermal characteristics of KMFs: λa, the major diameter ratio of the elliptical strut to the circular strut, and λb, the minor diameter ratio of the elliptical strut to the circular strut. The major axis of all struts was set parallel to the main flow direction. The pressure drop and heat transfer characteristics of KMFs are explained by the pressure drag and friction drag. As λb decreases from 1.000 to 0.556, the pressure drop of the KMF decreases by 44% because the pressure drag and blockage ratio decrease with λb. However, the decrease of λb results in decreases in the free stream velocity around the strut, which has a penalty on the heat transfer performance. This can be partially compensated by increasing λa by increasing the flow tortuosity, surface area, and separation angle. Therefore, using the scheme with the same cross-sectional area provides better performance than using the scheme with the same circumference. A KMF using the scheme with the same cross-section area scheme required 32% less pumping power than a KMF with circular struts and the same thermal resistance.

Lee, Y.B.; Kim, H.D., and Kwak, K., 2018. Verification of Beach Erosion in West Coast of Korea. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 256–260. Coconut Creek (Florida), ISSN 0749-0208.The factors that cause the coastal erosion are different depending on where the wave field dominates and where the tide effect is large; however, most coastal erosion studies have been conducted on areas where waves are dominant. The west coast of Korea has maximum tide difference of more than 9 m. This study aided to examine the relationship between coastal erosion and the area where the effect on tide is large. The selected study field, Kkotji Beach, is a representative coastal tourist location on the west coast of Korea. Due to serious coastal erosion, sandy beach has been graveled and the number of tourist has decreased which resulted in great economic loss. In this study, field observations and numerical simulations were used simultaneously. For the field observations, beach profile measurement, sediment observation, wave observation, and tide and current observations were conducted to investigate and analyze the causes of the coastal erosion. Numerical simulations were used to consider both wave and tide by reproducing the coastal erosion phenomenon and compare to the field observations. The effects of the tide on coastal erosion were presented through the simulations. As a result, the suspected causes of the erosion of the Kkotji Beach are the W direction induced wave during the winter, reduction of the erosion control forest due to coastal development, and large tide difference.

This study was conducted to investigate the quality characteristics and changes in isoflavone content of Cheonggukjang with added Chaga mushroom by secondary fermentation at 40℃ for 48 h with or without a starter, Lactobacillus acidophilus KCTC 3925. Cheonggukjang samples were divided into three groups: Control (unsterilized Cheonggukjang fermented without a starter), NS (unsterilized Cheonggukjang inoculated with L. acidophilus KCTC 3925), and YS (heat-sterilized Cheonggukjang inoculated with L. acidophilus KCTC 3925). The approximate composition of the three types of Cheonggukjang was 49.79-51.44% moisture, 4.54-4.72% crude ash, 43.21-44.37% crude protein, 11.58-13.65% crude fat, 37.41-40.07% carbohydrate, 31.92-33.82% dietary fiber. The mineral content included 5.43–9.64 mg% Na, 1,792.86–1,824.39 mg% K, 253.69–326.09 mg% Ca, 619.37–691.20 mg% P, 92.59–110.59 mg% Fe, and 0.01–0.02 mg% Cd. Free amino acid contents of NS (2,520.92 mg%) and YS (2,421.94 mg%) were significantly higher than that of the control (2,236.76 mg%). Amino-type nitrogen content for the three types of Cheonggukjang ranged from 837.20-920.27 mg% with no significant difference. Ammonia-type nitrogen content ranged from 137.09-169.36 mg%. Supplement of Cheonggukjang with L. acidophilus KCTC 3925 increased production of aglycone isoflavons compared to that of control. Therefore, our results show that fermenting Chaga Cheonggukjang with L. acidophilus KCTC 3925 leads to improved quality characteristics and increased isoflavone aglycone content.

Background Recently, resistance expiratory muscle strength training (EMST) has been reported as a remedial treatment for dysphagia. Objective To investigate the effect of resistance EMST on the swallowing function in stroke patients with oropharyngeal dysphagia. Methods Forty-two stroke patients with dysphagia were randomly assigned to two groups: an experimental group (n = 13) and a placebo group (n = 13). The experimental group performed EMST using a portable EMST device, while the placebo group performed EMST using a sham EMST device with no loading. The intervention was performed 5 days per week for 4weeks, in five sets of 5 breaths through the device for a total of 25 breaths per day. Both groups underwent conventional dysphagia treatment for 30 minutes/day, 5 days/week, for 4 weeks. Videofluoroscopic dysphagia scale (VDS) and penetration-aspiration scale (PAS) based on a videofluoroscopic swallowing study (VFSS) were assessed to analyze the oropharyngeal swallowing function. Results The experimental group showed more improvement in pharyngeal phase of the VDS (p = 0.018 and 0.006, respectively) and PAS compared to the placebo group (p = 0.014). Conclusions We suggest that EMST could improve the effects of dysphagia observed in post-stroke elderly patients based on swallowing function.

