• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.497-502
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• 2005

In mobile phones of multimedia era, microspeakers of high quality sound are essential parts to generate human voice in speaker phone and MP3 song player. In this paper, two types of microspeakers, outer permanent magnet (PM) and combined PM type, are analyzed using electromagnetic, mechanical, acoustical and their coupling analysis. For performance comparison, voice coil diameter is chosen as a design parameter to change excitation position and magnet volume for both types. For combined PM type, sound pressure level (SPL) is improved due to increased PM volume compared to outer PM type. Also, with the decreased voice coil diameter for combined PM type, the 1st resonant mode of the diaphragm is more efficiently excited due to concentrative excitation, resulting in lower and broader frequency range. Therefore, it can be said that the combined PM type microspeakers are more advantageous for high performance microspeaker which are essential for multimedia era.

• 설비공학논문집
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• 제18권10호
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• pp.835-841
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• 2006

A $CO_2$ system using the two-stage compression cycle was tested by varying $1^{st}-2^{nd}$ compressor frequencies in the cooling mode. To improve the cooling performance of the two-stage compression $CO_2$ cycle, the following cycle options were applied: a basic cycle, a cycle with an intercooler, a cycle with an IHX (internal heat exchanger), and a cycle with an intercooler and IHX. The cycle with the intercooler-IHX showed the highest cooling capacity improvement among the cycle options at all compressor frequencies. The cycle with the intercooler, the cycle with the IHX, and the cycle with the intercooler-IHX improved the cooling COP by 7, 12, and 15%, respectively, over the basic $CO_2$ cycle when the compressor frequencies for the first and second compressors were 50 Hz and 30 Hz, respectively. In addition, the applications of the selected cycle options enhanced system reliability.

• 한국지형학회지
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• 제25권3호
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• pp.57-70
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• 2018

This study restores onshore paleo-shoreline records and establishes the nature and strain rate of neotectonism by investigating the existence and formative age of paleo-coastal sediments emerged around Sacheon-si in the Southern part of the Korean peninsula. As a result, paleo-sand bars representing 5m of the paleo-shoreline from high tide level are formed in Sacheon-si, and the formation age of these is confirmed as MIS 5c at approximately 100,000 year BP through rock surface luminescence dating to rounded gravels in paleo-sand bars. Although it is difficult to establish the uplift rate of crust precisely due to incomplete restoration of sea level records during the last interglacial stage, the uplift rate along the Southern coast of the peninsula was assumed approximately 0.72 lower than the Eastern coast during the late Quaternary in comparison to the 1st marine terrace along the Eastern coast.

• 한국군사과학기술학회지
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• 제25권6호
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• pp.596-605
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• 2022

In this study, analysis of dynamic characteristics and flight vibration was performed to unmanned aerial vehicles. The analysis model was supplemented by performing a dynamic characteristic test and a random vibration test using manufactured dummy aerial vehicle. For the dynamic characteristic test, a bungee cable was used to implement the free end boundary condition. Prior to the flight vibration test using a multiple electric shaker, a random vibration test was performed to predict the excitation force during the actual flight vibration test. It was judged that the actual test could be predicted more accurately by supplementing the analysis model from the test results. In addition, it was possible to determine the feasibility of the test by predicting the excitation force of the flight vibration test.

• 한국군사과학기술학회지
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• 제26권3호
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• pp.252-261
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• 2023

Analysis of dynamic characteristics and flight vibration test for unmanned aerial vehicles was studied by using dummy test body. The FEM model for dummy test body was supplemented by results of modal and random vibration test. The free end boundary condition to simulate flight environments was made by test setup using bungee cable. Prior to the flight vibration test using a dual electric vibration exciters, the test procedure to calculate quantitative vibration level was studied by using military specification. The actual test was successfully done by using the analysis and pretest results. From the analysis results, it was possible to determine the feasibility of the test by predicting the excitation force of the flight vibration test and to get the response of any point which could not be measured by the test. The results of this study will much contribute to the Test and Evaluation of unmanned aerial vehicles.

