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Trends of large-scale ships have seen propulsion shaft and propeller sizes increase. This has enabled shafts to have greater stiffness, yet has caused flexibility to lessen and induce bearing failure at the aft stern tube bearing. In general, shaft alignment is calculated and evaluated in accordance with classification societies’ rule requirements. Especially, positioning reaction support and stiffness of aft stern tube bearing are based on the practical experience of shaft alignment. Therefore, in this study, to evaluate the feasibility of the reaction force supporting position and stiffness of the aft stern tube bearing as recommended by classification societies in shaft alignment, theoretical reaction force supporting positions for various ship propulsion shafting systems were examined and the differences were evaluated. The reaction force supporting position of the aft stern tube bearing provided by classification societies was evaluated and it was found that a propeller shaft diameter less than 600 mm is within the provided range. However, in the evaluated shafting system, a propeller shaft diameter of more than 600 mm tends to cause the ship to move to the forward side due to increased shaft stiffness.

In recently constructed vessels, minimization of engine room volume is required to maximize the volume of cargo to be shipped. Therefore, the main engine and the stern bulkhead mounted on the ship are installed as far as possible in the aftward direction. As a result, the length of the propeller shaft is reduced, along with the stern tube bearing span used to support it. In this case, the shaft flexibility is reduced, the reaction influence number is increased, and the point load of each bearing is easily influenced by change in displacement. Because the point load of each bearing is susceptible to hull deformation and thermal expansion, it is difficult to adjust the shaft arrangement and the bearing load change after large adjustment of the shaft arrangement. Therefore, in the past, the bearing was arranged to support the propeller shaft with two forward and afterward stern tube bearings. However, when the main engine and the stern bulkhead are installed as far aftward as possible to minimize the volume of the engine room, it is necessary to provide shaft flexibility by removing the forward stern tube bearing. As a result, the resonance revolution of the propeller blades during whirling vibration of the propulsion shafting system falls within the range of normal operating revolutions. This means that abnormal wear of the stern tube bearing, damage to the stern tube sealing device, and hull structure vibration may occur due to the whirling vibration. In this paper, the characteristics of shafting alignment and whirling vibration of a ship supporting a propeller shaft with double and single stern tube bearings are compared. Moreover, the changes in shaft flexibility and the characteristics of the whirling vibration of a corresponding shafting system in a 50 K-DWT petroleum product tanker were explored by applying a single stern tube bearing. In addition, the shafting alignment and whirling vibration are determined according to the installation position of the intermediate shaft bearing. A method is suggested for selecting the optimal shafting arrangement by which to secure the shaft flexibility of a ship to which a single stern tube bearing is applied, and to avoid resonance from the whirling vibration.

The problem of environmental pollution from CO2 emissions is drawing worldwide attention. With this trend, within the automotive industry, development of lightweight parts and application examples are increasing to react to environmental regulations and to obtain better mileage. Furthermore, with the demands of the time to cut energy consumption and to protect the environment, recycling aluminum, which is being widely used for daily necessities as well as for industrial purposes, is important. Recycling aluminum can be critical in environmental protection, resource saving, and both pollution and waste prevention. The demand in aluminum alloy is increasing since it provides better intensity, lower density and superior corrosion resistance when compared with steels. In particular, the Al-Si-Cu Aluminum alloy, which possesses outstanding castability and mechanical properties, is extensively utilized for automotive parts as a cylinder head, among others. Thus, this study will use test pieces melting and casting commercial A319 ingot and other pieces remelting cutting chips which are discharged and processed from automotive parts manufactured with A319 alloy to investigate changes in microstructure, hardness and tensile tests. Through these processes, this study aims to research the possibilities of remelted A319 alloy to be utilized as a casting material based on characteristic comparison of the material.

