• 환경생물
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• 제40권4호
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• pp.477-496
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• 2022

During a survey of free-living marine nematodes of Korea, two new marine desmoscolecid nematodes belonging to subgenus Quadricoma Filipjev, 1922 were discovered. Tricoma (Q.) jejuensis sp. nov. and T.(Q.) unipapillata sp. nov. are described based on specimens obtained from washings of coarse sediments from eastern and southern coasts of Korea. Tricoma (Q.) jejuensis sp. nov. is characterized by having 33 quadricomoid body rings and inversion at main ring 23, pentagonal head with truncated anterior end, a pair of ocelli situated at main ring 6, somatic setae comprising of 8 pairs of subdorsal setae and 12 pairs of subventral setae, and relatively short spicules (42-46 ㎛ long). Tricoma (Q.) unipapillata sp. nov. is characterized by 44 quadricomoid body rings and inversion at main ring 32, somatic setae comprising of 7 pairs of subdorsal setae and 10 pairs of subventral setae, globular head truncated anterior end, relatively short and stumpy cephalic setae with cuticular flange, one single naked ventral median genital papillae situated on main ring 20, and spicules with a proximally marked capitulum. Detailed morphological descriptions and illustrations of these two new species are provided in this study.

• 기계저널
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• 제16권2호
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• pp.100-107
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• 1976

Stress analysis of tapered cylinder of reactor vessels is investigated by means of the intersection method. The tapered cylinder is approximated into three models-average cylinder, conical frustum, and ring. The results are compared with those of the finite element method program and an experiment. In this paper, the following results are obtained: (1) the best aproximation has been obtained by the ring model analysis: (2) the intersection analysis of the tapered cylinder by the ring model shows a sufficient accuracy for the stress analysis of reactor vessels.

• 대한의용생체공학회:의공학회지
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• 제32권4호
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• pp.305-311
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• 2011

For effective stimulation with tDCS, spatial focality of induced electrical field(EF) and current density(CD) is one of the important factors to be considered. Recently, there have been some studies to improve the spatial focality via different types of electrodes and their new configurations: some improvements using ring electrodes were reported over the conventional pad electrodes. However, most of these studies assumed isotropic conductivities in the head. In this work, we have investigated the effect of tissue anisotropy on the spatial focality of tDCS with the 4 + 1 ring electrode configuration via a 3-D high-resolution finite element(FE) head model with anisotropic conductivities in the skull and white matter. By examining the profiles of the induced EF from the head models with isotropic and anisotropic conductivities respectively, we found that the spatial focality of the induced EF significantly drops and get diffused due to tissue anisotropy. Our analysis suggests that it is critical to incorporate tissue anisotropy in the effective stimulation of the brain via tDCS.

• Bulletin of the Korean Chemical Society
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• 제25권9호
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• pp.1392-1396
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• 2004

The micellization of dodecylpyridinum chloride (DPC) assembled on aqueous gold nanoparticles has been studied as a function of concentration using Surface-Enhanced Raman Scattering (SERS). At the low concentration, the strong SERS band of the benzene ring moiety was observed at 1025 $cm^{-1}$, and assigned to “trigonal ring breathing”. According to high concentration of DPC, a new strong band was also appeared at 1012 $cm^{-1}$, which was assigned to “totally symmetry ring breathing”. The difference of two spectra seems to ascribe to the geometry of polar head group, i.e., pyridinium cation. These geometry exist flat-down at low concentration, whereas standing-up or tilted geometry at high concentration. The critical micelle concentration (CMC) was first obtained from the ratio of intensities of the two bands related to the benzene ring moiety by vibrational spectroscopy, and was about 28 mM. After the CMC, the benzene ring moiety in the micelle state was more restricted than in monomer state because there is no more change of intensities at 1012 $cm^{-1}$. In addition, the size of gold-assembled micelle was estimated using light scattering and it was about 328.3 nm.

