• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.10 no.1
• /
• pp.1-11
• /
• 2012

The equation of the step-drawdown test "$s_w=BQ+CQ^p$" written by Rorabaugh (1953) is suitable for drawdown increased non-linearly in the fractured rocks. It was found that value of root mean square error (RMSE) between observed and calculated drawdowns was very low. The calculated $C$ (well head loss coefficient) and $P$ (well head loss exponent) value of well head losses ($CQ^p$) ranged $3.689{\times}10^{-19}{\sim}5.825{\times}10^{-7}$ and 3.459~8.290, respectively. It appeared that the deeper depth in pumping well the larger drawdowns due to pumping rate increase. The well head loss in the fractured rocks, unlike that in porous media, is affected by properties of fractures (fractures of aperture, spacing, and connection) around pumping well. The $C$ and $P$ value in the well head loss is very important to interpret turbulence interval and properties of high or low permeability of fractured rock. As a result, regression analysis of $C$ and $P$ value in the well head losses identified the relationship of turbulence interval and hydraulic properties. The relationship between $C$ and $P$ value turned out very useful to interpret hydraulic properties of the fractured rocks.

• The Research Journal of the Costume Culture
• /
• v.12 no.6 s.53
• /
• pp.1021-1030
• /
• 2004

The purpose of this study was to develop and make the head form by setting the region of the head for detailed measurement of the head to make the type of closely fit hat and typifying the head form of Korean women's with each region of the head based on the measurements of each region of the head according characteristics. A total of 285 Korean women's in the age group of 18 to 35 years old. It were measured through the direct measurement method by selecting 67 measurement items. As a result of the findings obtained from cluster analysis could be classified into 3 type. Type 1($46\%$) is U-shaped form, that is high in head height on sides and circumference is smallest, whose facial region and occiput is flattest of three types. Type 2($22.4\%$) is inverted triangle form, that is flat in head ridge, low in head height on sides and wide in the frontal width. Type 3($31.6\%$) is oval form, that is largest in size, has the projected occiput and is of three-dimensional form.

• Korean Journal of Head & Neck Oncology
• /
• v.33 no.2
• /
• pp.101-105
• /
• 2017

Mammary analogue secretory carcinoma (MASC) of the salivary gland is a newly classified pathologic entity since 2010. Prior to its recognition, MASC was diagnosed as low-grade cystadenocarcinoma, acinic cell carcinoma, and mucoepidermoid carcinoma. MASC shares common histological and genetic characteristics with secretory carcinoma of the breast and has a distinct feature of the ETV6-NTRK3 fusion gene. Treatment of MASC in salivary gland is mainly wide surgical resection of the tumor. Prognosis of MASC is similar to other low-grade salivary gland carcinomas. Herein, we report a case of MASC developed in a parotid gland with a review of the literature.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.18 no.9
• /
• pp.905-912
• /
• 2008

Notion sickness is well known to be caused by long time exposure to the very low frequency motion in the multiple axes of human body Since the vestibular system for the perception of low frequency motion is located in the head, accurate measurement of 6 degree of freedom head motion is of great importance. In this study, the measurement system consisting of a safety helmet and 9 translational accelerometers was constructed for the estimation of 3 translational and 3 rotational motions of human head. Since estimation errors of 3 rotational components can be significantly magnified even by small offset of the sensitivity axis from the geometric center of an accelerometer, accurate measurement of sensitivity axis must be preceded. The method for accurate estimation of the offset was proposed, and the effect of offset on the estimation of angular acceleration was investigated.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.1
• /
• pp.35-42
• /
• 2012

This paper is about the implementation of low cost WiMAX remote radio head system with Ethernet instead of optical link. We deployed a simplified frame structure on the data frames transmitted between a basestation and remote radio heads in order to maximize Ethernet link utilization which shows relatively lower maximum throughput compared to that of optical links. In addition, a synchronization mechanism was applied on a basestation and remote radio heads placed on remote sites in order for simultaneous data transmission and reception in all remote radio heads which are essential for proper communication with terminals. These schemes are implemented with FPGA. The results of experiment with a WiMAX Femtocell show that our remote radio head systems efficiently deliver radio frames with proper timing.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.25 no.4
• /
• pp.301-306
• /
• 2016