As part of recent efforts to reduce emissions and get significant fuel savings with ships, ultra-long stroke engines, (hereafter G-type engines), are now commonly used in eco-ships. The best feature of G-type engines is their ability to generate greater power at lower speeds than previous designs to get higher propulsion efficiency. In some recent cases, however, operators of eco-ships have experienced problems related to being unable to pass quickly enough through their critical speed within the overall range of operating speeds. In this study, the characteristics of the torsional vibration in a propulsion shafting system equipped with a fuel saving ultra-long stroke engine were reviewed. This review included the technology developed for improvement of the acceleration capacity in low load ranges in eco-ships. Then a proper examination was conducted of methods for alternative design of propulsion shafting systems to cope with the engine acceleration problem in the barred speed range.

To cope with the long term recession in the shipping industry due to oversupply of ships and high oil prices and due to reinforcement of environmental regulations to reduce greenhouse gas emission from ships, large container vessels built recently have ultra-long stroke engines with high propulsion efficiency. For these, de-rated engine and tuning technologies are used to reduce fuel oil consumption. However, previously built vessels were optimized for high ship speed. In these case, lowering ship speed to reduce ship operating cost does not provide similar benefits. Therefore, engine manufacturers have developed a turbocharger cut-out system to reduce fuel oil consumption at low speed. This has the advantage of reducing fuel consumption at low speeds, but also has the characteristic of producing higher torsional exciting force than is typical in existing engines for low load ranges. In this paper, the performance and dynamic characteristics of a marine diesel engine were reviewed after applying a turbocharger cut-out system. Then the effects on the engine body vibration and the torsional vibration were examined for a corresponding propulsion shafting system in a Panamax container-vessel equipped with a turbocharger cut-out system optimized for slow steaming. As a result, the torsional vibratory stress in shafts was increased. This had a larger effect on the X-mode shape of the engine body vibration and on the upper structure vibration, when one of three turbochargers was cut out.

Surface chemistry is a significant field of research, especially for the preparation of organic-inorganic hybrid materials in which nearly every atom is anchored at the interface. Herein we report on the functional binding agents (FBAs), Mg(OH)2 or Co(OH)2-Mg(OH)2-Co(OH)(NO3), as efficient tools for functionalising surfaces, whereby the morphology and growth of the organic-inorganic coating can be varied by varying the interfacial composition to achieve improved functionality. To demonstrate the potential of this strategy, we combine plasma electrolytic oxidation (PEO) and a two-step dip chemical coating (DCC) technique to deliver multi-layered constructions of several chemical compositions comprising inorganic and organic components. A novel single layer of FBAs is fabricated on the rough inorganic coating through chemical treatment via DCC, transforming it into a binding site for primary clusters of 2-mercaptobenzimidazole (MBI) molecules. Thus, FBAs form coordination complexes with organic molecules, which grow on FBA surfaces. Finally, electrochemical measurements reveal that the self-assembly of organic-inorganic hybrid heterostructures appreciably suppresses metal oxidation and oxygen reduction, due to a synergistic effect arising from the combination of FBAs with organic and inorganic coatings.

Dynamic compressive properties of a Boryeong shale were evaluated by using a split Hopkinson pressure bar, and were compared with those of a Hwangdeung granite which is a typical hard rock. The results indicated that the dynamic compressive loading reduced the resistance to fracture. The dynamic compressive strength was lower in the shale than in the granite, and was raised with increasing strain rate by microcracking effect as well as strain rate strengthening effect. Since the number of microcracked fragments increased with increasing strain rate in the shale having laminated weakness planes, the shale showed the better fragmentation performance than the granite at high strain rates. The effect of transversely isotropic plane on compressive strength decreased with increasing strain rate, which was desirable for increasing the fragmentation performance. Thus, the shale can be more reliably applied to industrial areas requiring good fragmentation performance as the striking speed of drilling or hydraulic fracturing machines increased. The present dynamic compressive test effectively evaluated the fragmentation performance as well as compressive strength and strain energy density by controlling the air pressure, and provided an important idea on which rock was more readily fragmented under dynamically processing conditions such as high-speed drilling and blasting.

