• Korean Journal of Head & Neck Oncology
• /
• v.26 no.1
• /
• pp.37-40
• /
• 2010

Ectopic hamartomatous thymoma is a rare benign tumor of the lower neck occurring in the male adult predominantly. The origin of this tumor has been debated, but it is now believed to arise from remnants of the cervical sinus of His from early development. They are composed of epithelial, adipocytic, and spindle cells in variable amounts. Recognition of ectopic harmatomatous thymoma is important and needs to be differentiated from high-grade sarcomas such as synovial sarcoma or glandular malignant peripheral nerve sheath tumor. We here report on a case of ectopic hamartomatous thymoma arising in the left lateral neck of 33-year-old male patient.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.1
• /
• pp.384-389
• /
• 2011

This article presents an ultra broadband resistive power divider circuit for smart grid applications. Since the future smart grid system is expected to deploy high speed power line communication, the frequency response of the resitive power divider circuit is naturally of significance. Employing a thin film technology, the resistive power divider was designed, measured, and fabricated. For the circuit design, the conductor-backed coplanar waveguide line was firstly designed and measured. The 3 dB cutoff frequency was 72 GHz and S11 remains <-20 dB upto 70 GHz. The fabricated resistive power divider shows the 3 dB cutoff frequency of 50 GHz. It was experimentally verified that the resistive power divider circuit shows the insertion loss of 6 dB for high-speed input signal (40 Gb/s).

• Membrane Journal
• /
• v.11 no.2
• /
• pp.74-82
• /
• 2001

By using a phenomenological approach, model equations incorporating the resistance-in¬series concept were established to evaluate quantitatively concentration polarization in the boundary layer in feed adjacent to the membrane surface in the vapor permeation and separation of volatile organic compounds (VOCS)/$N_2$ mixture through po]y(dimethylsiloxane) (PDMS) membrane. The vapor permeations of various VOCS/$N_2$ mixtures through PDMS membrane were carried out at various feed flow rates. Chlorinated hydrocarbons, such as, methylene chloride, chlorofonn, 1,2-clichloroethane and 1,1,2-trichloroethane were used as organic vapor. By fitting the model equations to the experimental penneation data. the model parameters were detennined. respectively. Both the mass transfer coefficient of VOC across tbe boundary layer and concentration polarization modulus as a measure of the extent of concentration polarization were eitimated Quantitatively by the mooe1 equations with the determined model parameters. From the analysis on the detennined model parameters, the boundary layer resistance due to the concentration polarization of VOCs component was found to be more significant when the condensability of voe was greater. This study seeks to emphasize the importance of the boundary resistance on the vapor penneation of the vapor/gas mixtures with high permeability and high selectivity towards the minor component VOC.

• Membrane Journal
• /
• v.11 no.2
• /
• pp.83-88
• /
• 2001

A methodology for enhancing the bond strength of a coating layer with a support has been established in preparing low-pressure reverse osmosis mO) hollow fiber which would experience shear badly in flowing feed un it. Prior to coating process, the support membrane, ultrafiltratiun polysulfone(PS) hollow fibers was pretreated with a reaction solution containing glutaraldehyde (GAl which has a good affinity to the suppurt membrane material as well as a reactivity to some of the cunstituents of cuating layer subsequently formed on the support by interfacial polymerization. Therefore, the reactant GA distributed unifonnly over the support layer through the pretreatment could provide a strong adhesive bond between the coating layer and the support, sticking fast to the support membrane through physical bond and, at the same time, connecting its functional group with the coating laycr by chemical bonding. Due to the strong adhesive bond, the resulting hollow fiber membrane showed an excellent long-tcnn stability in pcnneation.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.19 no.6
• /
• pp.219-225
• /
• 2019

There is a problem with the existing method of selecting the difficulty levels of Hanja characters. Some Hanja characters selected by the existing methods are different from Sino-Korean words used in real life and it is impossible to know how many times the Hanja characters are used. To solve this problem, we measure the difficulty of Hanja characters using the multiple regression analysis with the frequency as the features. Based on the elementary textbooks, FWS and FHU are counted. A questionnaire is written using the two frequencies and stroke together to answer the appropriate timing of learning the Hanja characters and use them as target variables for regression. Use stepwise regression to select the appropriate features and perform multiple linear regression. The R² score of the model was 0.1105 and the RMSE was 0.1105.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.1
• /
• pp.79-87
• /
• 2015

In a gas engine, the exhaust and the engine cooling water are generated. The engine cooling water temperature is $100^{\circ}C$ and the exhaust temperature is $500^{\circ}C$. The amount of heat of engine cooling water is 43 kW and the amount of heat of exhaust is 21 kW. Eight different hybrid organic Rankine cycle (ORC) system configurations which considering different amount and temperature of waste heat are proposed for two gas engine tri-generation system and are thermodynamically analyzed. Simple system which concentrating two different waste heat on relatively low temperature engine cooling water shows highest thermal efficiency of 7.84% with pressure ratio of 3.67 and shaft power of 5.17 kW.