BACKGROUND Dysphagia after stroke can cause a variety of complications, especially aspiration pneumonia, which can be life-threatening. Therefore, rehabilitation methods to reduce aspiration in patients with dysphagia are important. OBJECTIVE In the present study, we aimed to investigate the effects of Shaker exercise on aspiration and oral diet level in stroke survivors with dysphagia. METHODS Participants were randomly assigned to an experimental group (n = 16) or a control group (n = 16). Participants in the experimental group performed Shaker exercise and conventional dysphagia therapy, whereas those in the control group performed only conventional dysphagia therapy. All participants performed training 5 days a week for 4 weeks. Degree of aspiration was assessed using the Penetration-Aspiration Scale (PAS) based on videofluoroscopic swallowing study, while oral diet level was assessed using the Functional Oral Intake Scale (FOIS). RESULTS The experimental group showed greater improvement on both the PAS (p

Rip currents are strong water channels flowing away from the shoreline. They can occur on any shore with breaking waves. Rip currents play a significant role in changing the topography of shallow water regions by transporting large amounts of bed material offshore. Moreover, they pose a significant danger for people living in nearshore zones and surfers and cause hundreds of deaths annually worldwide. Therefore, rip current generation characteristics have been investigated to prevent casualties. In this study, a GPS drifter survey was chosen as the investigation method, however, a few drawbacks were discovered, such as low accuracy due to the GPS drifter becoming trapped in the surf zone. Therefore, drones and dyes were used to overcome the drawbacks of drifter methods. The results of dye tracking and the 3D wave-induced current numerical simulation were compared, the velocity and formation of the rip current were found to be relatively similar. With the technological advancements and invention of new survey equipment, the survey techniques also evolve, and this paper shows that the disadvantages of the GPS-based Lagrangian method can be overcome using a dye-mounted drone, which observes the rip current easily and accurately.

Institutions exhibit substantial heterogeneity in trading behavior. Although many studies consider their investment horizon or portfolio concentration in isolation, we propose a two-way investor classification that jointly accounts for both characteristics. Our conceptual framework provides an intuitive account of each institutional investor group’s trading and the ensuing impact on market price dynamics, offering fresh insights into seemingly mixed findings in the literature. Our results indicate that a short investment horizon and a high portfolio concentration are both proxies for an informational advantage. We also reveal substantial heterogeneity in the behavior of concentrated versus diversified institutions with similar investment horizons.

This article examines the effect of institutional investors’ investment horizons on firms’ innovation activities. We conjecture that the presence of long-term institutional investors mitigates managerial myopia, prompting firms to generate greater corporate innovation outputs. Using data on patents and patent citations for US firms, we find that institutions’ investment horizons are positively related to the number of patents and patent citations. We also document that long-term (short-term) institutional ownership is positively (negatively) related to the innovation outputs. This article makes an additional contribution to the corporate innovation literature by addressing the positive role of long-term institutional investors.

The stenotic geometry produces spatial and temporal regions such as high and low wall shear stress and flow separation. This disturbed blood flow in stenotic vessel can result in the further progress of atherogenesis. Therefore, the association between blood flow and geometrical factor need to be figured out by understanding the hemodynamic phenomena. The pulsatile flow features through a stenotic tube were investigated based on angiograms using a time-resolved particle image velocimetry (PIV) technique. A model of the tube core with stenosis was fabricated using a 3D printer, and the final tube model was fabricated with PDMS (polydimethylsiloxane). To prevent optical distortion, a mixture with glycerin and de-ionized water was used as the flow medium and a substitute for blood plasma. For PIV measurements, the concentration of fluorescence particles was controlled about 0.01 wt%. The flow rates were controlled using a circulating pump and silicon tubes from 1.6 to 3.7 mL/min. The pulsatile flow generates the local region of the maximum velocity at the post-stenosis and the shedding vortices move downstream over the time. The experiment indicates that such movements of vortices are quite different from the stagnant recirculation zone under the steady flow condition. With accumulating two-dimensional spatial flow fields obtained by phase averaging, the three-dimensional flow structure with the maximum velocity region was found to be a doughnut-shaped vortex ring.

This study empirically examines whether corporate social responsible firms exhibit more effective internal control over financial reporting. Specifically, we investigate whether socially responsible firms apply business practices to ensure financial transparency and accountability for their stakeholders. Using various measures of corporate social responsibility (CSR) and a battery of robust regression analysis over the period from 2004 to 2012, we find that CSR firms are more likely to have effective internal control under Section 404 of the Sarbanes-Oxley Act (SOX). Our results are robust to the propensity matching of firm characteristics, considering various measures of CSR, and adjusting for several endogenous problems.