High speed polishing can kinematically increase the polishing removal rate by using the conventional Preston equation, especially for hard substrates such as sapphire or diamond. However, high speed effects should be clarified beforehand considering the lubrication state and process parameter variations. In this paper, we developed a polishing experimental method and apparatus to determine the lubrication state by measuring the real time friction coefficient using two load cells. Through experiments, we obtained a boundary lubrication state above 0.35 of the friction coefficient by using low table speed and high polishing load, indicating a synchronized stable behavior in polishing head rotation. However, larger Stribeck indexes by a high speed above 200 rpm can generate a hydrodynamic lubrication state below 0.25 of the low friction coefficient. This causes the polishing head rotation to stop. A forced and synchronized head rotation is required for high speed polishing.

• Korean Journal of Head & Neck Oncology
• /
• v.37 no.2
• /
• pp.61-65
• /
• 2021

Epithelial-myoepithelial carcinoma is rare, low-grade malignant neoplasm that compromises approximately 1% of all salivary gland neoplasms. We reported a 68-year-old woman with epithelial-myoepithelial carcinoma in the parotid gland. We analyzed demographic and clinicopathological characteristics of salivary gland epithelial-myoepithelial carcinoma which has been reported in 33 cases in Korea from 1992 to 2017, and compared this result to overseas retrospective cohort studies. There was no significance in terms of mean age at diagnosis, the predominance of females, low frequency in regional lymph nodes, and distant metastasis between the two groups. However, T classification and AJCC stage at diagnosis in domestic cases are more advanced than those of overseas cases. Although the recurrence rate in domestic cases has been reported lower than that of overseas, further study may be needed considering that the follow-up period after treatment is short in domestic cases.

• Journal of the Korean Society of Radiology
• /
• v.17 no.7
• /
• pp.1133-1138
• /
• 2023

This study analyzed the relationship between image parameters and specific absorption rate (SAR) in various sequence environments to optimize SAR. For this purpose, image parameters were adjusted for T2, T1, STIR, T1 FLAIR, and T2 FLAIR sequences in a 3.0T MRI, and the whole body (WB) SAR and head SAR calculated by the device were measured. Then, the SAR was evaluated by adjusting the number of images and the flip angle (FA) of the refocusing RF. As a result, SAR increased as the number of image increased in all sequences. T1 and T1 FLAIR had correlation coefficients (r) of 0.876, 0.876 (WB SAR, head SAR), 0.867, 0.867 (WB SAR, head SAR), respectively, and STIR had the highest correlation with 0.898 and 0.899 (WB SAR, head SAR). showed (p<0.05). When applied by increasing the refocusing FA, WB SAR and head SAR increased overall in all sequences. The T1 and T2 sequences showed high correlation with correlation coefficients (r) of 0.897, 0.898 (WB SAR, head SAR) and 0.914, 0.915 (WB SAR, head SAR), respectively, while the sequences to which the inversion recovery technique was applied had relatively low FA, showed less sensitivity to increase. Therefore, in a sequence with a relatively low TR, minimizing the number of image and applying the fast spin echo to reduce the refocusing FA in a sequence with a high duty cycle are effective in reducing SAR.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.9
• /
• pp.203-211
• /
• 1999

The research committee for automobile repairs (RCAR), an international body of insurance research centers, has adopted the typical low speed crash test based on an average damage level in crash accidents to estimate the damageability , repairability and safety. The characteristics of body acceleration and the probability of injury are investigated based on damaged components, accelerations of body and injured dummy to analyze damageability and the driver's safety under low speed crash environment. It is found from the experimental results that the probability of head and thorax injuries are very low comparing to the injury criteria of FMVSS No.208. Furthermore, it is suggested that the deployment of airbag may not be necessary at RCAR low speed frontal crash test.

• Korean Journal of Head & Neck Oncology
• /
• v.30 no.2
• /
• pp.87-89
• /
• 2014

Epidermal cysts in mouth floor are rare. There could be confusions in diagnosis due to location and low incidence. For diagnosis, imaging study and cytology are necessary. The treatment of choice is complete excision intraorally or externally and the recurrence is rare. Some authors prefer sclerotherapy, but the follow up is necessary for malignant change. We report two cases of epidermoid cyst in submental area excised externally with literature review.