• Journal of IKEEE
• /
• v.14 no.3
• /
• pp.232-235
• /
• 2010

A 60GHz active phase shifter with 65nm CMOS is presented by replacing passive switches in switched-line type phase shifter with active ones. Active-switch phase shifter is composed of active-switch blocks and passive delay network blocks. The active-switch phase shifter design is compact compare with the conventional vector-sum phase shifter. Active-switch blocks are designed to accomplish required input and output impedances whose requirements are different whether the switch is on or off. And passive delay network blocks are composed of lumped L,C instead of normal microstrip line to reduce the size of the circuit. An 1-bit phase shifter is fabricated by TSMC 65nm CMOS technology and measurement results present -4dB average insertion loss and 120 degree phase shift at 65GHz.

• Proceedings of the KSR Conference
• /
• 2007.11a
• /
• pp.313-336
• /
• 2007

Unlike a conventional railway system, a high-speed rail system experiences various aerodynamic problems in tunnel sections. Trains running at a high speed in a small tunnel, when compared with the open field, face significant air pressure, resulting in reduced operating stability and fast change in pressure inside the tunnel. These phenomena further cause some unexpected problems such as the passengers onboard feeling an aural discomfort and an impulsive noise at the tunnel exit. To solve these problems, this paper introduces analysis of aerodynamic characteristics for determination of tunnel cross section. The optimum cross-section that satisfies the criteria of aural discomfort was reviewed through lots of numerical simulation analysis. Also, the pressure inside the passenger car of a train operating on Kyungbu HSR line was measured, and the pressure inside the tunnel and the micro-pressure waves at tunnel exit were measured at Hwashin 5 Tunnel. At the same time, a test of train operation model was performed and then the measurement results and test results were compared to verify that various parameters used as input conditions for the numerical simulations were appropriate.

• Korean Journal of Head & Neck Oncology
• /
• v.18 no.1
• /
• pp.56-59
• /
• 2002

Background and Objective: Even though major salivary gland tumor is a rare disease, the diversity of histopathologic characteristics makes treatment decisions difficult. The aim of this study is to analysis the clinical experience of our major salivary gland tumor and to suggest a guideline of treatment. Materials and Method: Sixty-eight major salivary gland tumors and tumor-like glandular enlargements treated at Sanggye Paik Hospital during the past seven years between June, 1995 and January, 2002 are analyzed for histopathologic diagnosis, treatment modality, clinical manifestation, local control, and treatment-related morbidity, recurrence rate, retrospectively. Results: In twenty-eight patients the swellings were diagnosed as non-tumorous condition. The clinical features, diagnostic and surgical management of fourty salivary neoplasms involving the parotid and submandibular glands are correlated with their histological features. Conclusion: We have concluded that salivary gland neoplasms are needed multimodal treatment, because of their highly variable biologic behavior in each tumor type. Thirty-four cases were benign and six cases were malignant. Most of benign cases were pleomorphic adenoma and they showed wide age-distribution. In six malignant cases, there were acinic cell carcinoma, adenocarcinoma, carcinoma ex-plemorphic adenoma, myoepithelioma, and adenoid cystic carcinoma.

• Journal of Korean Society of Steel Construction
• /
• v.23 no.5
• /
• pp.547-555
• /
• 2011

An unstiffened top and seat angle connection is a type of partially restrained connection that is suitable for low- and medium-rise steel buildings. The plastic moment resisting capacity of such connection is needed in practical design, in addition to the accurate prediction of the initial rotational stiffness. Therefore, most of the studies conducted for the mentioned connections were performed to predict the initial stiffness and the plastic moment resisting capacity with varying geometric properties. The main parameters of such experimental tests were the thickness and high-strength bolt gauge distance of AISC LRFD-type A top and seat angle connections. Based on the test results, the analytical model was also proposed in this study. The applicability of the proposed model was verified by comparing the test results from this study with those of other studies.