The main objective of this research is to design and build a 200-kW ORC system with reduced size that could be installed in a steel processing plant where space is limited. The real-time operating characteristics of the ORC system are demonstrated with actual flue gases. First, an ORC system with R245fa refrigerant was developed for a heat source temperature of 140 °C. The evaporation and condensation pressures were 2,090 kPa and 220 kPa, respectively. The net power output was 235.7 kW with a thermal efficiency of 12.9%. Using an electric heat source, the design point performance of the system is experimentally demonstrated and shows a net power output of 177.4 kW with thermal efficiency of 9.6%. The turbine isentropic efficiency and generator efficiency were 68.1% and 98.5% at a rotational speed of 14,000 rpm. Next, the ORC system was implemented by designing a dedicated heat transfer loop for a steel processing plant using data measured from a chimney. The experimental net power output is 105.8 kW with a thermal efficiency of 8.6% when the plant is operated at the highest work load. The fluctuation of the flue gas temperature is successfully suppressed with a thermal storage tank installed in the heat transfer loop. A partial-load analysis was conducted and showed that the system has the highest performance with more than 165 kW of net power output. Economic analysis of such system showed that the right sized ORC system with always working parent plant had good economics with a payback period of 9 years.

Several countries suffer from rising sea levels which aggravate beach erosion and wave overtopping. Many Pacific island nations including Tuvalu are faced with the threat of disappearing as rising sea levels cause beach erosion. For this reason, countermeasure designs are needed to prevent this. It is difficult to build sturdy constructions on Pacific islands due to their locations far from developed countries which makes installation difficult. Moreover, Pacific island nations have low wave energies making soft techniques suitable as countermeasures. Eco-friendly designs that use the soft technique, and which also do not ruin the landscape, can be chosen as a design technique for these areas. Various economical and eco-friendly soft techniques using locally produced materials were applied in this study to protect against possible damage from erosion as well as overtopping. Hydraulic model tests were conducted to evaluate the effectiveness of these designs. In eco-friendly designs, locally produced sand and gravel nourishments and gravel bags using locally produced gravel were compared through hydraulic model tests. Gravel nourishments showed good results as a countermeasure when using the wave characteristics of Cyclone Ula, which has a 10-year return period; however, gravel dunes formed on the backshore which might spoil the aesthetics of the shore. The results of gravel bags along with sand nourishment showed a relatively good level of protection and additionally it can prevent gravel from moving around and spoiling the aesthetics of the shore.

Objective To examine the correlation between ultrasonographic trunk muscle parameters and balance scales in mild acute stroke patients.Methods A total of 55 stroke patients with hemiparesis and motor power grade ≥4 in the manual motor test were included. The Scale for the Assessment and Rating of Ataxia (SARA), Berg Balance Scale (BBS), Timed Up and Go Test (TUG), and Trunk Control Test (TCT) were used to evaluate patient balance function. Ultrasonographic parameters were measured on both non-paretic and paretic sides of the rectus abdominis, external oblique, internal oblique, transversus abdominis, and erector spinae muscles. Resting thickness and contraction thickness were measured in all muscles, and contractility and contractility ratio were calculated based on measured thicknesses. The differences between paretic and non-paretic muscle parameters, and the correlation between ultrasonographic parameters and balance scales were analyzed. Stroke patients were divided into two groups according to their fall risk. Ultrasonographic measurements between the two groups were compared.Results All muscles’ contraction thickness and contractility were significantly different between paretic and non-paretic sides (p

A simple and inexpensive measurement system is suggested to measure the temperature and velocity fields simultaneously at high temperature using thermographic phosphor tracer particles. A 385-nm UV–LED and only one high-speed camera with a CMOS sensor were used for the simultaneous measurement system. The dispersion of a confined oil jet with high temperature was investigated to validate the system. The instantaneous temperature and velocity fields were obtained when silicon oil at 200 °C was injected into a silicon oil chamber at 25 °C. The decay-slope method was used for the temperature field analysis, and the velocity field was obtained by a two-frame cross-correlation algorithm. The velocity of the injected silicon oil rapidly decreased because of the change in viscosity of the silicon oil with temperature. The selection of an appropriate interrogation window size is suggested to take the moving distance of temperature-sensitive particles into account for accurate temperature measurement.

The aims of this study are to visualize gas diffusion process between gas–liquid interface and measure a diffusion coefficient of dissolved oxygen in water by using a microscale UV-LED-induced phosphorescence method. The mass transfer between air and water was visualized qualitatively in a Y-shaped microchannel and the diffusion coefficient D L was measured quantitatively. Oxygen-sensitive phosphorescence dye (tris (2, 2′-bipyridine) ruthenium (II) chloride hexahydrate) and a 450 nm UV-LED were used for the optical measurement of a dissolved oxygen concentration (DOC) field. In-situ pixel-by-pixel calibration was carried out to obtain Stern–Volmer constant and phosphorescent intensity was converted to DOC field with a spatial resolution of 0.625 μm/pixel. Instantaneous dissolved oxygen concentration field and diffusion coefficient D L were successfully measured and compared to the theoretical prediction based on the one-dimensional Fick’s law. It was confirmed that the experimental results were in good agreement with the numerical prediction.

