• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.243-249
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• 2003

The head-on collision of two solitary waves are examined using a boundary element method. Attachment, detachment times and alplitudes and maximum run-up times and amplitudes are computed. Consolidation times show local minimum value if two waves are of equal amplitudes are colliding. Attachment times show local maximum value if the amplitudes of two waves are the same. The detachment time show local maximum if two wves are the same. The detachment amplitude show local minimum values if the amplitude e(=a/h) is greater than 0.3.

• International Journal of Automotive Technology
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• v.8 no.4
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• pp.521-531
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• 2007

Measurement of the vibration transmitted through rotating shafts such as half shafts in vehicles is of interest in applications such as noise transfer analysis and the study of operating deflections. Vibration signals transmitted through a rotating shaft usually include six degree-of-freedom components, thus making the measurement of vibration a challenging task. In the present work, a new measurement method is presented, one that resolves the minimum of only two one-axis accelerometer signals into all components of vibration with reasonable accuracy. The method utilizes the Dopplerized signals obtained from accelerometers attached to a rotating shaft and a Void-Kalman order tracking filter to decompose signals into orders of different vibration components. The new method proposed in the present work is verified by simulated run-up test data and applied to an experimentally obtained data set.

• Journal of KSNVE
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• v.9 no.4
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• pp.761-768
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• 1999

This paper presents an NVH test of Automotive power steering system performed at a half-car Test-rig. The test was done for neutral and full turn(or relief) conditions in steering wheel at a fixed rpm first, then followed by the same conditions for the rpm run-up. The sound intensity measurement verified the results from the frequency and order analysis, especially about the identification of major noise sources and their dominant frequencies. The results from thie study can be utilized in the system noise tuning when a new steering component is installed. In particular, the noise and vibration reduction at the relief condition will be accomplished through the knowledge obtained from this study and from the on-going research on the hose tuning techniques usign silencers and tuning cable inserted in the pressure hose.

• International Journal of Automotive Technology
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• v.1 no.2
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• pp.79-87
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• 2000

Analytical approach was followed in this work under both the steady state and transient operating conditions to find optimum boundary conditions, where the optically accessible quartz engine can run safely without breaking. Temperature and stress distribution was predicted by FEM analysis. In order to validate thermal boundary condition, model reliability and constraint, outside cylinder temperature was measured and previous study was also followed up numerically. To reduce thermal stress level, three types of outside cooling (natural, moderate forced and intensive forced convection) were considered. Effects of clamping force and combustion pressure were conducted to investigate mechanical stress level. Cylinder thickness, was changed to fine the optimum cylinder thickness. The versatile results achieved from this work can be basic indication, which is capable of causing a sudden quartz cylinder breaking during fired operation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.336-340
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• 2014

The noise and vibration have been evaluated by using the finite element model in the vehicle developing stage. The sound pressure of the vehicle compartment is predicted by the acoustic cavity model coupled with the body structure. In general, the structural model has been focused to study in the improvement of the noise. It is not easy to treat the structural model, instead the acoustic cavity model is relatively simple and aids in root cause analysis of vibro-acoustic issues. Therefore, the acoustic transfer function of the cavity is more efficient for finding out the main contribution parts of the vehicle booming noise. And examples about the run-up booming noise demonstrate the validity of the AFT analysis for improving the vibro-acoustic sensitivity.

• Journal of Engineering Education Research
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• v.19 no.2
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• pp.97-101
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• 2016

This paper examines the industry field training education model, analyze the operational status proposed improvement measures. Data were analyzed using a field training participating students participating industry last three years. On the other hand analysis field training participating students increased, industry participation has decreased. And most of the students took part in the seasonal short-term job training. In addition, it was difficult to analyze the employment status field training operations follow-up member. In this paper, a field training operations support system management models and practical training courses organized field trips how to improve. Field training operations support will be strengthened through the work associated with the company expanding participation model introduced and is expected to increase in the long-term practical training, students participate in field training system improvement. Run the job training Improvement in future research presented in this paper attempts to analyze the students' employment status and results of operations involved.

• KDI Journal of Economic Policy
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• v.34 no.1
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• pp.169-197
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• 2012

It is often argued that the parental leave should be extended in order to help employees achieve the balance of work and family life. However, one should be careful in designing the parental leave since there is a tradeoff between the continuity of employment after childbearing and the depreciation of human capital due to the time off the work. The paper investigates whether the parental leave payment introduced in Korea in 2001 helped women's take-up of the leave and employment after giving birth. The results are as follows. First, the increase in the payment indeed raised the female take-up of the leave. Second, women returned to labor market less often after giving birth in the short run, but the size of the effect tends to decrease in the long run. However, the negative effect on returning to the same workplace after the birth remains significant in the long run. Lastly, there is no evidence that the share of women of childbearing age at workplace changed due to the increase in the parental leave payment. Although there is a limitation in that the analysis is based only on the employment covered by the Employment Insurance, these findings imply that the increase in the parental leave payment may not be an effective policy tool for promoting female labor market participation. On the other hand, it should be noted that it is necessary to pay attention to child development as well as female employment as an objective in order to make an overall judgement on the parental leave policy.

