• Journal of the Ergonomics Society of Korea
• /
• v.25 no.2
• /
• pp.181-186
• /
• 2006

MSDs(Musculoskeletal Disorders) symptoms related to infants-rearing was evaluated on 207 Korean caregivers who taking care of their infants under 36 months on January and February 2005. In Result, 77 percentages caregivers suffered from MSDs symptoms that occurred more than one time for 1 month during the last one year or last for more than one week (by NIOSH). This results shows that MSDs problems of Korean infants caregivers are very serious. Body parts complained of MSDs symptoms were low back(61%), shoulder(60%), hand/wrist(46%), neck(37%), upper back(35%). Parenting stress of the caregivers who had MSDs symptoms was significantly higher than who didn't showed MSDs symptoms.

• Journal of Sensor Science and Technology
• /
• v.13 no.4
• /
• pp.264-269
• /
• 2004

This paper describes on an advanced technology of 3C-SiC/Si(100) wafer direct bonding using PECVD oxide to intermediate layer for SiCOI(SiC-on-Insulator) structure because it has an attractive characteristics such as a lower thermal stress, deposition temperature, more quick deposition rate and higher bonding strength than common used poly-Si and thermal oxide. The PECVD oxide was characterized by ATR-FTIR. The bonding strength with variation of HF pre treatment condition was measured by tensile strength measurement system. After etch-back using TMAH solution, roughness of 3CSiC surface crystallinity and bonded interface was measured and analyzed by AFM, XRD, and SEM respectively.

• The Journal of Korean Physical Therapy
• /
• v.15 no.2
• /
• pp.52-66
• /
• 2003

The intervertebral disc is a cartilaginous structure that resembles articular cartilage in its biochemistry, but morphologically it is clearly different. It shows degenerative and ageing changes earlier than does any other connective tissue in the body, It is believed to be important clinically because there is an association of disc degeneration with back pain. Degenerative changes in the intervertebral disc are thought to develop as aging, mechanical stress and metabolic factors. Genetic factors may also play a part in the onset or progress of the degenerative process. They, together with environmental factors, may act as determinants of the structural characteristics of the intervertebral disc and produce a tendency to generation, In this short review we outline the morphplogy and biochemistry of normal intervertebral disc and the changes that arise during degeneration. Therefore this study will review degeneration of intervertebral disc, so we will have knowledge about low back pain associated with degenerative change in the intervertebral disc.

• Proceedings of the ESK Conference
• /
• 1997.04a
• /
• pp.100-106
• /
• 1997

The purpose of this study is to measure perceived joint discomfort in the seated and standing position, and to provide a ranking system of joint discomfort measured in this study. Seven male subjects with no history of musculo-skeletal disorders participated in the experiment. Their physical characteristics were: age -$27.6 {\pm}1.8$ years, stature -$171.0 {\pm}5.5cm$, and body weight -$66.4{\pm}9.3kg$. The results showed that perceived joint discomfort was different depending on the human body joints involved in motion and their movement directions, which imply that the human body motions should be classified intoseveral distinct classes that need to be assigned different weights of postural stress. In the seated postion, the hip movement was the most stressful, the back was the second, and the shoulder was the third. Similarly, in standing postures, the hip was given the highest ranking, followed by the back, and the wrist.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1271-1276
• /
• 2008

This study has explained about LED for BLU which is widely used in the kinds of display devices or lighting. It was shown that the open due to delamination were the dominant LED for BLU failure mode and mechanisms from failure analysis of LED samples. Then, we have defined failure as yellowing and 100% reduction of light output intensity of LED for BLU and acceleration factors as temperature and current in Accelerated Life Test(ALT). Finally, we have estimated the Weibull distribution, life-stress relationship, and accelerating factor is used by ALTA Software.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 1996.11a
• /
• pp.964-968
• /
• 1996