In this paper, we examine how firm financial conditions and governance characteristics affect reverse mergers’ survival. Using a sample of reverse mergers that took place in the United States during the 1997–2009 period, we find that firms with better corporate governance are more likely to survive after a reverse merger. In particular, CEO ownership, staggered board dummy, and venture dummy have a positive association with reverse merger survival. We also show a concave relation between the average board tenure and the probability of reverse merger survival. In contrast, most of the firm characteristic variables have an insignificant relationship with reverse merger survival. Our results suggest that the survivability of reverse mergers relies more on the presumed value-enhancing governance characteristics than on the financial conditions of the merging firms.

Kim, H.D.; Aoki,S.; Kim, K.H.; Kim, J.; Shin, B., and Lee, K., 2020. Bathymetric survey for seabed topography using multibeam echo counder in Wando, Korea. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 527–531. Coconut Creek (Florida), ISSN 0749-0208.Bathymetric survey measures the water depth of the ocean floors accurately. This survey helps produce a nautical chart which is used in numerical simulations, constructions, and more, as well as this project itself. This particular study was conducted to measure the water depth and map the ocean floor of Wando, Korea. With the help of various types of equipment, including multibeam echo sounder, differential GPS (DGPS), motion sensor, gyro compass, and sound velocimeter, bathymetric survey was made possible. Multibeam echo sounder was attached to the boat, emitting a total of 256 beams from a point centered directly below the boat. Water depth data was acquired from the underwater sound velocity using the return time of the beam. DGPS calculated the error value by comparing the position data of the control point at the base station where the position is already known via the Korea Hydrographic and Oceanographic Agency and where the position value is measured by using the receiver of the GPS. Throughout the survey, abnormal bodies were found even after the quality control filtering. These objects were as such classified through further detailed investigation.

Shim, K.T.; Kim, K.H.; Kim, H.D.; and Kwak, K.S., 2020. Analysis on sediment transport system in the East coast of Korea. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 643–648. Coconut Creek (Florida), ISSN 0749-0208.In an area comprising a long and a monotonous coastline such as that observed along the east coast of Korea, erosion and accretion can occur repeatedly due to seasonal influences; this leads to the formation of an equilibrium for the sediment budget. However, the construction of artificial structures has caused changes in the sediment budget, which has led to unidirectional sediment transport and excessive erosion and accretion. Recently, there has been an increase in the frequency of appearance of high wave groups that are observed for long periods due to a rise in the sea level and the emerging abnormal climate. This has caused large-scale morphological change and is the major factor that accelerates beach erosion. This study monitors a target area wherein a sediment transport was observed to actively occur; this was achieved by using a beach stabilization measure. The variations in the beach profile and the ratio of the sandy beach budget were predicted using the results obtained. In addition, the sediment transport system of the east coast of Korea was examined through comparison with empirical formulas by classifying the erosive and sedimentary beaches. This study also presents the indicators that will govern the topography of Korea in the future.

The behavioral finance literature attributes failed M&As to CEO overconfidence. We investigate the source of CEO overconfidence that leads to failed M&As. Among various determinants of CEO overconfidence, we propose that power-led CEO overconfidence delivers undesirable consequences in corporate investments. Using CEO-level data, we find that CEO power increases the probability of a CEO being overconfident. We also show that power-led overconfident CEOs tend to complete more deals regardless of economic circumstances, do stock acquisitions, and make diversifying acquisitions, relative to non-overconfident CEOs. The results suggest that the findings of previous studies on M&As by overconfident CEOs could be driven by power-led overconfident CEOs.

Functional graded Ti-Al-Si-N-O nanocomposite films were deposited onto WC-Co substrate by a filtered arc ion plating system using TiAl and TiSi composite targets under N₂/Ar atmosphere. XRD and XPS analyses revealed that the synthesized Ti-Al-Si-N-O films were nanocomposite consisting of nanosized (Ti, Al, Si)N crystallites embedded in an amorphous Si₃N₄/SiO₂ matrix. The hardness of the Ti-Al-Si-N-O films exhibited the maximum hardness values of ~47 GPa at a Si content of ~5.63 at.% due to the microstructural change to a nanocomposite as well as the solid-solution hardening. Besides, Ti-Al-Si-N-O film with Si content of around 5.63 at.% also showed perfect adhesive strength value of 105.3 N. These excellent mechanical properties of Ti-Al-Si-N-O films could be help to improve the performance of machining tools and cutting tools with application of the film. A comparative study on microstructural characteristics among Ti-Al-Si-N-O films with various Si contents is reported in this paper.