Highly chemical stable and antibacterial materials are desirable for bone reconstruction and packaging applications. Crosslinked polymer-inorganic materials have attracted significant attention in this respect owing to their low cost, simplicity and excellent mechanical properties. Up to this work, it remains challenging to fabricate hybrid organic-inorganic films with controlled electrochemical, photocorrosion, and antibacterial performance that are stable in the aggressive solutions and solvents. In this protocol paper, we report a new approach to designing crosslinked polymer-inorganic films with enhanced corrosion protection and antibacterial performance by manipulating the amount of citric acid (CA) and polyvinyl alcohol (PVA) in the hydrogen film PxCy (x = 10, 8, 6.5, 5, 2 g; y = 0, 2, 3.5, 5, 8 g). Ultrathin PxCy films are fabricated in situ by interfacial crosslinking process on the porous inorganic surface (IC) synthesized via straightforward plasma electrolysis (PE). Enhanced electrochemical, photocorrosion and potential antibacterial performance for IC-PxCy film is achieved by using contorted crosslinking agent, CA, for the interfacial crosslinking process. The electrochemical performance is enhanced remarkably in the order of IC-P6.5C3.5, IC-P5C5, IC-P10C0, IC, and IC-P2C8, which account for the synergistic integration of the IC and PxCy as well as degree of crosslinking between PVA and CA. In addition, the results indicate that IC-P6.5C3.5, IC-P5C5 and IC-P2C8 have outstanding antibacterial activity.

Plasma electrolytic oxidation and dip chemical coating as fabrication techniques are performed in ambient temperature and pressure, giving a competitive-edge in the commercial applicability. Thus, we proposed new compositions of flower-like hybrid materials, MgO-TiO2-HQ(8-hydroxyquinoline), MgO-TiO2-HQ-APY(2-aminopyridine) and MgO-TiO2-HQ-APH(2-aminophenol), as photocatalysis with high corrosion resistance via a combination of plasma electrolytic oxidation and dip chemical coating in which 8-HQ, 2-APY, and 2-APH were used as the organic components. TiO2-HQ-APY and MgO-TiO2-HQ-APH exhibited improved simultaneous electrochemical and photocatalytic performance on photodecomposition of methylene blue (MB) in an aqueous solution in the presence of ultraviolet-visible irradiation comparing to that of MgO-TiO2-HQ. The synergistic effects of organic components anchored on TiO2 and MgO containing inorganic layer were the main source for enhanced anticorrosion resistance. The MgO-TiO2-HQ and MgO-TiO2-HQ-APH could be recovered simply by a magnet and reused several times with no significant diminution in high stability photocatalytic performance during catalytic oxidation. The work indicated that synergistic effects of aromatic heterocycles on TiO2 and MgO containing inorganic layer played key role in enhancing photocatalytic activity and electrochemical behavior. To support the experimental section, quantum chemical parameters such as highest occupied molecular orbital energy (EHOMO), lowest unoccupied molecular orbital energy (ELOMO), and gap energy (ΔE) were calculated using density functional theory.

Transition metal doped-crosslinked polymers have attracted noteworthy attention in this respect due to their economical, simplicity and durability properties. So far, it remains demanding to fabricate transition metal doped-crosslinked polymer-inorganic films with controlled photoelectrochemical performance that were stable in the aggressive solutions. Here, we report a new strategy to preparing transition metal doped-crosslinked polymer-inorganic layers with improved photoelectrochemical activity by manipulating the types of metal ions (Fe(III) and Co(II)) in the presence of polyvinyl alcohol (PVA) and ethylenediaminetetraacetic acid (EDTA), as crosslinking agents, in the hydrogen film “PEM” (P: PVA; E:EDTA; M: Fe(III)/Co(III)). PEM is prepared by interfacial crosslinking and then complexing process via static chemical conversion (SCC) on the inorganic layer (IL) surface fabricated via plasma electrolysis (PE). The photoelectrochemical performance is improved significantly in the order of IL-PEFe, IL-PECo, and IL-PEFe*Co, which may be due to transition metal ions and crosslinked polymers.