• Molecules and Cells
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• 제38권2호
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• pp.122-129
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• 2015

DBM-2198, a six-membered azasugar nucleotide (6-AZN)-containing phosphorothioate (P = S) oligonucleotide (AZPSON), was described in our previous publication [Lee et al. (2005)] with regard to its antiviral activity against a broad spectrum of HIV-1 variants. This report describes the mechanisms underlying the anti-HIV-1 properties of DBM-2198. The LTR-mediated reporter assay indicated that the anti-HIV-1 activity of DBM-2198 is attributed to an extracellular mode of action rather than intracellular sequence-specific antisense activity. Nevertheless, the antiviral properties of DBM-2198 and other AZPSONs were highly restricted to HIV-1. Unlike other P = S oligonucleotides, DBM-2198 caused no host cell activation upon administration to cultures. HIV-1 that was pre-incubated with DBM-2198 did not show any infectivity towards host cells whereas host cells pre-incubated with DBM-2198 remained susceptible to HIV-1 infection, suggesting that DBM-2198 acts on the virus particle rather than cell surface molecules in the inhibition of HIV-1 infection. Competition assays for binding to HIV-1 envelope protein with anti-gp120 and anti-V3 antibodies revealed that DBM-2198 acts on the viral attachment site of HIV-1 gp120, but not on the V3 region. This report provides a better understanding of the antiviral mechanism of DBM-2198 and may contribute to the development of a potential therapeutic drug against a broad spectrum of HIV-1 variants.

• 대한지리학회지
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• 제43권1호
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• pp.1-19
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• 2008

본 연구에서는 20세기 후반 관측자료를 분석하여 최근 한반도 겨울철 강수현상에 나타난 변화 양상과 그 원인을 밝히고, 21세기 후반 기후모델(GFDL 2.1) 자료를 바탕으로 미래의 겨울강수 변화추세를 예측해 보고자 한다. 61개 지점 관측자료를 분석한 결과 에 따르면, 지난 35년 동안$(1973/74\sim2006/07)$ 우리나라 겨울철($11\sim4$월) 총 강수량은 변화가 없었지만, 강설량은 약 4.3cm/10년의 비율로 감소하였다. 1980년대 후반 이후 강설일수가 감소하고, 강설강도가 약해지고, 강설계절의 길이가 줄어들면서 설수일율(전체 강수일 수에서 강설일이 차지하는 비율)도 낮아졌다. 이러한 패턴은 겨울철 강수형태가 점차 강설에서 강우의 형태로 바뀌어가고 있음을 보여준다. 이러한 우리나라 겨울철 강수 형태의 변화는 겨울철 양(+)의 북극진동(Arctic Oscillation)에 의해 한반도 주변의 겨울철 기압이 상승함에 따라 나타난 기온상승과 관련되어 있다. 1980년대 후반 이후의 동북아시아 지역의 기압 상승은 한반도 주변의 대기와 해양 온도를 차별적으로 상승시킴으로써 대기안정도 증가에 의한 눈구름 형성 감소와 관련된 대기-해양간 온도경도를 감소시켰다. 모델생산 미래$(2081\sim2100)$ 기후자료와 20세기 후반$(1981\sim2000)$ 기후자료 비교 분석 결과, 21세기 말에는 대기 중 온실기체의 양이 증가할수록 온난화가 강화되어 겨울철 강설기간이 더 짧아지고 강설불가능일이 더 증가할 것으로 예상된다.

• 한국전문물리치료학회지
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• 제10권2호
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• pp.45-59
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• 2003

The purpose of this study was to assess the effects of ultrasound on adjuvant-induced arthritis in rats. Adjuvant arthritis was induced in 26 female Sprauge-Dawley rats by the subcutaneous injection of a single dose of .1 mL of Complete Freund's Adjuvant (CFA) (1 mg of Mycobacterium Butyricum suspended in .1 $m{\ell}$ paraffin oil) into the right hind paw. After confirming inflammatory edema and arthritis in the paw 2 weeks later, the arthritic rats were divided into 3 groups, i.e., a control group, a pulsed ultrasound group (Group A), and a continuous ultrasound group (Group B) with 8 rats placed in each group. The rats in Group A were treated with pulsed ultrasound at 1 MHz frequency with .5 $W/cm^2$ intensity in 1 : 4 mode for 3 minutes. The rats in Group B were treated with continuous ultrasound at 1 MHz frequency with 2 $W/cm^2$ intensity in the continuous mode for 3 minutes. The ultrasound treatment was done in the left and right ankles for 2 weeks. Clinical, radiographic and histopathologic findings were then evaluated before and after treatment and yielded the following results. 1. No significant difference was present in body weight between the control group and the treated groups. 2. A statistically significant decrease in the edema of the paw was seen in the rats in Group A that was treated with pulsed ultrasound by 26~29 days after the treatment started (p<.05). 3. According to radiological examination, Group A showed the lowest score in arthritis scale which means it showed a tendency to suppress arthritic inflammation of the left and right hind paws. However, no statistically significant difference was present in the score between the control group, Group A and Group B. 4. According to histopathologic findings, the degree of infiltration by inflammatory cells and hypertrophy of the synovium were less in Group A compared with the control group and Group B. The results of the study show that rats that were treated with the pulsed ultrasound effectively suppressed adjuvant arthritis. However, more effort is needed to objectively prove the effectiveness of ultrasound by developing more sensitive testing methods that could quantitatively evaluate the treatment effects of acute rheumatoid arthritis and by trying out different ultrasound treatment methods.