This study investigated the time taken for upper extremity spasticity to develop and its regional difference after first-ever stroke onset in a nationwide multicenter study in South Korea. The retrospective observational study included 861 individuals with post-stroke spasticity in the upper limbs. Spasticity in the upper extremity joints was defined as a modified Ashworth Scale score ≥1. The median time to develop upper limb spasticity after stroke onset was 34 days. 12% of post-stroke spasticity cases developed between 2 months and 3 months and 13% developed after 3 months from onset. At the time of diagnosis of spasticity, most patients showed only a slight increase in muscle tone, which was observed most frequently in the elbow, followed by the wrist, and fingers. Younger stroke survivors were more spastic, and the severity of spasticity increased with time. Approximately half of the patients with post-stroke spasticity developed spasticity during the first month. However, post-stroke spasticity can develop more than 3 months after stroke onset. Therefore, it is important to assess spasticity, even in the chronic state.

Three-dimensional (3D) curved wall jets are a significant topic in various applications related to local heat and mass transfer. This study investigates the effects of the impinging angle and Reynolds number with a fixed distance from the nozzle to the surface of a cylinder. The particle image velocimetry (PIV) method was used to measure the mean streamwise velocity profiles, which were normalized by the maximum velocity along the centerline of the impinging jet onto the cylinder. After the impingement of the circular jet, a 3D curved wall jet develops on the cylinder surface due to the Coanda effect. At a given Reynolds number, the initial momentum of the wall jet increases, and flow separation occurs further downstream than in normal impingement as the impinging angle increases. At a given impinging angle, flow separation is delayed with increasing Reynolds number. A self-preserving wall jet profile was not attained in the 3D curved wall jet. The turbulence intensity and the Reynolds shear stress were obtained to analyze the turbulence characteristics. The radial turbulence intensity showed similar tendencies to a two-dimensional (2D) curved wall jet, but the streamwise turbulence intensity was dissimilar. The Reynolds shear stress decreases downstream of the cylinder wall due to the decreased velocity and centrifugal force.

The amount and quality of waste heat from a gas engine which is modified from an automobile gasoline engine is analyzed. Exhaust temperature is 573.8 ℃ and engine cooling water exit temperature is 85.7 ℃. The amount of waste heat of engine cooling water is double compared to that of exhaust gas. Organic Rankine cycle (ORC) system is designed for two different waste heat source of engine cooling water and en- gine exhaust and is thermodynamically analyzed.

>> In a gas engine, the exhaust and the engine cooling water are generated. The engine cooling water temperature is 100 ℃ and the exhaust temperature is 500 ℃. The amount of heat of engine cooling water is43 kW and the amount of heat of exhaust is 21 kW. Eight different hybrid organic Rankine cycle (ORC) systemconfigurations which considering different amount and temperature of waste heat are proposed for two gas enginetri-generation system and are thermodynamically analyzed. Simple system which concentrating two different wasteheat on relatively low temperature engine cooling water shows highest thermal efficiency of 7.84% with pressureratio of 3.67 and shaft power of 5.17 kW. Key words : Gas engine(가스 엔진), Engine exhaust(엔진 배기), Organic Rankine cycle(유기랭킨사이클), Hybridsystem(하이브리드 시스템), Thermodynamic analysis(열역학적 분석) † Corresponding author : kckim@pusan.ac.kr Received : 2015.01.02 in revised form 2015.01.24 Accepted: 2015.02.28Copyright ⓒ 2015 KHNES Nomenclature h : enthalpy (kJ/kg)η : efficiency

This study examined the photo-bleaching characteristics of oxygen-sensitive particles (OSPs) using a high-speed imaging technique. The OSPs were fabricated by a dispersion polymerization method and dipping method using porous micro spheres. Two representative oxygen indicator molecules, platinum octaethyl porphyrin (PtOEP) and platinum (II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP), were used to make four kinds of OSPs. A ultraviolet light emitting diode (UV-LED, M385L2, THORLABs) with a wavelength of 383 nm, a microscope with a 20X objective lens and a high-speed camera were adopted for the high-speed imaging of OSPs. The photo-bleaching characteristics of the OSPs were compared according to the time and power of UV-LED. The dispersion-polymerized OSPs had higher photostability than the porous OSPs, and the PtTFPP-embedded porous OSPs were more stable than the PtOEP-embedded porous OSPs due to the molecular structural characteristics. The dispersion-polymerized OSPs incorporated with PtOEP were more stable than the dispersion-polymerized OSPs incorporated with PtTFPP.

