• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.778-784
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• 2008

In this paper, a chip antenna using multi-layer configuration for multi-band operation, such as GSM, DCS, pcs, WCDMA, and Mobile WiMAX for 2.3 GHz is proposed. This proposed antenna is a PIFA structure with multi-layer configuration fabricated on R04003 substrate(${\varepsilon}_r=3.4$) and its size is $22{\times}5.5{\times}4.0\;mm^3$. Multi-layer structure can effectively reduce the size of an antenna from a reuse of air-space and can achieve broad bandwidth due to decrement of parallel capacitances from the insertion air-gap to the middle layer. The proposed antenna has a broadband operation by the high order resonance modes and the resonance at the top layer. The measured bandwidths with over 45 % radiation efficiency are 80 MHz($880{\sim}960\;MHz$) at the lower band and 690 MHz($1,710{\sim}2,400\;MHz$) at the higher band.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.43-49
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• 2010

Direct printing technology is an attractive metallization method, which has become immerging as "Green technology" to the conventional photolithography, on account of low cost, simple process and environment-friendliness. In order to commercialize the printed electronics in industry, it is essential to evaluate the electrical properties of conductive circuits using direct printing technology. In this contribution, we focused on the electrical characteristics of inkjet-printed circuits. A Cu nanoink was inkjet-printed onto a Bisaleimide triazine(BT) substrate with parallel transmission line(PTL) and coplanar waveguide(CPW) type, then was sintered at $250^{\circ}C$ for 30 min. We calculated the resistivity of printed circuits through direct current resistance by the measurement of I-V curve: the resistivity was approximately 0.558 ${\mu}{\Omega}{\cdot}cm$ which is about 3.3 times that of bulk Cu. Cascade's probe system in the frequency range from 0 to 30 GHz were employed to measure the Scattering parameter(S-parameter) with or without a gap between the substrate and the probe station chuck. The result of measured S-parameter showed that all printed circuits had over 5 dB of return loss in the entire frequency range. In the curve of insertion loss, $S_{21}$, showed that the PTL type circuits had better transmission of radio frequency (RF) than CPW type.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1435-1444
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• 2008

In this paper, we designed a reduced height waveguide(WG) to microstrip mode converter with a short transition length. The mode converter is composed of a mode converter using E-plane probe and a modified impedance transformer. The mode converter was designed using a probe shorted to top of a 50 ohm ridge WG. The modified impedance transformer was designed to connect the mode converter to the reduced height WG. For wide bandwidth operation, the coupling of the two parts was tuned. The structure of the mode converter was optimized for low loss and wide bandwidth, and the optimized mode converter was fabricated. The performance of the mode converter was extracted using the thru and line S-parameters for back-to-back connections, and the connector loss was calibrated. The mode converter has a right angle structure and short transition length, 7.2 mm. The mode converter shows excellent performances; the insertion loss of 0.12 dB at 15 GHz, and the return loss above 10 dB for the full Ku-band.

• Advances in pediatric surgery
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• v.12 no.2
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• pp.192-201
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• 2006

There are considerable controversies in the management of congenital diaphragmatic hernia. By 1997, early operation, routine chest tube on the ipsilateral side and maintainingrespiratory alkalosis by hyperventilation were our principles (period I). With a transition period from 1998 to 1999, delayed operation with sufficient resuscitation, without routine chest tube, and permissive hypercapnia were adopted as our practice. High frequency oscillatory ventilation (HFOV) and nitric oxide (NO) were applied, if necessary, since year 2000(period II). Sixty-seven cases of neonatal Bochdalek hernia from 1989 to 2005 were reviewed retrospectively. There were 33 and 34 cases in period I and II, respectively. The neonatal survival rates were 60.6 % and 73.5 %, respectively, but the difference was not significant. In period I, prematurity, low birth weight, prenatal diagnosis, inborn, and associated anomalies were considered as the significant poor prognostic factors, all of which were converted to nonsignificant in period II. In summary, improved survival was not observed in later period. The factors considered to be significant for poor prognosis were converted to be nonsignificant after change of the management principle. Therefore, we recommend delayed operation after sufficient period of stabilization and the avoidance of the routine insertion of chest tube. The validity of NO and HFOV needs further investigation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.646-651
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• 2018