In the present work, microstructure optimization strategy driven by differential speed rolling (DSR) deformation followed by annealing was used to enhance strength and ductility of low-carbon steel (LCS). In this regard, LCS samples were deformed by DSR at a roll-speed ratio and total thickness reduction of 4:1 and 75%, respectively, and the DSR-deformed samples were then annealed at various conditions. The results showed that the sample deformed by DSR and annealed at 773 K for 6 h exhibited a combination of improved strength and good ductility.

Adapters are a component of the output system in the internally geared hub for a bicycle. Originally, adapter parts were produced by a machining process with low productivity and material usage rate. In this study, the metal powder injection molding (MIM) process has been applied as an alternative manufacturing method to the machining process. Microstructure analysis and mechanical property testing has been conducted in order to select the material for the adapter with changes in the nickel content. The geometrical precision of the adapter is measured by using three-dimensional scanner with various mixing ratios of the powder and the binder. The developed alternative process for the adapter results in increased productivity and material usage rate. Previously, this process was only used for small parts less than 10 mm in diameter. With this development, the MIM process may be used more widely than before.

We report the use of self-assembled graphene oxides (GO)/8-hydroxyquinoline (8-Hq) /inorganic coating (IC) hybrid materials as protective materials that inhibits corrosion of underlying metals. We present the fabrication of a multilayer coating, GO/8-Hq/IC, combining graphene oxide and flowerlike organic-inorganic materials using a defective coating as the inorganic compounds and graphene oxides with 8-hydroxyquinoline as the organic compounds. The 8-Hq molecules form coordination complexes with metal ions (Mg (II) and Al (III)) from porous inorganic coating layer, and these complexes become knot sites for molecular self-assembly of 8-Hq and then GO particles. Physical adsorption between the molecular self-assembly of 8-Hq and GO particles leads to the growth of micrometer-sized particles that have nanoscale features. Finally, the extraordinary electrochemical stability was enhanced in the order GO/8-Hq/IC, 8-Hq/IC, and IC, which was discussed on the basis of polarization interpretation. The findings indicate that AZ31 Mg coated with the self-assembled GO/8-Hq/IC materials grown via plasma electrolytic oxidation and dip-chemical coating are corroded several times slower in aggressive solution as compared to corrosion rate of bare magnesium.

1) The purpose of this study was to assess the influence of the duration of smartphone usage on cervical and lumbar spine flexion angles and reposition error in the cervical spine. The study included 18 healthy smartphone users (7 males and 11 females). We measured the kinematics of the upper and lower cervical and lumbar spine flexion angles and the reposition error of the upper and lower cervical spine after 3 s and 300 s smartphone use in sitting. A paired t-test was used to compare the effects of the duration of smartphone usage on the kinematics of cervical and lumbar spine flexion angles and reposition error. The flexion angles of the lower cervical and lumbar spine and the reposition error in the upper and lower cervical spine were significantly increased after 300 s smartphone of use (p .05). These findings suggest that prolonged use of smartphones can induce changes in cervical and lumbar spine posture and proprioception in the cervical spine.

The stern tube bearing is installed to the stern tube and stern boss casting by using the method of the force pressured fitting. The adequate value of the interference between the stern tube bearing and casting should be considered owing to the slip. In this study, to review and compare the fitting force and the contact pressure, the theory of thick walled cylinder is considered to clarify the formula which received from the maker. Also the fitting force and contact pressure are calculated by using the standard value of interference, Young`s modulus, Poisson`s ratio and friction coefficient.

In this study, dynamic deformation behavior of submicrocrystalline aluminum alloy was established with respect to equal-channel angular (ECA) pressing routes such as A, B, and C. After 8-pass ECA pressings, the deformed samples, regardless of the routes applied, were consisted of ultrafine grains together with high dislocation density near the boundaries. Microstructural observation revealed that the sample deformed via route B showed more diffused diffraction pattern than those deformed via route A and C, suggesting the fact that route B was most effective for a rapid evolution in the grain boundary orientation from low-angle to high-angle characteristics. In the torsion tests, the shear stress decreased once reaching the maximum point. This maximum was the highest in the sample deformed via route B, and decreased in the order of the route C and route A. The dynamic deformation was explained based on microstructural uniformity associated with ECA pressing routes.