In this study, a simple and fast data analysis method using the decay-slope of phosphorescence was suggested for the phosphor thermometry to obtain instantaneous temperature field in high and a wide range of temperature. Mg 4 FGeO 6 :Mn was used as TP, and pulsed UV-LED and a CMOS high speed camera with 4000 frames per second were used for the phosphor thermometry. A data processing procedure for pixel by pixel in-situ calibration and temperature measurement was also suggested. To reduce data processing time and uncertainty, the interrogation window concept was introduced. Post-processing of the calibration and experimental data was analyzed using MATLAB, and a number of concepts that could reduce the computation time remarkably were suggested. Comparison of performances in both the decay-slope analysis and the lifetime analysis was made with the same number of data. As a result, the decay-slope method improved computation time more than 23 times faster than that of the lifetime analysis and the calibration accuracy was similar for both methods.

Objective To demonstrate the utility of Scale for the Assessment and Rating of Ataxia (SARA) for evaluation of posterior circulation-related features in patients with mild stroke. Methods Forty-five subjects, diagnosed with acute infarction in the cerebellum, basis pontis, thalamus, corona radiata, posterior limb of internal capsule, and their National Institutes of Health Stroke Scale (NIHSS) scores ≤5 were enrolled. SARA scores were graded by the cut-off value of severity in dependency of activities of daily living (ADL). SARA, Berg Balance Scale (BBS), Timed Up-and-Go (TUG), and Trunk Control Test (TCT) were correlated in regression analysis with the modified Rankin Scale (mRS) at discharge. Correlation between SARA and other tools was analyzed. Patients were divided based on mRS at admission (group A, mRS 0–2; group B, mRS 3–5). Scores between the two groups were compared. Results Among the subjects, 48.9% (22/45) scored above 5.5 on SARA, and even 11.1% (5/45) scored higher than 14.25, which is the cut-off value of ‘severe dependency’ in ADL. SARA showed significant value for prediction of mRS at discharge. SARA was correlated with BBS (r=-0.946, p

Spatial and temporal variations of the hemodynamic features occur under pulsatile conditions in complex vessel geometry. Wall shear stress affected by the disturbed flow can result in endothelial cell dysfunction, which leads to atherogenesis and thrombosis. Therefore, detailed understanding of the hemodynamic characteristics in a curved stenosed channel is highly important when examining the pathological effects of hemodynamic phenomena on the progression of atherosclerosis. The present study measures the velocity fields of pulsatile flows with three different Reynolds numbers in 3D curved vessel models with stenosis using time-resolved particle image velocimetry (PIV). Three different models were cast in PDMS polymer using models made by a 3D printer with different bend angles of 0°, 10°, and 20° between the longitudinal axes at the upstream and downstream of the stenosis. To investigate the 3D flow structures, a stack of 2D velocity fields was obtained by adjusting the position of the laser sheet along the Z-direction. The structures of flow fields in the stenosed models were analyzed using the distribution of the shearing strain as well as the skewness and full width at half maximum of the velocity profile. To support experiment results, distributions of pressure and 3D vortex in the curved stenosed channels were estimated by conducting the numerical simulation. These results indicate that the curvature of the tube considerably influences the skewness of the flow, and the shear stress is intensified near the outer curvature wall due to centrifugal force. The results would be helpful in understanding the effects of geometrical factors on plaque rupture and severe cardiovascular diseases.

In this paper, we examine whether the presence of ex-military board directors affects firms’ financial policies and ethical behavior in Korea, a country where the military has a unique historical role in society. Despite prolonged exposure to military rule during their formative years, firms with ex-military-officer CEOs and inside directors are substantially less likely to commit corporate fraud. Moreover, the positive association between Chaebol business groups and fraud is significantly weakened in the presence of ex-military directors. These managers and insiders also adopt more conservative managerial policies in normal times but take more risks during crisis periods. However, when these directors are appointed primarily for external networking purposes, their presence has little effect on a firm’s corporate policies or ethical behavior. Thus, a director with exposure to military values does appear to enhance corporate ethics, but only when he holds an appropriate position to do so.

Due to the increase in population and the standard of living along with rapid industrialization, various kinds of water demands have been increasing resulting high pollutant emissions. Moreover, the level of pollution in regards to the water quality of oceans, lagoons, and rivers has been aggravated. In particular, lagoons across the globe are suffering from the use of fertilizers, manual wastes and dead remains. A lack of dissolved oxygen (DO) has been a problem for the lagoon water quality. Many living creatures in the lagoon have become prone to death and their dead remains further aggravate the water quality. Dredging the bottom of lagoon to remove various wastes, vegetation inside the lagoon for self-purification and employing micro bubble machines to increase DO are methods to alleviate the problem. Alternative and additional solutions may be applied depend on the condition of the lagoon. For most lagoons are comprised of oxygen-deficient water mass, a micro bubble machine is particularly efficient for its micro-aeration in amplifying DO. Regular aeration method may accompany inefficiency in increasing the level of DO in the lower boundary of water since the airdrops easily rise to the surface. Micro bubble system is employed for less oxygen rise to the surface over regular aeration. In this study, Micro bubble device is applied to Youngrang Lagoon in the east coast of Korea to investigate the efficiency of micro bubble technique. DO alleviate operation shows significant changes in DO level, yet it requires excessively high costs. To eliminate the shortcomings of the operation, renewable energy such as solar and wind energy are under consideration for valuable alternatives.

