• Magazine of the Korean Society of Agricultural Engineers
• /
• v.27 no.2
• /
• pp.47-56
• /
• 1985

Wasting fiberous residues from the cutting processes of steel materials at an iron-Works were mixed with concrete. The strength and toughness of steel fiber concrete with different steel contents were tested in a laboratory. The test results showed that the steel fiber residues can be used for the reinforcement of concrete. The potential applications of such product include floor constructions for facilities like dairy barns, grain storages, and machinery shops. The test results are as follows. 1. The compressive strengths of steel fiber concrete with one percent steel content by volume were 20 percent greater than that of plain concrete. The treatments also increased the concrete toughness by 96 percent. 2. When applied to tensile forces, the steel fiber concrete showed the increased strengths by 20 percent, and the toughness by 48 percent. 3. The steel content levels greater than or equal to 1.5 percent by volume resulted in the decreases of the compressive and tensile strengths of steel fiber concrete by 10 percent as compared to plain concrete. The concrete toughness increased with the steel contents. 4. The reinforcement effects of steel fiber depend on the quality of fiber material being used. Good steel fiber for concrete reinforcement appears to be uniform in shape and component, fine and long, and round-shaped.

• Journal of the Society of Naval Architects of Korea
• /
• v.31 no.3
• /
• pp.59-64
• /
• 1994

A study was conducted to investigate the propeller singing place of an 86, 000 ton Deadweight Crude Oil Tanker. In preliminary study, proper use of finite element analysis was verified by comparing with the result of hammering test in the air. Then the finite element analysis was carried out for the blade in the water and compared with the noise measurement during sea trial, which enabled to confirm the local resonances of blade structure. Result of the study showed that the singing occurred most probably at trailing edges on the blade tip over 95% of propeller diameter. Owing to edge cutting of a successfoul remdial action, the singing excitation forces seemed to be reduced whereas the vibration characteristics of the blade was not changed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.20 no.2
• /
• pp.23-31
• /
• 2021

Surface texturing is a promising route to reduce the friction forces between two surfaces in sliding contact. To this end, the fabrication of micro dimples is one of the most widely used surface texturing methods. According to published results, textured surfaces with elliptical micro dimples offer the best friction performance. Therefore, we fabricated elliptical micro dimples on carbon steel (SM45C) by using dual frequency vibration assisted machining. High and low frequencies of 16.3 kHz and 230 Hz were applied to the 3D resonant elliptical vibrator. The 3D resonant elliptical vibrator with a triangular cubic boron nitride insert was assembled on a computer numerically controlled turning lathe. Oval micro dimples of various profiles were manufactured on carbon steel. In terms of the profile of the elliptical micro dimples, the experimental results indicated that the average micro dimple width and depth were 112 ㎛ and 7.7 ㎛. These dimensions are closely related to the cutting conditions and can be easily controlled.

• Journal of the Korean Society for Precision Engineering
• /
• v.11 no.5
• /
• pp.42-55
• /
• 1994

Presently, abrasive processing is on eof several methods for cutting and grinding brittle materials, and high quality in dimensional accuracy and surface roughness are often required as a structural components, therefore most of them has to be ground. In manufacturing of tungsten-carbide components, grinding by diamond wheel is usually adopted in order to provide configurational and dimensional accuracy to the components. The present study proposes the experi- mental research of optimum condition to the high quality surface grinding of the WC-Co material using diamond abrasive wheel in order to minimize the damage on the ground surface and to pursue the precise dimension by conventional grinding machine. Brief investigation is carried out to decrease the dressing is constant, theoretical grinding effect such as machining precision is changed according to the speed of workpiece. Accordingly, normal and tangential grinding forces, which are Fn, Ft were analyzed for the machining processes of WC-Co material to obtain optimum grinding conditions, 3-point bending test is carried out to check machining damage on the ground surface layer, which is one of sintered brittle materials.