The effect of equal-channel angular pressing (ECAP) route on the high-strain-rate deformation behavior of ultra-fine-grained aluminum alloy was investigated. The 8-pass ECAPed specimens deformed via three different routes consisted of ultra-fine grains 0.5 μm in size, and contained a considerable amount of second-phase particles, which were fragmented and distributed in the matrix. In the torsion tests, the maximum shear stress significantly increased with increasing number of ECAP passes, while the maximum shear stress and fracture shear strain were lowest in the specimen deformed via route A among the three 8-pass ECAPed specimens. Observation of the deformed area beneath the fractured surface revealed the adiabatic shear bands of 100 μm in width in the specimen deformed via route A, which minimized the maximum shear stress and fracture shear strain, whereas they were hardly formed in the specimens deformed via route B or C. The formation of adiabatic shear bands was explained in terms of critical shear strain, deformation energy required for void initiation, and microstructural homogeneity related to ECAP routes.

This study investigated high-temperature dynamic compressive properties of two Zr-based monolithic amorphous alloys. Dynamic compressive tests were conducted in the temperature range from room-temperature to 380 °C using a compressive Kolsky bar, and then the test data were analyzed in relation to microstructure and fracture mode. Both the maximum compressive stress and total strain of the two amorphous alloys decreased with increasing test temperature because shear bands could propagate rapidly as the adiabatic heating effect was added at high-temperatures. Above the glass transition temperature ( T g ), the total strain decreased more abruptly than the total strain measured between room-temperature and 300 °C because of the crystallization of amorphous phases. The alloy having lower T g and larger Δ T showed the better total strain because of the lower viscosity, which could favorably affect the ductility.

Effects of test temperature and alloy composition on dynamic deformation behavior of Zr -based amorphous alloys were investigated in this study. Dynamic compressive tests were conducted in the temperature range from room temperature to 380°C using a compressive Kolsky bar. Dynamic compressive test results indicated that both maximum compressive stress and total strain of the amorphous alloys decreased with increasing test temperature because shear bands could propagate rapidly as the adiabatic heating effect was added at high temperatures. Maximum compressive stress and total strain of the alloy containing ductile β crystalline phases were higher than those of the monolithic amorphous alloys over the tested temperature range because β phases played a role in forming multiple shear bands. The alloys having lower T g or ductile phases had more excellent dynamic properties than the LM1 alloy.

In this study, dynamic deformation and fracture behavior of ultra-fine-grained dual phase steels fabricated by equal channel angular pressing (ECAP) was compared with that of conventionally annealed ultra-fine-grained steels. In the ECAPed conventionally annealed specimen, pearlites were decomposed, and the ferrite grain size increased up to 0.5 μm. The intercritically annealed specimen consisted of dual phases of equiaxed ferrites and blocky martensites (volume fraction; 35%, size; 1 μm). The dynamic torsional test results indicated that maximum shear stress of the annealed specimens was lower than that of the as-pressed specimen, but fracture shear strain was higher. These results suggested that annealing or promoting dual phase microstructures of the ECAPed specimens could be a good way to increase the fracture resistance under dynamic loading, as it reduced or prevented the formation of adiabatic shear bands or voids. In particular, the ECAPed ultra-fine-grained dual phase steel can be more reliably used under dynamic conditions since it overcomes the shortcomings of reduced strain hardenability, ductility, and dynamic properties.

This study investigates the high-temperature dynamic compressive deformation behavior of Zr-based amorphous alloy and amorphous matrix composite containing ductile β crystalline phases. Dynamic compressive tests were conducted in the temperature range from room temperature to 380 °C using a compressive Kolsky bar, and then the test data were analyzed in relation to microstructure and fracture mode. Dynamic compressive test results indicated that both the maximum compressive stress and the total strain of the amorphous alloy and composite decreased with the increasing test temperature because shear bands could propagate rapidly as the adiabatic heating effect was added at high temperatures. Above the glass transition temperature, total strain decreased more abruptly than that measured between the room temperature and 300 °C according to the crystallization of amorphous phases. The maximum compressive stress and the total strain of the amorphous composite were higher than those of the amorphous alloy in the overall test temperature range because β phases played a role in forming multiple shear bands. These findings suggested that applying the evaluation criteria for mechanical properties measured under room temperature quasi-static loading could cause risks when the Zr-based amorphous alloy and composite were used at high temperatures under dynamic loading conditions.

