• 한국광학회:학술대회논문집
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• 한국광학회 2003년도 제14회 정기총회 및 03년 동계학술발표회
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• pp.204-205
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• 2003

미량기체의 흡수스펙트럼을 높은 감도로 측정하는 공동 광자감쇠 분광법(cavity ringdown spectroscopy； CRDS)을 나노초 레이저 펄스의 차주파수 생성(difference-frequency generation； DFG)을 광원으로 이용하여 파장 3 ~ 4 $\mu\textrm{m}$ 영역에서 구현하였다. CRDS는 고반사율 거울로 이루어진 광학적 공동에 단일 파장의 빛을 가두었다가 그 에너지의 시간적 감소율을 측정하여 공동 속 기체의 흡수율을 알아내는 방법이다. (중략)

• 산업공학
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• 제18권3호
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• pp.333-342
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• 2005

In this paper, we propose an efficient forecasting methodology of the mid and long-term frequency demand in Korea. The methodology consists of the following three steps: classification of basic service group, calculation of effective traffic, and frequency forecasting. Based on the previous studies, we classify the services into wide area mobile, short range radio, fixed wireless access and digital video broadcasting in the step of the classification of basic service group. For the calculation of effective traffic, we use the measures of erlang and bps. The step of the calculation of effective traffic classifies the user and basic application, and evaluates the effective traffic. Finally, in the step of frequency forecasting, different methodology will be proposed for each service group and its applications are presented.

• 한국음향학회지
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• 제34권6호
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• pp.411-422
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• 2015

본 논문은 "천해 지질환경과 음파전달환경과 상호 연계 연구"를 목적으로 한국해양과학기술원과 한양대학교가 2013년 4 ~ 5월에 경기만 태안반도 서쪽에 위치한 천해환경에서 공동으로 수행한 지질환경 조사 및 수중음향 실험에 대한 개요를 기술하였다. 실험지역은 강한 조류와 천해의 지형학적 특성에 의해 다양한 종류의 퇴적상과 베드폼이 형성되는 해역이다. 집중적인 지질환경 특성 조사를 위해 다중음향측심기, 천부지층탐사기, 중천부지층탐사기, 그랩을 이용하여 조사해역의 지질환경 특성을 파악하였으며, 저주파수, 중주파수 대역의 음원과 수직선배열청음기를 이용하여 주파수 200 ~ 16,000 Hz 대역에서 1) 저주파수 음파전달, 2) 중주파수 해저면 반사손실, 3) 주변소음의 공간 코히런스 분석, 4) 중주파수 해저면 후방산란에 대한 연구 주제로 해상실험이 수행되었다. 본 논문에서는 연구지역에서 음향실험을 실시한 동기, 음향실험 방법론과 측정된 지질자료를 기반으로 음향자료 해석과, 실험기간 동안 측정된 지질환경, 기상 해양물리 자료를 요약 정리하여 기술하였다.

• Ocean Systems Engineering
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• 제13권1호
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• pp.57-77
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• 2023

In the present study, the total hydrodynamic pressure exerted by the fluid on walls of rectangular tanks due to horizontal excitations of different frequencies, is investigated by pressure based finite element method. Fluid within the tanks is invisid, compressible and its motion is considered to be irrotational and it is simulated by two dimensional eight-node isoparametric. The walls of the tanks are assumed to be rigid. The total hydrodynamic pressure increases with the increase of exciting frequency and has maximum value when the exciting frequency is equal to the fundamental frequency. However, the hydrodynamic pressure has decreasing trend for the frequency greater than the fundamental frequency. Hydrodynamic pressure at the free surface is independent to the height of fluid. However, the pressure at base and mid height of vertical wall depends on height of fluid. At these two locations, the hydrodynamic pressure decreases with the increase of fluid depth. The depth of undisturbed fluid near the base increases with the increase of depth of fluid when it is excited with fundamental frequency of fluid. The sloshing of fluid with in the tank increases with the increase of exciting frequency and has maximum value when the exciting frequency is equal to the fundamental frequency of liquid. However, this vertical displacement is quite less when the exciting frequency is greater than the fundamental frequency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.175-176
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• 2014

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.672-673
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• 2012

• 대한지역사회영양학회지
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• 제25권4호
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• pp.291-302
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• 2020

