• 한국전자파학회논문지
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• 제20권3호
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• pp.273-279
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• 2009

본 논문에서는 다이폴형 방사 패턴을 나타내며, 저자세를 갖는 안테나를 제안하였다. 제안된 안테나는 0.43 $\lambda_g$ 길이의 L형 슬롯 소자를 기본으로 하여 4개의 슬롯 소자 배열로 평면형 모노폴 안테나의 기저단이 정합 구성되었다. 제안된 안테나는 수평면 내에서 무지향성 방사 패턴을 나타내며, 브로드 사이드 방향에서는 영점을 갖는다. 설계에서 커패시턴스 소자로 동작되는 소형 모노폴 안테나를 4개의 L형 슬롯에 의하여 일부분이 제거되어진 접지 면과 결합시켰다. 그 결과 이들 구조들은 방사를 위한 LC 공진기로 동작하게 된다. 제안된 안테나의 실제 측정 결과, 임피던스 대역폭(VSWR$\leq$2)은 60 MHz(2.35$\sim$2.41 GHz)로 나타났으며, 동작 중심 주파수 2.38 GHz에서 최대 이득과 방사 효율은 각각 0.02 dBi, 56.7 %로 나타났다. 제안된 안테나는 무선 랜 액세스 포인트 시스템에 적용될 수 있을 것으로 사료된다.

• 한국전자통신학회논문지
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• 제14권3호
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• pp.461-466
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• 2019

본 논문에서는 일반적인 마이크로스트립 안테나의 이득을 넓히기 위해 많이 사용되는 적층형 구조에 이중 급전과 L형 인셋 급전 선로 매칭회로를 이용하여 이득 및 대역폭 특성을 개선하는 연구를 하였다. 제안된 구조는 주패치 안테나의 두 개의 방사 에지(edge)에 각각 L 모양의 인셋 급전회로를 갖는 급전 선로를 연결한 구조이다. 그리고 기생패치는 주패치 위에 적절한 거리를 두고 놓여 있는 구조이다. 주패치의 크기는 공진주파수가 목표로 하는 주파수 대역의 중심 주파수에 근접하도록 설계한다. 측정 결과 단일 급전보다 관심 있는 2.3~2.7GHz 대역에서 대역폭은 180MHz 이상 증가되었고 2.7Ghz에서 최대 2.5dBi의 이득 향상을 얻을 수 있었다.

• Journal of Gastric Cancer
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• 제23권4호
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• pp.561-573
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• 2023

Purpose: This study aimed to compare the long-term functional and patient-reported outcomes between intra-corporeal delta-shaped gastroduodenostomy and gastrojejunostomy after laparoscopic distal gastrectomy for gastric cancer. Materials and Methods: We retrospectively reviewed clinicopathological data from 616 patients who had undergone laparoscopic distal gastrectomy for stage I gastric cancer between January 2015 and September 2020. Among them, 232 patients who had undergone delta-shaped anastomosis and another 232 who had undergone Billroth II anastomosis were matched using propensity scores. Confounding variables included age, sex, body mass index, physical status classification, tumor location, and T classification. Postoperative complications, nutritional outcomes, endoscopic findings, and quality of life (QoL) were compared between the 2 groups. Results: No significant differences in postoperative complications or nutritional parameters between the two groups were observed. Annual endoscopic findings revealed more residual food and less bile reflux in the delta group (P<0.001) than in the Billroth II group. Changes of QoL were significantly different regarding emotional function, insomnia, diarrhea, reflux symptoms, and dry mouth (P=0.007, P=0.002, P=0.013, P=0.001, and P=0.03, respectively). Among them, the delta group had worse insomnia, reflux symptoms, and dry mouth within three months postoperatively. Conclusions: Long-term nutritional outcomes and QoL were comparable between the delta and Billroth II groups. However, more residual food and worse short-term QoL regarding insomnia, reflux symptoms, and dry mouth were observed in the delta group. Longer fasting time before endoscopic evaluation and short-term symptom management would have been helpful for the delta group.

• 한국군사과학기술학회지
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• 제21권5호
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• pp.563-571
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• 2018

In order to effectively protect a penetrator, the conically shaped protector was proposed and the protection capability was investigated. The collision and penetration of the penetrator with the protector were analyzed using dynamic finite element analysis. The post impact behaviors of the penetrator, i.e., flying velocity and the change of attitude angle, were monitored to investigate the protection capability. The flying velocity and the attitude angle are used to investigate the deviation and the penetration power respectively. The effect of rotation speed of the protector and the collision position on the protection capability is investigated in the viewpoint of deviation and attitude angle when penetrator colliding with our tank.

• Applied Microscopy
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• 제19권1호
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• pp.34-48
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• 1989

The oval shaped pericardial cells are clustered along the lateral sides of the heart and irregularly connected with the heart. The cells are bounded by a basement membrane. The basement membranes of the connected two peicardial cells are irregularly linked each other there-fore funnels are formed. The multiple invaginations of the cell membrane are observed and septate junctions develope at the part of enterance of the cell membrane. The coated pits are appeared in the inner side of the invaginated cell membrane. The coated vesicles, tubular and spherical shaped vesicle, Golgi complex containing high electron densed material in the cisternae and mitochondria are observed in the cytoplasm and lysosomes are remarkably well developed. The whirled membrane structures in the multiformed complex bounded by single membrane are linked with low electron densed granules and spherical shaped small granules having high electron density with $0.03{\mu}m$ in diameter are located between the whirled membrane in a row and gradually secretes the granules and then they produced the multilamellar body. The lysosomal regions of cytoplasm of pericardial cell are appeared negative reaction to the acid phosphatase and according to the results of the electrophoresis, lipoproteins having acid phosphatase activity are contained. The axon is contacted with the pericardial cells.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.293-296
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• 2005