• Journal of Trauma and Injury
• /
• v.37 no.1
• /
• pp.1-5
• /
• 2024

The aim of this paper was to review the biomechanics of knife injuries, including those that occur during stabbing rampages. In knife stab attacks, axial force and energy were found to be 1,885 N and 69 J, respectively. The mean velocity of a stabbing motion has been reported to range from 5 to 10 m/sec, with knife motions occurring between 0.62 and 1.07 seconds. This speed appears to surpass the defensive capabilities of unarmed, ordinarily trained law enforcement officers. Therefore, it is advisable to maintain a minimum distance of more than an arm's length from an individual visibly armed with a knife. In training for knife defense, particularly in preparation for close-quarter knife attacks, this timing should be kept in mind. Self-inflicted stab wounds exhibited a higher proportion of wounds to the neck and abdomen than assault wounds. Injuries from assault wounds presented a higher Injury Severity Score, but more procedures were performed on self-inflicted stab wounds. Wound characteristics are not different between nonsuicidal self-injury and suicidal self-wrist cutting injuries. Consequently, trauma surgeons cannot determine a patient's suicidal intent based solely on the characteristics of the wound. In Korea, percent of usage of lethal weapon is increasing. In violence as well as murders, the most frequently used weapon is knife. In the crimes using knife, 4.8% of victims are killed. Therefore, the provision of prehospital care by an emergency medical technician is crucial.

• Korean Journal of Food Science and Technology
• /
• v.52 no.4
• /
• pp.403-408
• /
• 2020

The quality characteristics of fish cakes containing different amounts of mealworm powder were analyzed. The moisture content decreased while water absorption index increased with the addition of mealworm powder. The L value was decreased but a value was increased as the amount of mealworm powder added increased. The hardness and cutting forces were 2.63 and 0.09 kg, respectively, in the 0% fried fish cake. With an increase in the amount of mealworm powder, the hardness and cutting force increased to 3.18 and 0.14 kg in the 9% fried fish cake. The pH did not differ with the addition of mealworm powder. During the sensory evaluation, 0 and 3% groups had the highest scores in color, flavor, taste, texture and overall acceptance. These scores decreased with increasing mealworm powder content. Based on the results of the quality characteristics and sensory evaluation, the amount of mealworm powder addition suitable for fish cake production was 3%.

• Korean Journal of Food Science and Technology
• /
• v.25 no.3
• /
• pp.232-237
• /
• 1993

The rheological properties of hard red winter, western white and Australian standard white wheat flours and of HRW-WW and HRW-ASW wheat flour blends having the same protein content were studied. Cooking properties of dry noodles prepared from HRW-WW and HRW-ASW wheat flour blends were also investigated. The noodles were prepared with salt and alkaline reagent. The salt and alkaline concentrations used were 1.7% and 0.17%. respectively, based on the weight of wheat flour. The alkaline reagent was an equal mixture of sodium carbonate and potassium carbonate. The HRW-ASW wheat flour blend had higher farinograph absorption and slightly stronger curve than HRW-WW wheat flour blend. Salt decreased the absorption of wheat flours by 2 and of wheat flour blends by 1%. However, alkaline reagent essentially had no effort on farinograph absorption. Salt and alkaline reagent strengthened the dough of wheat floors and wheat flour blends, with the former being more effective. No significant differences in pasting properties between HRW-WW and HRW-ASW wheat flour blends by amylograph were observed. There were no significant differences in rate of increase of weight or volume between noodles prepared from HRW-WW and HRW-ASW wheat flour blends. Alkaline reagent did not affect the weight gain of noodles hut lowered the volume gain. Breaking force of dry noodles and cutting force of cooked noodles were similar between the two noodles. Alkaline reagent increased both the breaking and cutting forces of noodles. Sensory evaluation revealed that the noodles prepared from HRW-WW and HRW-ASW wheat flour blends were slightly different. but not different from each other by preference test.