Dynamic torsional deformation behavior of an ultra-fine-grained dual-phase steel fabricated by equal channel angular pressing (ECAP) was investigated and compared with that of an equal channel angular pressed (ECAPed) ultra-fine-grained low-carbon steel. Tensile and dynamic torsional tests were conducted on these two steels, and the deformed microstructures were observed to investigate the dynamic deformation behavior. The ECAPed low-carbon steel consisted of very fine, elongated ferrite-pearlite grains of 0.5 μm in size, and the ECAPed dual-phase steel consisted of ferrite-martensite grains of 1 μm in size. The dynamic torsional test results indicated that maximum shear stress of the dual-phase steel was lower than that of the conventional steel, but that fracture shear strain was higher in the dual-phase steel. Some adiabatic shear bands were observed at the gage center of the dynamically deformed torsional specimen of the low-carbon steel, but they were not observed in the dual-phase steel because localized deformation was alleviated by the increased strain hardenability. These results suggested that the ECAPed ultra-fine-grained dual-phase steel could be a good way to increase the fracture resistance under dynamic loading as the formation of adiabatic shear bands was reduced or prevented.

Dynamic deformation and fracture behavior of Zr-based bulk metallic glass (BMG) and BMG composite containing dendritic β phases was investigated in this study. Dynamic compressive test results indicated that both maximum compressive stress and total strain of the BMG and BMG composite decreased with increasing test temperature because shear bands could propagate rapidly as the adiabatic heating effect was added at high temperatures. Above the glass transition temperature, total strain decreased more abruptly due to crystallization of amorphous phases. Maximum compressive stress and total strain of the BMG composite were higher than those of the BMG because β phases played a role in forming multiple shear bands. The BMG composite having more excellent dynamic properties than the BMG can be more reliably applied to the structures or parts requiring dynamic properties.

Let L := L(G) denote the classical modular Lie algebra of -type over an algebraically closed field F of characteristic p > 5 associated with some simple and simply connected algebraic group G. After the prototypes of those for -type in [4], we shall search for irreducible (=simple) L-modules in this paper.

Dynamic deformation and fracture behaviors of Zr-based amorphous alloys were investigated in this study. Quasi-static and dynamic compressive tests were conducted using a universal testing machine and a compressive Kolsky bar, respectively, and then the test data were analyzed in relation to microstructure and fracture mode. Quasi-static compressive test results indicated that the compressive strength of the amorphous alloy containing dendritic β phases was similar to that of the amorphous alloy, while the ductility was better. Under dynamic loading, the maximum shear stress and ductility of the amorphous alloys were considerably lower than those under quasi-static loading because of the decreased resistance to fracture. The deformation and fracture behaviors occurring under quasi-static and dynamic loading conditions were explained by fracture mechanisms observed on fractured surfaces.

[Purpose] The present study was performed to identify the effect of a home exercise program on the self-reported disability index and gait parameters in patients with lumbar spinal stenosis (LSS). [Methods] Fifteen patients with LSS were enrolled in this study and were trained in a 4-week home exercise program (40 min/day). All patients were evaluated with three self-reported disability indices (Oswestry Disability Index, Roland-Morris Disability Questionnaire, and Spinal Stenosis Scale), and gait parameters were assessed using a GAITRite system before and after the home exercise program. [Results] Patients with LSS showed significant decreases in the self-reported questionnaire scores and pain intensity after the home exercise program. However, the gait parameters did not significantly change. [Conclusion] These findings suggest that home exercise programs can improve self-reported questionnaire scores and decrease pain in patients with LSS.