This paper presents the design of linear and circular polarization baseball- shaped circular microstrip antenna (BCMA) with 3-dimensional structure using perturbation effect to reduce its size, which runs at 1.575GHz frequency bandwidth. As a result, the size of linear polarized antenna could be reduced up to 23.7% in patch diameter and 41.8% in its area. Linear polarized antenna has -26.04dB of return loss, 69MHz(4.38%) of -l0dB bandwidth, 4.51dBd of gain, and its -3dB beamwidth are 99$^{\circ}$ in E-plane, 83$^{\circ}$ in H-plane. Circular polarized antenna has -17.43dB of return loss, 113.7MHz(7.2%) of -l0dB bandwidth, 2dBd of gain, 2dB of axial ratio and its -3dB beamwidth are 87$^{\circ}$, 86$^{\circ}$ x-axis polarized, 80$^{\circ}$, 84$^{\circ}$ y-axis polarized. It has 82mm of diameter, which is 28.5% of linear polarized CMPA. Therefore, in this paper we verified that baseball-shaped 3-dimensional structure of circular microstrip patch antenna applied with perturbation effect is appropriate for miniaturization.

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.295-300
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• 2002

The construction of the T-shaped post-column flow cell has been changed to enhance the practicability as a UV-visible absorbance detector for capillary electrophoresis. In this new design, a rectangular cube-shaped inner structure is employed, which completely fits the outer rectangular tubing. This arrangement has greatly facilitated the fabrication of the T-cells. In addition, the volume for the auxiliary flow has been dramatically reduced down to 300 ${\mu}L$, and its volume flow rate is optimized at 4.2 ${\mu}L$/min. The short optical path length in the sheath flows (500 ${\mu}m$ on each side) minimizes background absorption, and thus enhances its performance in low-UV wavelengths. We have optimized the auxiliary flow rate at 50 ${\mu}m$/s, so that migration times are insensitive to the flow rate. This optimization has improved repeatabilities in migration times and peak heights. A double-beam detection scheme using a pair of photodiodes is employed to increase the signal-to-noise ratio.

• 한국통신학회논문지
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• 제18권8호
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• pp.1059-1068
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• 1993

임의 모양을 갖는 마이크로스트립 안테나의 해석에 역점을 두었다. 마이크로스트립 안테나의 가장 일반적이고 정확한 해석법은 주파수 영역에서 정의되는 전계적분방정식을 이용하는 것이다. 본 논문에서는 전계적분방정식을 수정한 MPIE(Mixed potential integral equation)를 이용하여 공간영역에서 해를 구하였다. 이 방법은 스칼라와 벡터 포텐셜과 관련된 Green함수를 다층매질 이론에 의해 계산하고 Sommerfeld 적분방정식에 의해 표현한다. 또한 적분방정식은 rooftop 부분기저함수를 이용한 모멘트법을 이용하여 해를 구하였다. 따라서 임의의 모양의 마이로스트립 안테나를 임의의 주파수와 임의의 기판상에서 해석할 수 있다. 구형 마이크로스트립 안테나와 L자형 마이크로스트립 안테나의 수치 결과를 실험치와 비 교하였다.

• ETRI Journal
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• 제34권5호
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• pp.674-683
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• 2012

We propose a slot antenna consisting of a rectangular slot on the ground plane, fed by a microstrip line with a rectangular-ring-shaped tuning stub that can be deployed in ultra-wideband (UWB) communication systems to avoid interference with wireless local area network (WLAN) communication. Our antenna can achieve a single band-notched property from the 5 GHz frequency to the 6 GHz frequency owing to a controllable band notch that uses L- and J-shaped parasitic elements. The antenna characteristics can be modified to tune the band-notched property (4 GHz to 5 GHz or 6 GHz to 7 GHz) and the bandwidth of the band notch (1 GHz to 2 GHz). Furthermore, the shifted notch with enhanced width of the band notch from 1 GHz to 1.5 GHz is described in this paper. The UWB slot antenna and L- and J-shaped parasitic elements also provide the band-rejection function for reference in the WiMAX (3.5 GHz) and WLAN (5 GHz to 6 GHz) regions of the spectrum. Experiment results evidence the return loss performance, radiation patterns, and antenna gains at different operational frequencies.

• Animal Systematics, Evolution and Diversity
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• 제31권4호
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• pp.277-283
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• 2015

Two pleurostomatid ciliates, Loxophyllum perihoplophorum Buddenbrock, 1920 and L. rostratum Cohn, 1866, were collected from the coastal waters of the East Sea, Korea. Their morphologies are described based on live observation and protargol staining, and morphometrics are provided. Loxophyllum perihoplophorum is characterized by the following features: 200-650 μm long in vivo; body slender leaf-shaped, flexible and contractile, with thin and wide extrusome-belted zone; 2 macronuclear nodules (Ma) and 1 micronucleus (Mi); 7-9 contractile vacuoles (CV) positioned along dorsal margin; extrusomes (Ex) evenly distributed along edge of entire body, with about 10 dorsal warts (Wa); 9-11 left (LSK) and 19-22 right somatic kineties (RSK), 4-5 furrows (Fu) on left side. Loxophyllum rostratum is about 100-130 μm long in vivo; body oblate leaf-shaped, contractile, convex ventral side and S-shaped dorsal side, beak-like anterior end; 2 Ma and 1 Mi; 1 CV terminally located; Ex distributed along edge of entire body, with about 9-10 dorsal Wa; 7-8 LSK and 15-19 RSK, ca. 5 Fu on left body side. In addition, sequences of small subunit ribosomal DNA were determined from these two Loxophyllum species and compared with the known Loxophyllum sequences.