• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.10
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• pp.810-815
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• 2008

To enhance aerodynamic efficiency of the Smart Un-manned Aerial Vehicle(SUAV) during the transition period, wingtip fence is attached at the end of wing. The application of wingtip fence is to reduce the effect of the separated flow caused by the nacelle on the wing especially when the tilting angle of nacelle is more than 30 degrees. To compare the effect of with and without wingtip fence, flow visualization and measurement of the aerodynamic coefficients using the pyramidal type external balance are done. Result of forces and moments measurement shows that the slope of lift coefficient is increased 18% and rolling moment of SUAV especially 60 & 90-degree tilting is changed in favorable manners with wingtip fence.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1509-1520
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• 1998

An experiment was carried out for the fully developed turbulent flow of water in tube coils on the condition of uniform heat flux. The present work was conducted for various ranges for Dean number(1794~1321), Prandtl number (2.5~4.5), curvature ratio parameters (22~60). Heat transfer to steady viscous flow in coiled tubes of circular cross section was studied for fully developed velocity and temperature fields under the thermal boundary condition of uniform heat flux. The peripherally local Nusselt number correlated as a function of Dean and Prandtl numbers. We studied the flow in heat coiled tubes under the influence of both centrifugal and buoyancy forces in order to gain insight into the flow pattern. In the present study, we obtained three emperical formulas, $Nu_v=0.0231Re^{0.84}Pr^{0.4}(a/R)^{0.13}$ (vertical) $Nu_c=0.0241Re^{0.86}Pr^{0.4}(a/R)^{0.08}$ (corrugated) $Nu_h=0.0227Re^{0.84}Pr^{0.4}(a/R)^{0.09}$ (horizontal).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.840-840
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• 2003

Operational Modal Analysis (OMA) is a technique for identification of modal parameters by measurement of only the system's response. On many lightweight structures, such as load-speaker cones and disk drive read/write heads, is impossible or impractical to measure the input forces. Another characteristic of lightweight structure is their sensitivity to mass loading from sensors. The Scanning Laser Doppler Vibrometry(SLDV) allows response measurements to be taken without mass loading. One disadvantage of OMA testing compared to tradition input output modal testing is the OMA mode shapes are un-scaled. This means that the mode shape obtained from an OMA test can not used for analytical structural modification studies. However, the un-scaled mode shapes from an OMA test can be used to update a Finite Element Model (FEM). The updated FEM can then be used to analytically predict the effect of structural modifications. This paper will present the results of an OMA test performed on a simple plate and motor in operating conditions. The un-scaled mode shapes from this test will be used to update a FEM model of the system. The updated FEM model will be then be used to predict the effect of attaching a mass to the plate. The shapes predicted by the FEM for the modified system will be compared to a second OMA test on the modified system

• Anxiety and mood
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• v.10 no.1
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• pp.59-67
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• 2014

Objective : To obtain the incidence rate of anxiety disorders among the active duty Korean military personnel, who visited the military hospitals from 2011 to 2013, this descriptive epidemiological study was performed. Methods : After acquiring the data for the anxiety disorders from Defense Medical Statistics Information System, the annual incidence rates were analyzed by forces, position status, and specific disease entities. Results : One thousand, nine hundred and thirteen (1,913) active duty male military personnel were diagnosed with any kinds of anxiety disorders in their first visit to the psychiatric outpatient department (OPD). The total OPD visit counts were 7,870 during the same period. Anxiety disorder, NOS was the most frequent disorder, followed by panic disorder. While the incidence rate for anxiety disorder, NOS decreased, panic disorder displayed increasing tendency. Stress-related disorders and obsessive-compulsive disorder were positioned third and fourth, respectively, for the number of first visit and they both showed decreasing tendency in annual incidence rates. Social anxiety disorder, specific phobias, generalized anxiety disorder (GAD) and mixed anxiety-depressive disorder followed next. The annual incidence rates for anxiety disorders showed decreasing tendency, particularly evident in army soldiers. However, naval officers showed higher anxiety disorder incidence rate compared to those of the army and the air forces. Conclusion : Comparing to general population, panic disorder was higher while specific phobias and GAD were lower in the Korean military. It is interesting to observe higher incidence rate for anxiety disorder in naval officers and warrants further evaluation.

• Journal of Mechanical Science and Technology
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• v.20 no.5
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• pp.643-651
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• 2006

The theory for a novel fault-tolerant 4-active-pole homopolar magnetic bearing is developed. If any one coil of the four coils in the bearing actuator fail, the remaining three coil currents change via an optimal distribution matrix such that the same opposing pole, C-core type, control fluxes as those of the un-failed bearing are produced. The hompolar magnetic bearing thus provides unaltered magnetic forces without any loss of the bearing load capacity even if any one coil suddenly fails. Numerical examples are provided to illustrate the novel fault-tolerant, 4-active pole homopolar magnetic bearings.

• The Journal of the Convergence on Culture Technology
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• v.10 no.4
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• pp.17-22
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• 2024

The war that broke out on October 7, 2023 is prolonging and expanding into the Middle East. Although the damage from war is increasing, humanitarian aid to the Gaza Strip has been halted due to UNRWA's deviant actions. Powerful countries have suspended support, and the UN is appealing for support for the Gaza Strip. All damage is borne by civilians in the Gaza Strip, especially women, children, and the elderly. Israel has selected an evacuation zone and evacuation route in the Gaza Strip and established a humanitarian aid route in the border area. However, Hamas's resistance in underground tunnels, using civilian-dense areas and civilian facilities such as hospitals and schools as shields, further amplified civilian casualties. This Israel-Hamas war requires the international community to approach it from a human security perspective. We must strengthen the UN's functions and roles to ensure that humanitarian supplies reach the field and humanitarian intervention forces ensure human dignity and basic rights. We must restore the credibility of the UN's role through the Israel-Hamas war. In addition, Korea should urge the introduction of humanitarian aid and goods, and provide humanitarian goods such as daily necessities and medicine. We must also prepare for deployment as a member of the UN peacekeeping force in the future. These activities will help Korea develop into a model country that fulfills its role as a 'global pivotal nation' and will have a virtuous cycle of international support in the event of a future crisis on the Korean Peninsula.