In the present study, ultrafine-grained microstructures of a conventional 5083 aluminum alloy were fabricated by equal-channel angular pressing, and their dynamic deformation and fracture behavior were investigated. Dynamic torsional tests were conducted on four aluminum alloy specimens using a torsional Kolsky bar, and then the test data were analyzed in relation to microstructures, tensile properties, and adiabatic shear-banding behavior. The equal-channel angular-pressed (ECAP) specimens consisted of ultrafine grains and contained a considerable amount of second-phase particles, which were refined and distributed homogeneously in the matrix as the equal-channel angular pressing pass number increased. The dynamic torsional test results indicated that the maximum shear stress increased, while the fracture shear strain remained constant, with increasing equal-channel angular pressing pass number. Observation of the deformed area beneath the dynamically fractured surface showed that a number of voids initiated mainly at second-phase particle/matrix interfaces and that the number of voids increased with increasing pass number. Adiabatic shear bands of 200 to

The correlation of microstructure and Charpy V-notch (CVN) impact properties of a high-toughness API X70 pipeline steel was investigated in this study. Six kinds of steel were fabricated by varying the hot-rolling conditions, and their microstructures, effective grain sizes, and CVN impact properties were analyzed. The CVN impact test results indicated that the steels rolled in the single-phase region had higher upper-shelf energies (USEs) and lower energy-transition temperatures (ETTs) than the steels rolled in the two-phase region because their microstructures were composed of acicular ferrite (AF) and fine polygonal ferrite (PF). The decreased ETT in the steels rolled in the single-phase region could be explained by the decrease in the overall effective grain size due to the presence of AF having a smaller effective grain size. On the other hand, the absorbed energy of the steels rolled in the two-phase region was considerably lower because a large amount of dislocations were generated inside PFs during rolling. It was further decreased when coarse martensite or cementite was formed during the cooling process.

The dynamic deformation behavior of ultrafine-grained low-carbon steels fabricated by equal-channel angular pressing (ECAP) was investigated in this study. Dynamic torsional tests, using a torsional Kolsky bar, were conducted on four steel specimens, two of which were annealed at 480 °C after ECAP, and then the test data were compared in terms of microstructures, tensile properties, and adiabatic shear-band formation. The equal-channel angular pressed specimen consisted of very fine, equiaxed grains of 0.2 to 0.3 µm in size, which were slightly coarsened after annealing. The dynamic torsional test results indicated that maximum shear stress decreased with increasing annealing time, whereas fracture shear strain increased. Some adiabatic shear bands were observed at the gage center of the dynamically deformed torsional specimen. Their width was smaller in the equal-channel angular pressed specimen than in the 1-hour-annealed specimen, but they were not found in the 24-hour-annealed specimen. Ultrafine, equiaxed grains of 0.05 to 0.2 µm in size were formed inside the adiabatic shear band, and their boundaries had characteristics of high-angle grain boundaries. These phenomena were explained by dynamic recrystallization due to a highly localized plastic strain and temperature rise during dynamic deformation.

The effects of microstructure on inverse fracture occurring in the hammer-impacted region were analyzed after conducting a drop-weight tear test (DWTT) on high-toughness pipeline steels. Three kinds of steels were fabricated by varying the alloying elements, and their microstructures were varied by the rolling conditions. The pressed-notch (PN) or chevron-notch (CN) DWTT and Charpy V-notch (CVN) impact tests were conducted on the rolled steel specimens, and the results were discussed in comparison with the data obtained from CVN tests of prestrained specimens. In the hammer-impacted region of the DWTT specimens, abnormal inverse fracture having a cleavage fracture mode appeared, and the inverse fracture area correlated well with the upper-shelf energy (USE) obtained from the CVN test and with the grain size. The steel specimens having a higher USE or having coarse polygonal ferrite tended to have a larger inverse fracture area than those having a lower USE or having fine acicular ferrite. This was because steels having a higher impact absorption energy required higher energy for fracture initiation and propagation during the DWTT. These results were confirmed by the CVN data of prestrained steel specimens.