• 한국ITS학회 논문지
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• 제8권3호
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• pp.52-63
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• 2009

최근 대도시의 경우 교통정보센터 및 ITS센터 등을 통하여 도시부 신호교차로를 운영 관리하고 있으며, 천안시도 ITS 1,2,3차 사업을 통하여 2007년 교통정보센터를 설립하여, 버스정보시스템, 교통정보 수집 및 제공 시스템, 주차정보시스템, 그리고 신신호제어시스템 등을 운영하고 있다. 천안시 신호운영체계의 경우, 주요 축별로 신호기를 그룹화 하여 연동화 운영중에 있으며, 교통량에 따라 실시간으로 주기와 현시가 변동되도록 운영하고 있다. 이와 같이 도시부 Network는 교통 대응식 (TRC; Traffic Responsive Control)운영모드의 사용으로 교통지체 및 축별 속도 등의 향상을 확인하였다. 그러나 인접도시를 연결하는 지방부 지역의 경우는 정통적인 고정식 운영을 사용함으로써 신호운영효율이 낮은 것으로 확인 되었다. 이에 지방부 독립신호교차로 형태의 신호교차로의 효율성 확대를 위해 감응식 운영모드의 사용 가능성을 검토하였다. 이를 위해 천안시 교통정보센터에서 운영하고 있는 신호교차로 중 천안 외곽지역의 신호교차로를 대상으로 감응식 신호제어를 운영하여, 이를 현재 운영중인 고정식 제어와 비교해 보았다. 그 결과 현장 운영시 감응식 신호운영제어가 고정식 신호운영에 비해 지체감소 효과가 월등하였으며, 비최적화 고정식, 최적화 고정식, 비최적화 감응식, 그리고 최적화 감응식의 네가지 Case의 시뮬레이션 지체비교에서는 최적화 고정식과 비최적화 및 최적화 감응식의 지체 차이는 통계적으로 차이가 없는 것으로 판명되었다. 이는 지방 중소도시의 경우, 도시부 이외의 지방부 성격을 갖는 신호교차로에서 있어서, 교통량 조사 등과 같은 부가적 노력 없이 신호교차로를 운영할 수 있는 감응식 신호제어 운영이 보다 효과적일 것으로 판단된다.

• 한국수산과학회지
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• 제21권6호
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• pp.323-330
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• 1988

한국 동해 연안역의 공간적인 수온변동 특성을 밝히기 위하여 23년간 평균된 월별 평균수온 자료를 이용하여 0m 층에서 300m층 까지 각각 수층별로 E.O.F 분석을 행하고, T-S diagram과 단면별 수온분포도를 작성하여 비교, 검토하였다. 대표적인 수온의 변동양상에 따라 표층 (0m\~50m), 차층 $(100m\~150m)$ 및 중층$(200\~300m)$으로 나누었다. 수온변동량의 1st mode값에 의한 각 수층별 수온변동 양상을 요약하면 다음과 간다. 표층에서의 수온은 주로 계절적인 변동양상을 보인다. $100\~150m$ 층의 수온은 난류수와 냉수간의 상호작용과 상층으로 부터의 열의 전달작용에 의하여 주로 변동됨을 알 수 있다. $200~300m$ 층에서의 수온변동은 주로 연안 저층냉수의 이류에 의하여 지배되는 것으로 사료된다. 본 연구는 1987년도 문교부 기초과학 육성연구비의 지원에 의하여 이루어 졌다.