This paper reports that the electronic properties at a $P3HT/TiO_2$ interface associated with exciton dissociation and transport can be tailored by the insertion of a graphene quantum dot (GQD) layer. For donor/acceptor interface modification in an $ITO/TiO_2/P3HT/Al$ photovoltaic (PV) device, a continuous GQD film was prepared by a sonication treatment in solution that simplifies the conventional processes, including laser fragmentation and hydrothermal treatment, which limits a variety of component layers and involves low cost processing. The high conductivity and favorable energy alignment for exciton dissociation of the GQD layer increased the fill factor and short circuit current. The origin of the improved parameters is discussed in terms of the broad light absorption and enhanced interfacial carrier transport.

• The korean journal of orthodontics
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• v.30 no.6 s.83
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• pp.677-685
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• 2000

Anchorage plays an important role in orthodontic treatment. Because of limited anchorage Potential and acceptance problems of intra- or extraoral anchorage aids, endosseous implants have been suggested and used. However, clinicians have hesitated to use endosseous implants as orthodontic anchorage because of limited implantation space, high cost, and long waiting period for osseointegration. Titanium miniscrews and microscrews were introduced as orthodontic anchorage due to their many advantages such as ease of insertion and removal, low cost, immediate loading, and their ability to be placed in any area of the alveolar bone. In this study, a skeletal Class II Patient was treated with sliding mechanics using M.I.A.(micro-implant anchorage). The maxillary micro-implants provide anchorage for retraction of the upper anterior teeth. The mandibular micro-implants induced uprighting and intrusion of the lower molars. The upward and forward movement of the chin followed. This resulted in an increase of the SNB angle, and a decrease of the ANB angle. The micro-implants remained firm and stable throughout treatment. This new approach to the treatment of skeletal Class II malocclusion has the following characteristics . Independent of Patient cooperation. . Shorter treatment time due to the simultaneous retraction of the six anterior teeth . Early change of facial Profile motivating greater cooperation from patients These results indicate that the M.I.A. can be used as anchorage for orthodontic treatment. The use of M.I.A. with sliding mechanics in the treatment of skeletal Class II malocclusion increases the treatment simplicity and efficiency.

• Proceedings of the KSPS conference
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• 2000.07a
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• pp.86-87
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• 2000

In this paper, we discuss why two different surface forms appear in loanwords for English and German /${\int}$/ In Korean, a vowel is inserted into loanwords if a consonant cannot be properly syllabified. Therefore, /${\int}$/ in some positions of loanwords trigger vowel insertion. Interestingly, /${\int}$/s in the onset cluster of English and German words were borrowed in Korean as Iful with the inserted vowel [u] whereas If Is in the coda position of English and German words were borrowed as Ifil with the inserted vowel [i]. For example, 'shrimp' is adopted as [${\int}urimphi$] whereas 'rush' is adopted as [$ra{\int}i$]. In this paper, we attempt to find out the phonetic reason for the distribution of the surface forms of /${\int}$/. We assume that since the formant frequency of [i] is higher than that of [u], the peak frequency of /${\int}$/ with the surface form of [${\int}$i] in loanwords may be higher than that of /${\int}$/ with the surface form of [${\int}u$]. We also assume that duration may be another factor for the distribution of [${\int}i$] and [${\int}u$]. Since /${\int}$/ and /u/ use lip rounding whereas /i/ doesn't, the duration for [${\int}i$] might be longer than that of [${\int}u$]. German supports our assumption. /${\int}$/ in the onset cluster is longer than /${\int}$/ in the coda position. It also has higher peak frequency than that of /${\int}$/ in the coda position. In loanwords, ${\int}$ in the onset cluster is borrowed as [${\int}u$] as in Spiegel whereas /${\int}$/ in the coda position is borrowed as [${\int}i$] as in Bosch. English, however, does not support our assumption. Peak frequency of [${\int}$] depends on the preceding vowel, not on its position in the syllable structure. If the preceding vowel is front, then the peak freuency of the following of the following /${\int}$/ is high but if the preceding vowel is back, than the peak frequency of the following /${\int}$/ is low. The peak frequency of /${\int}$/ in the onset cluster seems to be in between. As we assumed, however, the duration of /${\int}$/ in the coda position is longer than of /${\int}$/ in the onset cluster. With the mixed results, we question whether Koreans really hear two different xounds for /${\int}$/ in English words. For the future experiment, we would like to perform the perception tet for /${\int}$/ in English words.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.259-264
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• 2001