The spatial structures of a submerged jet interacting with a free surface were examined experimentally. The time-resolved PIV technique was used for the quantitative measurements. Two Reynolds numbers (1920, 3480) were examined for a configuration, in which the depth of the jet beneath the free surface was fixed to H = 2D. The dynamics of the flow structures were examined further using the space–time proper orthogonal decomposition (POD) analysis technique. Some common characteristics were found in both jet flows, which are believed to be the general features of the free-surface jet flows. On the other hand, the dynamic characteristics of the large-scale turbulent motions differed significantly with respect to the Reynolds number. In the low Reynolds number case, three dominant dynamic structures were found: flapping motion of the jet, very large scale vortical structure interacting with the free surface at the right side, and the transverse stretching of large scale structure due to the presence of free surface. The reconstructed fluctuating velocity fields and the swirling strength contours demonstrated that the very large scale structures began to move downward at about 10D downstream the initial interaction. In the high Reynolds number case, the first two dominant spatial modes showed the momentum exchange process between the jet flow and the free surface. The third mode displayed a vortex just below the free surface at the left side and the fourth mode showed the elongated vortex structures. The scale of vortical structures was much smaller in the high Reynolds number case than that in the low Reynolds case, and the downward motion of large scale structures was not found in the high Reynolds number case.

This study examined the transient behavior of liquid films and the flow of inner gas. Olive oil particles were inserted into a soap bubble through a Laskin nozzle for visualization, and the inner gas flow fields were measured by time-resolved particle image velocimetry. A pulse laser was used for contactless rupturing of the soap bubble. The transient behavior of the liquid film after the soap bubble ruptured was captured using a high-speed camera at 3,600 frames per second. After rupturing the soap bubble, the inner gas flowed out to the outside through the crack. This is called the primary flow. The removal velocity of the upper liquid film was faster than that of the bottom liquid film. The Kelvin–Helmholtz vortex was generated at the upper and bottom boundaries of the liquid film. A series of Kelvin–Helmholtz vortices, which arise in shear flow along a contact discontinuity, were formed around the bubble sphere. Secondary flow was generated due to a change in momentum after impinging the soap film to a point, and was faster than primary flow.

Objective To compare transverse abdominis (TrA) contractility in stroke patients with hemiparesis and healthy adults using musculoskeletal ultrasonography. Methods Forty-seven stroke patients with hemiparesis and 25 age-matched healthy control subjects participated in this study. Stroke patients were divided into three groups on the basis of their degree of ambulation. Group A consisted of 9 patients with wheelchair ambulation, group B of 23 patients with assisted ambulation, and group C of 15 patients with independent ambulation. Inter-rater reliability regarding ultrasonographic measurement of abdominal muscle thickness in the control group was assessed by two examiners. The TrA contraction ratio (TrA contracted thickness/TrA resting thickness) was measured during abdominal drawing-in maneuver and was compared between the patients and the control group and between the ambulation groups. Results The inter-rater reliability ranged from 0.900 to 0.947. The TrA contraction ratio was higher in the non-paretic side than in the paretic side (1.40±0.62 vs. 1.14±0.35, p

Lee, Y.B.; Kim, K.H; Kim, H.D; Kim, J., Kwak, K., and Park, T., 2019. High wave predictive numerical simulation for the wave alarm system. In: Lee, J.L.; Yoon, J.-S.; Cho, W.C.; Muin, M., and Lee, J. (eds.), The 3rd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 91, pp. 91-95. Coconut Creek (Florida), ISSN 0749-0208.In recent times, coastal damage has been on the increase due to rising sea levels as a result of global warming and the increasing frequency of high waves as a result of climate change. High swells and waves directly invading the coastline propagate more energy onto the shoreline than preexisting waves, causing physical damages such as coastal erosion as well as human casualties. However, an alarm system that can predict high waves by analyzing weather forecasts and transmit the information to a user in real time does not yet exist. Such a technology is necessary to prevent damage and human loss to ever increasing high swells and waves. This research aims to successfully predict high waves by using real time weather data in its simulations to detect potential danger in a user's location, as part of the larger research for the development of a high wave alarm system technology.

