• 한국실내디자인학회논문집
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• 제21호
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• pp.26-32
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• 1999

This study is intended to explore the tendency of interior design which have sustained the periodic changes throughout the history. After analysis of changes in interior design from 1920's early modernism to nowadays, the conclusion is as follows. In view of the human psychology, the main trend of consistent periodic changes is the revolutionary change of tension and relaxation, and the pursuit of such a change in design is rooted in the human basic need to get the vital energy through stimuli by giving and taking the variety in the public society.

• 천문학회보
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• 제44권1호
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• pp.85.3-85.3
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• 2019

Pulsating variable is a star whose luminosity changes through periodic pulsation. There are radiative and dynamical mechanisms hidden in periodic brightness changes, and the physical quantities related with the mechanisms are also expected to vary periodically. The purpose of this study is to investigate the periodic variations of the physical quantities of the ${\delta}$ Scuti type variable, V350 Peg by simultaneous photometry and spectroscopy. In this poster, we present preliminary results on apparent magnitude and radial velocity at the surface.

• Journal of Power Electronics
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• 제15권4호
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• pp.1085-1092
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• 2015

In this paper, the expressions of the estimated information of a single-phase enhanced phase-locked loop (EPLL), when input signal contains harmonics and a DC offset while the fundamental component takes step changes, are derived. The theoretical analysis results indicate that in the estimated information, the n^th-order harmonics cause n+1^th-order periodic ripples, and the DC offset causes a periodic ripple at the fundamental frequency. Step changes of the amplitude, phase angle and frequency of the fundamental component cause a transient periodic ripple at twice the frequency. These periodic ripples deteriorate the performance of the EPLL. A hybrid filter based EPLL (HF-EPLL) is proposed to eliminate these periodic ripples. A delay signal cancellation filter is set at the input of the EPLL to cancel the DC offset and even-order harmonics. A sliding Goertzel transform-based filter is introduced into the amplitude estimation loop and frequency estimation loop to eliminate the periodic ripples caused by the residual input odd-order harmonics and step change of the input fundamental component. The parameter design rules of the two filters are discussed in detail. Experimental waveforms of both the conventional EPLL and the proposed HF-EPLL are given and compared with each other to verify the theoretical analysis and advantages of the proposed HF-EPLL.

• 한국주거학회논문집
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• 제17권5호
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• pp.67-76
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• 2006

The purpose of this study was to explore the periodic changes of apartment supply between 1980 and 2001 in the City of Donghae. A survey was conducted with 82 apartment complexes that were built in during 21years. The data were itemized and specified by the unit house area, story, periodic and local apartment distribution. They were classified by five:(5) periods and analyzed by each apartment complexes for building characteristics. There were found that apartment housing were influenced by many primary factors such as demographics and a lot of the housing politics etc. The results of this study were as follows: 1) Apartment supply in the City of Donghae mass-produced from 1980 to 2001; Especially the forth period was supplied 5,999 households. 2) Between south area and north area was found a regional disparity. 3) The exclusive use $34{\sim}66m^{2}$ were continuously and centrally supplied according to the housing policy and practical demand. 4) For the types of story were variously found ; Especially the below 5 story apartment was continuously supplied.

• 한국지역지리학회지
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• 제6권3호
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• pp.1-36
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• 2000

구한말과 일제시기 동안 조선 후기의 유통구조는 근본적인 변화를 겪었는데, 한강 중류지역의 변화를 통해 그 변화 모습의 대강을 찾아볼 수 있었다. 구한말과 1900년대 초반 원거리 운송은 주로 한강 수운에 의해, 단거리 운송은 소와 사람에 의해 이루어졌다. 따라서 포구가 원거리 운송의 결절점으로서 물자 이출입의 통로 역할을 하였다. 1905년 경부선 철도의 개통과 1911년부터 대대적으로 벌어진 신작로 개설 및 우마차의 본격적인 사용은 한강 원거리 유통구조에 일대 혁신을 불러왔다. 이출부분에서 경부선 철도의 개통으로 현재의 이천시와 용인시 안성시의 행정적 경계가 경부선과 남한강 수운 영향권의 경계선으로 등장하였다. 이입부분에서는 경부선 철도의 개통으로 철도역과 관계되어 있는 안성장, 오산장, 수원장 등이 고차중심지로 새롭게 떠오르고, 우마차의 본격적인 사용으로 중 단거리 운송비가 1/4 정도로 절감됨에 따라 서울 한강변 포구와의 경쟁력이 급속히 강화되어 남한강 서쪽지역의 대부분까지 그 영향권을 확대한 것으로 보인다. 1927년 천장선(天長線)(천안${\sim}$장호원), 1932년 수려선(水驪線) 철도(鐵道)가 개통(開通)됨으로써 원거리 유통구조는 다시 한번 변화를 겪게 된다. 이들 노선의 개통으로 이출부분에서 여주 이천 남쪽 지역의 대부분을 철도가 장악함으로써 남한강 수운에 대한 결정적 타격을 입히게 되었다. 이입부분에서는 한강 중류지역으로부터 유입되던 물자가 경부선 철도역 장시들을 통하지 않고 직접 들어오게 됨에 따라 안성장, 오산장, 수원장의 한강 증류지역에 대한 고차중심지적 성격이 거의 사라지게 되었다. 양평 지역은 1930년대까지도 철도의 영향권 밖에 있었기 때문에 남한강 수운에 대한 의존도가 매우 높았던 것으로 보인다. 하지만 중앙선이 1939년 양평까지, 1942년 원주까지 개통됨에 따라 비슷한 변화가 나타났을 것으로 예상된다.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2004년도 춘계학술발표회논문집
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• pp.553-558
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• 2004