• Korean Journal of Agricultural Science
• /
• v.8 no.2
• /
• pp.224-230
• /
• 1981

Threshing forces of seven varieties, that is, three Japonica type varieties-Irri 348, Irri 345, and Milyang 15, and four Indica type varieties-Milyang 23, Irri 342, Suweon 294 and Suweon 287-, which have been cultivated in the standard fertilization field being at Chungnam Provincial Office of Rural Development, Youseong, Chungnam-do, they were measured every other day in the period from September 28 to October 20 which were included the proper harves ting time. Also the threshing forces were checked in three-dimensional directions. Relationships between threshing forces and moisture contents of the unthreshed rice were examined in the laboratory as dried in the natural condition. The results of this study were as follows; 1. The mean threshing force of Japonica type varieties was about 1969r. and that of Indica type varieties was about 113gr. when external force was loaded in the direction parallel to the grain. 2. The threshing force bent to the grain was about 9.8through 28.2gr. equal to 7 through 21 percent to the threshing force parallel to the grain in Indica type varieties meanwhile about 59.8 through 115.0gr equal to 33 through 50 percent in Japonica type varieties. 3. Under the warmer temperature than $0^{\circ}C$, the change of threshing forces was not great in this experimental period on the harvesting dates. 4. The threshing force decreased s lightly as moisture content decreased in natural drying under the shade after cutting. 5. The threshing force of the lower portion was a little biger than that of the upper portion in an ear.

• Journal of National Security and Military Science
• /
• s.7
• /
• pp.55-89
• /
• 2009

This article aims to critically review recent U. S. RMA-centered theories of warfare having prevailed after the 1991-92 Gulf War upon which the current ROKA military transformation project, the Vision 2020, largely based. In order to evaluate validity as a universal warfighing theory of NCW (Network Centric Warfare) and EBO (Effects-Based Operations), this article reviews the intrinsic strength and weakness of the theories as well as results of several recent wars that the U. S. Army conducted based on doctrines derived form such theories, In addition, this article examines the impact of certain military technology or weapon system in some well-known historical wars to draw lessons regarding the relationship between technology(weapon system) and military victory. Historical examples has shown that victories in war were not achieved by new technologies alone in most cases. Rather military victories tended to owe to combination of new technology, original doctrine and well conceived organization. Although the U. S. Armed Forces showed brilliant records of operational successes anchored on the system of PGMs and NCW concepts in Iraq (1991-92; 2003) and Afghanistan (2001-02), it must be pointed out that the operational successes did not bring about political ones in cases of Iraq and Afghanistan. It reminds us of perils of too technologically tilted approach to the conduct of war. In sum, one ought to recognize that superior technology nowadays became a necessary condition of success but is not yet a sufficient condition, the ROKA needs to be abreast with development trends of military technologies and related theoretical concepts, it need not too be in a hurry in adopting cutting edged war-making technologies at the expense of large amount of budget. The essay recommends for the ROKA several basic requirements for coping with conduct of future wars as well as establishing a 'Korean style military thought'; (1) Recognition of importance of technology in conduct of war; (2) Imposition of officer self-study hours in working days; (3) Establishing a lifestyle of military professionalism in the Korean officer corps; (4) Setting up small or large groups of think-tanks that are specialized in army doctrinal formulation.

• Korean Journal of Food Science and Technology
• /
• v.23 no.5
• /
• pp.642-645
• /
• 1991

The rheological properties of wheat flours and corn starch and cooking properties of dry noodle in the presence of calcium phosphate hydroxyapatite(Ca-P) were studied. The additive($0.2{\sim}0.8%$) had essentially no effects on farinograms of strong and all-purpose wheat flours, however, they decreased the amylograph pasting temperature and increased the peak viscosity of flours, which was more pronounced in all-purpose flour. The cooking properties of dry noodles in the presence or absence of the Ca-P showed no significant differences, but the cutting forces of cooked noodles were increased by Ca-P at 0.4%. The pasting properties of corn starch in the presence of Ca-P($0.2{\sim}0.8%$) were similar to those of wheat flour. The gelatinization temperature of corn starch by differential scanning calorimeter decreased by $1^{\circ}C$ in the presence of 0.4% Ca-P. The time constant, a reciprocal of rate constant, of corn starch gel was slightly increased in the presence of 0.2 or 0.4% Ca-P.