When erosion occurs, sandy beach cannot maintain the sufficient sand width and the foreshore slope becomes steeper by the frequent erosion effect. As a result, the beach is trapped in a vicious circle of becoming vulnerable by the incident waves. In order to repair or protect the erosive beach, beach nourishment can be used as a countermeasure while minimizing the environmental impacts. However, beach nourishment is not a permanent solution and requires periodic renourishment after several years. To alleviate such problem, minimizing the period of renourishment must be an economical alternative. In that respect, selecting the optimum grain size of the sand for the beach nourishment is very important. Generally, larger grain sized sand is more resistant to the erosion, thus extending the period of renourishment. In addition to selecting the optimum grain size of the sand nourishment, determining the durability as well as maintaining the familiarity of the users of the native sand should be considered.

The effectiveness of structures placed on the foreshore of a sand beach and a berm was tested and confirmed to reduce wave overtopping and sand overwash, expanding upon the previous comparison test conducted by Kim et al. (2016) with using sand and two different sizes of stones shown in Table 1. Test contains two test series of a rock seawall (Series R) and a dune with a buried seawall (Series B) on the foreshore as shown initial of the two structures in Figure 1 which reduced both wave overtopping and sand overwash even after its deformation. Damage was inflicted upon these two structures which seems to be caused by either stone displacement or structure settlement. To find out which was the case, detailed analysis has been conducted, along with an application of the cross-shore numerical model CSHORE (Kobayashi 2016) for the purpose of simulating sand and stone interactions in the swash zone on the sand beach.

KeyWords: Organic Rankine Cycle(유기랭킨사이클), Scroll Expander(스크롤팽창기), Thermal Efficiency(열효율), Isentropic Efficiency(등엔트로피효율)초록: 본연구에서는소형저온유기랭킨사이클시스템의작동특성을파악하기위하여R-245fa를작동유체로사용한소형ORC 발전시스템을설계및제작하였고, 다양한저온의열원온도에대한실험적연구를수행하였다. 저온열원을모사하기위하여최고150 °C의물을공급할수있는110 kW급의전기저항히터를제작하였으며, 컨트롤러를통해서다양한열원온도및유량조건에대한실험이가능하도록구성하였다. 또한, 상용공기용스크롤압축기를이용하여팽창기로개조하고동력계및동기식모터와직접연결하였다. 로드뱅크및PI 제어방식을사용하여팽창기의회전속도에따른동일열원온도조건에대한실험을각각수행하였으며, 소형ORC 시스템의성능에영향을미치는다양한인자들에 대하여분석하고논의하였다.Abstract: Experiments were conducted to determine the operating characteristics of a small-scale ORC (organicRankine cycle) system for various low-temperature heat sources. A small-scale ORC power generation systemadopting R-245fa as a working fluid was designed and manufactured. Hot water was used as the heat source,and the temperature was controlled using 110-kW electric resistance heaters that provided temperatures of upto 150 °C. An open-drive oil-free scroll expander directly connected to a synchronous generator was installedin the ORC unit. Experiments were conducted by varying the rotational speed of the expander under thesame heat source temperature conditions. The factors that influence the performance of the small-scale ORCsystem were analyzed and discussed.

Recently, with the sudden changes in the security environment, expectations towards the police and fear towards safety are increasing. Thus, the local community police operation, which creates a mutually cooperative relationship between the police and local residents, is coming to the fore as the paradigm of the nationwide police operation. The police operation in Korea has also gone through change, and as part of the local community police operation, Korea has implemented a community police system since 2003. Recently, the system has been going through change in that the operations are centralizing around not only prevention of crime including the safe city program, protection of multicultural families, response to foreign crime, protection of the socially disadvantaged but also life security of the citizens. Along these lines, this study seeks to examine conditions of the three elements of local community police operation - Strategic Oriented Policing (SOP), Neighborhood Oriented Policing (NOP), Problem Oriented Policing (POP) - and policy suggestions accordingly.

This paper describes aerodynamic characteristics of an Archimedes spiral wind turbine with variousangles of attack. The range of angles was controlled from - 30 o (clockwise) to + 30 (clockwise). The rotatingspeed of wind turbine at the same angle of attack in both directions was different. The reason why the-maximum rotational speed was observed at 15 o in clockwise direction can be explained based on angularmomentum conservation. Quantitative flow visualization around Archimedes wind turbine blade was carriedout between -15 o (clockwise) and +15 (counter clockwise) using high resolution PIV method. The relation-ship between drag force and rotating speeds was discussed. From these results, optimum design on yawingsystem of Archimedes spiral wind turbine may provide high efficiency on small wind power system.Key Words:Spiral Wind Power Generation(스파이럴형풍력발전), Archimedes Spiral(아르키메데스나선 ),Aerodynamics Characteristics(공력특성), PIV measurement(PIV측정), Angle of Attack(받음각) 기호설명 θ: Angle of Attack [