It has been well known that the expression of S. typhimurium cadBA operon requires at least two extracellular signals: low pH and high concentration of lysine. To better understand the nature of pH-dependent and lysine dependent signal transduction, mutants were isolated in JF2238(cadA-lacZ) by Tn10 insertion, spontaneous mutagenesis, and EMS treatment. Two mutants were isolated from JF2238, expressed as a cadA-lacZ operon fusion in various growth conditions, and analyzed to have mutations in cadC, a gene encoding a function necessary for transcriptional activation of cadBA. One isolate (cadC6) conferred pH-independent and lysine-independent cadBA expression and the other(cadC4) showed pH-independent and lysine-dependent cadBA expression. cadR::Tn10 and cadR4 mutants were expressed in the absence of exogenously added lysine. They were also resistant to thiosine and complemented by lysP clone from E. coli. Thus, in the absence of exogenous lysine, cadR is a negative regulator of cadBA expression. Cadaverine, the product of lysine decarboxylation, was shown to inhibit expression of cadA-lacZ fusion in cad $C^+$ cell.

• Journal of Sensor Science and Technology
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• v.11 no.3
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• pp.163-170
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• 2002

This paper proposes a $10\;{\mu}m$ thick oxide air-bridge structure which can be used as a substrate for RF circuits. The structure was fabricated by anodic reaction, complex oxidation and micromachining technology using TMAH etching. High quality films were obtained by combining low temperature thermal oxidation ($500^{\circ}C$, 1 hr at $H_2O/O_2$) and rapid thermal oxidation (RTO) process ($1050^{\circ}C$, 2 min). This structure is mechanically stable because of thick oxide layer up to $10\;{\mu}m$ and is expected to solve the problem of high dielectric loss of silicon substrate in RF region. The properties of the transmission line formed on the oxidized porous silicon (OPS) air-bridge were investigated and compared with those of the transmission line formed on the OPS layers. The insertion loss of coplanar waveguide (CPW) on OPS air-bridge was (about 2dB) lower than that of CPW on OPS layers. Also, the return loss of CPW on OPS air-bridge was less than about -20 dB at measured frequency region for 2.2 mm. Therefore, this technology is very promising for extending the use of CMOS circuitry to higher RF frequencies.

• Journal of the Korean Society for Railway
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• v.18 no.3
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• pp.261-269
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• 2015

To overcome the weaknesses of viaduct bridges and the non-economic efficiency of underground LRT, the study of near-surface railway systems is in progress. To apply a box structure to the low depth transit, a connection joint to precast modules are very important when applying precast modular structures to replace temporary structures. In this study, wall to wall connections were applied in diverse cases such as rebar connections, guiding structures that were used to fit the verticality of precast walls during construction, and non-reinforcement structures used only for waterstop. Experimental performance verification was carried out for the bending, shear and splitting of the wall to wall connection. Precision of construction joints between wall to wall was identified as a factor that influenced the structural performance of the precast wall. A structure that can serve as a guide during the vertical insertion of a wall is confirmed for the most suitable case, but it will be necessary to modify this structure for detailed cases.