Objectives: This study investigated the current use of university foodservice among Chinese international students in Korea, focusing on the relationship between the frequency of university foodservice use and their dietary life. Methods: An online survey was conducted on 452 Chinese international students from February 6 to 12, 2020. The respondents were classified into "the Low-frequency group" (< one time/week; n=144), "the Mid-frequency group" (one-two times/week; n=133), and "the High-frequency group" (≥ three times/week; n=175) according to their frequency of using university foodservice. The dietary life was compared among the three groups. Binominal logistic regression models were constructed to determine the associations between the frequency of university foodservice use and the changes in dietary life. Results: More than 2/3 (68.1%) of the respondents used the university foodservice at least once per week. Chinese international students who were males and Han Chinese people, lived on campus, had stayed longer in Korea, and had no cooking facilities tended to use the university foodservice more often. The level of satisfaction with the university foodservice was not high (3.52 out of 5-points). Only 20% ate meals three times per day, and only 22% ate breakfast almost every day. The frequencies of overeating and skipping meals increased after studying in Korea. The frequency of university foodservice use, along with the length of residence in Korea, was associated with these negative changes in dietary life. Overeating (OR=2.11) and skipping meals (OR=1.79) were more likely to increase after studying in Korea in the Mid-frequency group than in the High-frequency group. Conclusions: The frequency of university foodservice use was associated with the dietary life of Chinese international students in Korea. A high frequency (i.e. ≥ three times/week) of using university foodservice may positively affect the dietary life of Chinese international students in Korea.

• 간호행정학회지
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• 제3권1호
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• pp.5-15
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• 1997

Today's rapidly changing healthcare environment and increasingly professional nursing practice indicate that identifying leadership characteristic of nursing leaders and executives is a vital importance in today' s time and also mandate innovative leadership for nursing service. Therefore, the purpose of this study is to examined the transformational, transactional leadership styles of the Nurse Administrators. The sample consisted of sixteen mid-level nurse administrators, fifty head nurses of 5 General Hospital. Data for this study was collected from Sep. 20 to 29 by Bass' MLQ Questionnaire. The data was analyzed by frequency, percentage, one-way ANOVA. Major findings are as follows : Appropriate one-way ANOVA tests revealed that the differences for transformational and transactional leadership styles of nurse executives, mid-level nurse administrators as perceived by their immediate subordinates were statistically significant(P<.05). The scores of transformational and contingent reward behaviors were declined of the mid-level nurse administrators. The transactional scores of nurse administrators were lower than transformational ones, which is a desirable findings. The result of this study, the mid-level nurses administrators were perceived as the highest transformational leader by their subordinates. The nurse executives received the lower transformational leadership scores than mid-leval administrators. These results were opposit to the previous studies. Leader can aspire to these qualities of transformational leadership, building on the more traditional transactional dimensions. We can think that transformational leadership suggests a direction for developing a creative and rewarding approach to the leadership of professionalnursing practice environments. More research on transformational qualities in nursing service and controlled designs would be desirable for nursing service administration.

• 한국전자파학회논문지
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• 제15권6호
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• pp.619-626
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• 2004

채널 간격이 100 ㎓로 일정하고 채널 비트율이 40 Gbps인 16-채널 WDM 시스템에 MSSI(Mid-Span Spectral Inversion) 기법을 적용한 경우의 4-광파 혼합(FWM: Four-Wave Mixing)에 의해 왜곡된 채널 신호의 보상 특성을 살펴보았다. MSSl를 통한 광대역 보상을 위해 광 위상 공액기(OPC: Optical Phase Conjugator)의 비선형 매질로 HNL-DSF(Highly-Nonlinear Dispersion Shifted Fiber)를 사용하였다. 우선 MSSI 기법을 이용하면 FWM에 의한 채널 간섭의 영향을 모든 채널에 걸쳐 특정 입력 전력 범위 내에서 비슷한 특성으로 줄일 수 있다는 것을 확인할 수 있었다. 그러나 OPC에 의해 생성되는 공액파 전력이 입력 신호파 전력에 비해 작은 장파장 채널들은 광섬유의 분산 계수가 커질수록 보상의 정도가 줄어드는 것도 알 수 있었다. 즉 분산 계수가 비교적 적은 광섬유를 통해 채널 간격이 일정한 WDM 채널들을 특정 전력 이내에서 양호한 품질로 전송하는데 HNL-DSF를 이용한 MSSI 보상 기법이 효과적이라는 것을 확인할 수 있었다.

• 한국전자통신학회논문지
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• 제15권3호
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• pp.527-532
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• 2020

본 논문에서는 개인인증 시 활용 가능한 EEG 신호의 주파수 대역을 확인하기 위하여 뇌파 측정을 통해 분석한 결과를 제시하였다. 시각 과제의 유무에 따라 개안 상태와 폐안 상태로 구분하여 뇌파를 측정하였으며, 이를 델타파, 세타파, 알파파, SMR파, 중간베타파, 베타파 및 감마파의 7종류의 주파수 대역으로 나누어 시간에 따른 파워의 변동이 가장 작은 주파수 대역을 관찰하였다. 본 논문의 결과에서는 개안 상태와 폐안 상태에서는 유의한 차이가 나타나지 않았으나, 인간의 집중과 관련한 SMR파 및 중간베타파가 시간에 따른 파워의 변동이 가장 작게 관찰되었기에 재현성이 높은 주파수 대역인 것으로 나타났다.