• Journal of Biosystems Engineering
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• v.27 no.2
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• pp.89-96
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• 2002

The trend of consumption of vegetable soybeans is increasing because they are recognized as the clean vegetable. The works requiring the most intensive labor are threshing and seperation ones, and they form about 80% of total labour for vegetable soybeans production. It is necessary to develop the vegetable soybeans-thresher for the sake of cost down of vegetable soybeans production. The purpose of this study is to acquire the basic informations to design of the vegetable soybeans-thresher. We make the experimental system which control the speed of threshing cylinder and the teeth gap and investigate the detachment forces. The result are as follows ; The ratio of un-threshed soybeans-pod to stem after threshing work is decreasing as the threshing cylinder speed increases: 0.0% and 2.8% at 55m/s and 18m/s of threshing cylinder speed respectively. Also the ratio of un-threshed soybeans-pod to stem is shown as 2.0% below in the condition of 64~160mm of teeth gap and over 28m/s of threshing cylinder speed. The damaged pod ratio of detached soybeans after threshing work is decreasing as the threshing cylinder speed increases: 4.8% and 1.3% at 55m/s and 18m/s of threshing cylinder speed respectively. The minimum damaged pod ratio of detached soybeans are shown as 1.0%, 1.5% and 1.9% at 18m/s, 28m/s and 37m/s of threshing cylinder speed respectively. The average detachment forces of pods are shown as 1.5kg$_{f}$ for 3 grains, 1.2kg$_{f}$ for 2 grains and 0.8kg$_{f}$ for 1 grain respectively. The maximum detachment force of pod is shown as 2.7kg$_{f}$ for 3 grains. grains.

• Journal of Korea Water Resources Association
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• v.54 no.7
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• pp.463-474
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• 2021

The various external forces can cause inundation in coastal areas. This study is to analyze regional characteristics caused by single or compound external forces that can occur in coastal areas. Storm surge (tide level and wave overtopping) and rainfall were considered as the external forces in this study. The inundation analysis were applied to four coastal areas, located on the west and south coast in Republic of Korea. XP-SWMM was used to simulate rainfall-runoff phenomena and 2D ground surface inundation for watershed. A coupled model of ADCIRC and SWAN (ADCSWAN) was used to analyze tide level by storm surge and the FLOW-3D model was used to estimate wave overtopping. As a result of using a single external force, the inundation influence due to storm surge in most of the coastal areas was greater than rainfall. The results of using compound external forces were quite similar to those combined using one external force independently. However, a case of considering compound external forces sometimes created new inundation areas that didn't appear when considering only a single external force. The analysis considering compound external forces was required to reduce inundation damage in these areas.

• Journal of National Security and Military Science
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• s.13
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• pp.1-41
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• 2016

US 8th Army in the attack on the Western Front was a situation that was frustrated by the 13th Corps Communist army. To this time support this, goals that have been granted to the US 1st Marine Division that initiated the attack in Mupyonri direction, lack the potential to achieve was not decisive. It was a operation specific erroneous judgment that occurred because there was no one accurately grasp the battlefield of the situation the wrong UN Forces Command. Tactical victory can be to maximize the operation outcomes. However, there is no possible failure of the operation is to expand the tactical success. This is because the failure of the operation, because directly linked to the success or failure of the war. Tactical victory can be to maximize the operation outcomes. However, operation specific failure is not it possible to expand the tactical victory. Therefore tactical success of the US 1st Marine Division, can not compensate for operation specific failure of the United Nations Forces Command. However, Chinese Communist Army 9th Corps is obsessed only victory of tactics to annihilate the US 1st Marine Division, by being fixation to the Chosin whole area, it was not possible to run a operational operation. Therefore tactical success df the US 1st Marine Division, Chinese Communist Army 9th Corps is to extinguish the ability to increase the number of the 13th Corps of the Western Front, 8th Army US have contributed to have escaped the crisis. In addition, the US 10th Corps while maintaining the combat force, by an important role to withdraw through the sea, was able to complement the misjudgment of the operation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.2
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• pp.17-23
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• 2002

A cylindrical capacitance-type spindle displacement sensor was developed and its effectiveness as a system to monitor cutting forces during hard turning was tested in this research. The sensor was installed between the face of spindle cover and the chucking element and measured pure radial motion of the spindle under the condition with presence of roundness error at measured surface. To prove the effectiveness of the developed system hard aiming tests using ceramic inserts and tool steel as workpiece were conducted. The workpiece was hardened up to 65 Rc. The variations of pure radial motion of the spindle ware measured during the cutting tests. The signals from the sensor showed the same pattern of cutting force variations from the tool dynamometer due to the progress of tool wear. As the flank wear of the ceramic tool increased both static component of cutting forces and the amount of center shift of spindle orbit increased, Results from the research showed that the developed sensor could be utilized as an effective and cheap on-line sensing device to monitor cutting conditions and tool performance in the un-manned machining center.