The demands of size and quality of large steel shaft forgings for ship building, power plant, steel plant, etc. are rapidly increasing, and some of these productions are manufactured from ingot weighing more than 300 tons. For use as rotating components. shafts require toughness, strength and homogeneity, and therefore are produced through a variety of heat treatments. According to the increase of ingot size, micro- and macrosegregation and also mass effect of the product increase. Thus, special care should be paid to the heat treatment of such large shaft forgings. In this paper, the heat treatment of large shaft forgings such as rotor and back-up roll is calculated using the commercial finite element code SYSWELD. Calculated distributions of temperature and phase are compared with experimental data. The continuous cooling transformation diagram, thermal and mechanical properites of each phase are used. The phase proportion, hardness and residual stress during water quenching are discussed.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.41 no.7
• /
• pp.723-734
• /
• 1992

In this paper, the characteristics of IPMSM(Interior-type Permanent Magnet Synchronous Motor) are simulated using 2-D. finite element method. This paper deals with the following characteristics : air gap flux density considering skew, back e.m.f., torque and inductance. Back e.m.f. is calculated using the flux obtained from the vector potential of FEM solution. Torque is calculated using improved Maxwell stress tensor method and current angle which is obtained from the controller. Direct axis inductance and quadrature axis inductance are also calculated using energy perturbation method. Computed results are found in satisfactory agreement with experimental ones. This method also can be applied for the computation and analysis of the characteristics of SPMSM, current-excited synchronous motor and reluctance motor.

• Journal of the Korean Society for Railway
• /
• v.7 no.1
• /
• pp.1-8
• /
• 2004

A newly-built inverter has to undergo a series of stress tests in the final stage of production line. This can be achieved by connecting it to a dynamometer consisting of a three-phase machine joined by a rigid shaft to a DC load machine. The latter is controlled to create some specific load characteristic needed for the test. In this paper a test method is proposed, in which no mechanical equipment is needed. The suggested test stand consists only of a inverter to be tested and a simulator converter. Both devices are connected back-to-back on the AC-side via smoothing reactors. The simulator operates in real-time as an equivalent load circuit, so that the device under test will only notice the behaviour of a three-phase machine under consideration of the load. In oder to prove rightness of the suggested test method, the simulation and actural experiment carried out emulation for a 2.2kW induction motor.

• Journal of the Korean Geophysical Society
• /
• v.9 no.3
• /
• pp.249-262
• /
• 2006

The 29 May 2004 offshore Uljin, Korea earthquake was predominantly thrust-faulting at a depth of approximately 12 (±2) km. The mainshock attained the seismic moment of M0 =5.41 (±1.87)  1016 N m (Mw = 5.1). The focal mechanism indicates a subhorizontal P-axis trending 264° and plunging 2°. The orientation of P- and T-axis is consistent with the direction of absolute plate motion generally observed within the plates, hence the cause of the May 29 shock is the broad-scale stress pattern from the forces acting on the downgoing slab along the Japan trench and inhibiting forces balancing it. The 29 May 2004 earthquake occurred along a deep seated (~12 km), pre-existing feature that is expressed on the surface as the basement escarpment along the western and southern slopes of the Ulleung basin. The concentrated seismicity along this basement escarpment suggests that this feature may qualify as a seismic zone - the Ulleung basement escarpment seismic zone (UBESZ).

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2019.11a
• /
• pp.241-242
• /
• 2019

This technology is a water leak repair technology using composite materials of concrete structures that block leakage of structures by injecting rapid microcement into the face of underground concrete to block water and injecting flexible glycidylacrylate. Rapid micro cement system repair materials are mixed with fine fibers to improve the flexural sensitivity of the material and to form a layer that blocks stabilized water at the back of the structure by allowing rapid and tight spatial filling during injection with high cohesion The glycidylacrylate repair material can control the expansion rate, and the external stress also has the characteristic that the form of the material is not destroyed or separated, which can also be applied to vibrating induced structures that produce repetitive fatigue loads, and has an effective durability in saline, alkali, acid (chloric acid, sulfuric acid, nitric acid).