• 전기전자학회논문지
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• 제25권4호
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• pp.721-727
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• 2021

본 논문은 게이티드 링 발진기를 이용한 UWB(Ultar-wideband) 임펄스 생성기 구조에 관한 내용이다. 기존 구조에서 필요로 하던 수 GHz의 발진기 및 PLL 회로를 게이티드 링 발진기로 대체하여 회로의 복잡도와 전력 낭비를 줄였다. 제안하는 방식은 링 발진기의 Head switch에 인가되는 Enable 신호의 길이를 조정함으로써 필요한 구간에만 발진기를 동작시키고 임펄스를 생성함으로써 출력 없이 쉬는 시간 동안 낭비되는 전력을 줄였다. 그리고 카운터를 통한 Pulse shaping 방법을 통해 사이드 로브의 발생을 억제하고 주파수 대역 변경을 위해 중심 주파수 변경시 대역폭 변화를 막을 수 있었다. 설계된 UWB 임펄스 생성기는 디지털 비트를 조정함으로써 6.0GHz에서 8.8GHz의 중심 주파수를 변경할 수 있으며 또한 사용 대역폭을 약 1.5GHz로 유지할 수 있음을 검증하였다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.523-526
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• 2006

A series of hydraulic and cavitation tests are performed in water environment in order to verify the hydraulic and cavitation performance of three types of LOX pumps. All the performances of the pumps are found to be satisfied with each design requirement. In the hydraulic tests, the head and efficiency are increased as the gap between floating ring seals and the impeller shoulder is decreased. In the cavitation tests, some pumps show decrease in the cavitation performance as the flowrate of the pump is decreased.

• 한국항공우주학회지
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• 제37권11호
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• pp.1140-1147
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• 2009

펌프공급방식 액체로켓엔진 가스발생기의 매니폴드를 대상으로, 연료 및 산화제의 유량 균일성을 파악하기 위하여 유동해석을 수행하였다. 3가지의 연료링과 3가지의 분사기 헤드 형상에 대하여 유동해석을 수행함으로써, 유량균일성을 검토하였다. 이를 통해 최적의 유량균일성을 가지는 연료링과 분사기 헤드의 형상을 결정하였다. 또한 분사기 출구에서의 혼합비 분포를 유동해석 결과로부터 도출하였다. 이를 통하여, 연료와 산화제 모두 유량균일성이 우수한 형상을 결정할 수 있었다.

• 대한두경부종양학회지
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• 제23권2호
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• pp.174-177
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• 2007

Mucosa-Associated Lymphoid Tissue(MALT) lymphoma is the most common extranodal B cell lymphoma among peripheral one. Although palatine tonsil is common origin among Waldeyer's ring, there is no presented case in Korea. This lymphoma is known to be less invasive than other subtype of low grade B cell Non-Hodgkin lymphoma. Because MALT lymphoma has a tendency of localizing one area for a long time, there are many cases treated by local treatment like radiotherapy, or local excision and radiotherapy. We report a case of MALT lymphoma originated from left tonsil.

• 소성∙가공
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• 제14권6호
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• pp.565-569
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• 2005

Reactor Vessel is one of the most important structural parts of nuclear power plant. It is manufactured by various steel forgings such as shell, head and transition ring. Head forgings have been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the open die forging process and manufacturing experience of large head forgings which can be used for the reactor vessel of 1,000MW nuclear power plant.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 제10회 단조 심포지엄
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• pp.131-139
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• 2005

Reactor Vessel is one of the most important structural part of nuclear power plant. It is manufactured by various steel forgings such as shell, head and transition ring. Head forgings has been made by open die forging process. After steel melting and ingot making, open die forging has been carried out to get a good quality which means high soundness and homogeniety of the steel forgings by using high capacity hydraulic press. This paper introduced the development trend of the open die forging process and manufacturing experience of large head forgings which canl be used for the reactor vessel of nuclear power plant.