• Journal of the Korean Institute of Educational Facilities
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• v.16 no.4
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• pp.61-70
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• 2009

From the mid-1990s, the discussion on alternative schools began in earnest, and with the increasing interests in them, Korean parents' association of alternative education, KPAAE was launched formally in November, 2008. Among the alternative schools in the nation, thirteen urban alternative schools were studied and analyzed. The result indicated that they are being run by individuals and civic organizations with no approval and the facilities and spatial organization of the schools are poor, which is thought to be mainly due to financial reasons as well as the schools' educational goal that puts emphasis on experiences leading to utilize outside local facilities. With this background, the results from the analysis of the facility status and the spatial organization of urban alternative schools led us to understand the followings: First, it showed that per capita average of area of the urban alternative school is approximately 11.995m$^2$, less than 14N, the standard area of institutional schools. Second, depending on the form of facilities, the space of other facilities is shared to make up for insufficient space, and is utilized to a small degree and for multi-purposes. Third, the space reflects the disposition of subject students, and is located in the area with convenient traffic for students' attending the schools conveniently. Fourth, specialized space is run on the basis of educational goals, and the exploring of career and the improving of sociality are pursued through internship programs associated with local facilities. Thus, it is desirable for the minimum per capita area of the urban alternative school to meet 14N, the standard area of the institutional schools in order that the urban alternative school may overcome the spatial limitation and the financial hardship stemming from the practically difficult constructing of new buildings and the small scale operation, and it may make flexible use of the space, and the students may live their lives smoothly. Also, it is thought that for the activating of the urban alternative schools, the plans for utilizing various facilities associated with local facilities should be considered.

• Atmosphere
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• v.26 no.1
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• pp.85-95
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• 2016

In this study, we investigated the variabilities of wind speed of 850 hPa and precipitable water over the East Asia region using the NCEP Final Analysis data from December 2001 to November 2011. A large variance of wind speed was observed in northern and eastern China during the winter period. During summer, the regions of the East China Sea, the South Sea of Japan and the East Sea show large variances in the wind speed caused by an extended North Pacific High and typhoon activities. The large variances in the wind speed in the regions are shown to be correlated with the inter-annual variability of precipitable water over the inland region of windward side of the Korean Peninsula. Based on the investigation, sensitivity tests to the domain size were performed using the WRF model version 3.6 for heavy precipitation events over the Korean Peninsula for 26 and 27 July 2011. Numerical experiments of different domain sizes were set up with 5 km horizontal and 50 levels vertical resolutions for the control and the first experimental run, and 9 km horizontal for the second experimental run. We found that the major rainfalls correspond to shortwave troughs with baroclinic structure over Northeast China and extended North Pacific High. The correlation analysis between the observation and experiments for 1-h precipitation indicated that the second experiment with the largest domain had the best performance with the correlation coefficient of 0.79 due to the synoptic-scale systems such as short-wave troughs and North Pacific High.

• YAKHAK HOEJI
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• v.48 no.3
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• pp.207-212
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• 2004

An analytic method was developed for the quantitation of $\Delta$$^{9}-$ tetrahydrocannabinol (THC) and 11-nor-9-carboxy THC (THC-COOH) in human hair. After hair samples were pulverized using Freezer Mill, deuterated internal standards were added and digested in 1 N NaOH at $100^{\circ}C$ water bath for 30 min. Digest solutions were extracted by 5 ml hexane：ethyl acetate (90：10) after acidification with acetic acid. The organic phase was evaporated under N 2 and derivatized by BSTFA (with 1% TMCS) at $85^{\circ}C$ for 45 min. The derivatized solution was separated on HP-5MS column ($30m{\times}0.25mm{\times}0.25mm$) and detected using EI-GC-MS with selective ion monitoring mode. The assay of calibration was ranged from 5 to 100 ng/50 mg hair ($r^2$＞0.99) for THC and THC-COOH. Within and between-run precision were calculated at 6, 30, 60 ng/50 mg hair with coefficients of variation less than 11%. Within and between run accuracies at the same concentrations were$\pm$14% and $\pm$30% of target for both analytes, respectively. Absolute and relative recovery at 10 and 100 ng were 60∼91％. The method was used to detect and quantify THC and THC-COOH in cannabis abuser's hairs (N = 16) and SRM (N=5, THC 1 ng/mg, NIST). We detected THC and THC-COOH in only one hair sample. In SRM, % accuracy was 93% (range 86∼103%) and precision (% CV) was 8.14. We began to set up a quantitative analysis of THC and THC-COOH using EI-GC-MS. Continuously, we need to modify and develop this method in order to apply for identification in cannanbis users' hair.