Periodic profiling by level is a conventional method for monitoring topographic changes in a specific part of tidal zone. Periodic aerial photographs are used for monitoring topographic change of broad tidal zone area. In this study, spot heights at interval of 50m on 5 profiling lines were leveled periodically for precise monitoring topographic change of tidal zone. For monitoring broad topographic change of tidal zone, aerial photographs were also taken by film camera loaded on pilotless helicopter periodically Periodic profiling shows the change of heights on the lines well. On the other hand, aerial photographs taken by film camera loaded on pilotless helicopter have some problems to detect topographic change of tidal zone precise. Because the scale and incline of the photographs were not same, it is hard to compare them. Therefore, for more precise monitoring of topographic changes in tidal zone, it is need to take aerial pictures with same scale and same incline.

• 한국동물학회지
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• 제20권2호
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• pp.67-76
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• 1977

The periodic changes of testis and \ulcorner션 epididymidis in Korean hibernating bats, the oriental discoloured bats (Vesportilio superans Thomas) and the Korean greater horseshoe bats (Rhinolophus ferrumequinum korak Kuroda) were studied in order to clarify the possibility of correlation between their histological findings and one of physiological facets, hibernation, and the results obtained were as follows: 1. The spermatogenic function of the oriental discoloured bats obtained in July and August was depressed although the spermatocytes showed a considerable cell proliferation. Few mature sperms were observed in the seminiferous tubules of the bat obtained in August. 2. The spermatogenic function of the Korean greater horeshoe bats obtained in September was not remalkable but a considerable number of sperms were stored in the excretory ducts which were characterized by existence of para-tubular spaces in the ductus epididymidis. 3. The spermatogenic epithelia of the Korean greater horseshoe bats obtained in December showed histologically atrophied figures. However, a vast number of sperm remained in extremely expaned luminae of the ductuc epididymidis which epithelial cells were maintained rectangular in shape. 4. These results suggest that there are periodic changes of the spermatogenic epithelia and the excretory ducts, and that those histological changes are closely related to their wintering.

• Structural Engineering and Mechanics
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• 제16권1호
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• pp.17-34
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• 2003

This paper presents a damage assessment procedure applied to periodic spring mass systems using an eigenvalue sensitivity-based method. The damage is directly related to the stiffness reduction of the damage element. The natural frequencies of periodic structures with one single disorder are found by adopting the transfer matrix approach, consequently, the first order approximation of the natural frequencies with respect to the disordered stiffness in different elements is used to form the sensitivity matrix. The analysis shows that the sensitivity of natural frequencies to damage in different locations depends only on the mode number and the location of damage. The stiffness changes due to damage can be identified by solving a set of underdetermined equations based on the sensitivity matrix. The issues associated with many possible damage locations in large structural systems are addressed, and a means of improving the computational efficiency of damage detection while maintaining the accuracy for large periodic structures with limited available measured natural frequencies, is also introduced in this paper. The incomplete measurements and the effect of random error in terms of measurement noise in the natural frequencies are considered. Numerical results of a periodic spring-mass system of 20 degrees of freedom illustrate that the proposed method is simple and robust in locating single or multiple damages in a large periodic structure with a high computational efficiency.

• 한국의상디자인학회지
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• 제9권2호
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• pp.115-125
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• 2007

A hat is a general term for what human beings wear on their heads in order to protect them from the cold or heat, to be used for ornament, or to symbolize social position. A hat represents the position of a man who wears it, attitude toward the society, and faith for a religion for males. Since men's hats can create their image and uniqueness in casual wear from current fashion items, they are proposed as a fashion accessory item of designers each season. The purpose of this study is to review hats, which are part of costume, in a more analytic method. The research range of this study is hats for men in the upper class in the 17th to 18th centuries from the history of costume when diverse periodic and characteristic costume changes occurred. In the 17th to 18th centuries in the middle of the Chosun Dynasty, changes in costume occurred as the feudal society of the dynasty had been dissolved since the Japanese invasion in 1592. Political power was established in France as the Baroque Age began in the 17th century. Since European costume, especially women's costume led fashion in France, the country represented the age better than any other countries. Aristocratic costume in the Rococo Age of the 18th century was changed to completely different shape of costume after the French Revolution. In this regard, this age was deemed to be the most appropriate for the comparison or costume. Another purpose of this study is to review the common and different features of periodic factors that affect changes in costume by researching the hats of the two countries in the same age in order to understand relation between periodic characteristics and costume throughout history of costume.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.941-949
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• 2006

Nonlinear behavior analysis was used to verify whether a one-way clutch is effective for reducing the torsional vibration of a paired spur gear system under periodic excitation. The dynamic responses were studied over a wide frequency range by speed sweeping to check the nonlinear behavior using numerical integration. The gear system with a one-way clutch showed typical nonlinear behavior. The oscillating component of the dynamic transmission error was reduced over the entire frequency range compared to a system without a one-way clutch. The one-way clutch also eliminated unsteady continuous jump phenomena over multiple solution bands, and prevented double-side contact, even with very small backlash. Installing a one-way clutch on both sides of the gear system was more effective at mitigating the negative effects of external periodic excitation and various parameter changes than a conventional gear system without a one-way clutch.