Equiaxed and bimodal microstructures containing very fine α2 (Ti3Al) particles were produced by over-aging of a Ti–6Al–4V alloy, and effects of α2 precipitation on dynamic deformation behavior and ballistic performance were investigated in comparison with unaged microstructures. According to the dynamic torsional test data, maximum shear stress and fracture shear strain were higher in the aged bimodal microstructure than in aged equiaxed microstructure, and the possibility of the adiabatic shear band formation was less likely in the former than in the latter. In the ballistically impacted region of the aged equiaxed microstructure, a number of adiabatic shear bands and cracks were observed to be formed along plastic flow lines. In the case of the aged bimodal microstructure, shear bands were found in limited areas near the perforated surface, and their number was smaller than that of the aged equiaxed microstructure. Thus, the ballistic performance of the aged bimodal microstructure was better than that of the equiaxed microstructure, which was consistent with the dynamic torsional-test results. Also, the ballistic performance of the aged microstructures was slightly increased over the unaged microstructures. This was explained by the improvement of dynamic torsional properties and by the lower possibility of adiabatic shear band formation.

[Purpose] The purpose of this study was to investigate the intra-rater reliability of measures of scapular protraction strength using a novel method. [Subjects] Forty-nine healthy subjects participated in this study. [Methods] Subjects performed maximal isometric scapular protraction on the left and right sides in the supine and seated positions. During scapular protraction, resistance was applied to the olecranon, and the strength of scapular protraction was measured using a load cell. Intra-rater reliability was calculated as the intra-class correlation coefficient (ICC3,1). [Results] High intra-rater reliability scores (0.97-0.98) for scapular protraction strength were observed in the supine and seated positions. [Conclusion] These findings demonstrate that the method described herein may provide a more reliable and convenient method to measure scapular protraction strength than common current practice does.

Background Abdominal strengthening exercises are important for stroke patients; however, there is a lack of research on therapeutic exercises for increasing abdominal muscle activity in stroke patients. Objective We investigated the effects of non-paretic arm exercises using a tubing band on abdominal muscle activity in stroke patients. Methods In total, 18 hemiplegic subjects (13 males, 5 females) were recruited. All subjects performed non-paretic arm exercises involving three different shoulder movements (extension, flexion, and horizontal abduction) using an elastic tubing band. Surface electromyography (EMG) signals were recorded from the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles bilaterally during non-paretic arm exercises. Results EMG activities of abdominal muscles during non-paretic arm extension and horizontal abduction were increased significantly versus shoulder flexion when subjects performed the arm exercise in a seated position. Muscle activity of the EO was significantly greater in the paretic than the non-paretic side during non-paretic arm extension and horizontal abduction. Conclusions We suggest that non-paretic arm extension and horizontal abduction exercises using an elastic tubing band may be effective in increasing abdominal muscle activity.

Altered gait patterns with lumbar-flexed posture threaten the quality of life in patients with lumbar spinal stenosis; however, few studies have developed management strategies to improve gait patterns and lumbo-pelvic posture. The present study investigated the effects of lumbo-pelvic postural taping on pelvic tilt, spatiotemporal gait parameters, and pain during walking in patients with lumbar spinal stenosis.The pelvic tilt and gait parameters were assessed in 20 patients with lumbar spinal stenosis before sustained walking using a palpation meter and GAITRite system, respectively. Next, the participants were asked to walk on the ground for 20 min or until they complained of symptoms of neurogenic claudication. Pelvic tilt and gait parameters were measured immediately after the manifestation of neurogenic claudication followed by the application of lumbo-pelvic postural taping. The participants rated the pain intensity using a visual analog scale. Changes in dependent variables among the conditions were analyzed using a one-way repeated-measures analysis of variance.The results show a decreased pelvic anterior tilt, walking velocity, and step and stride lengths, as well as an increased base of support and pain after severe symptoms of neurogenic claudication (P0.05). However, a greater pelvic anterior tilt, faster walking velocity with a longer step and stride length, and decreased base of support and pain were found after the application of postural taping (P≤0.001).These findings suggest that lumbo-pelvic postural taping can provide beneficial management for improving gait patterns and lumbo-pelvic posture in patients with lumbar spinal stenosis.