• 한국산학기술학회논문지
• /
• 제11권2호
• /
• pp.443-448
• /
• 2010

기능이 극대화된 초소형 전자기기를 제조하기 위해 사용되는 적층형 소자들 중, 적층 세라믹 콘덴서(MLCC: Multi Layer Ceramic Capacitor)는 휴대전화, 노트북 등에 전자회로의 평활, 안정화, 노이즈 제거, 커플링 등 다양한 용도로 사용되고 있다. 적층형 세라믹 콘덴서는 생산과정에서 압축소결된 미세 다층구조의 적층형 소자 바(bar)를 하나 하나의 칩으로 절단하여야 한다. 현재 적용되고 있는 cutting, dicing 등의 방법을 대신하여 수율의 향상을 도모하기 위해 진동절삭법을 적용하여 그 특성을 조사하였다. 유연 힌지구조를 이용한 진동 절단 구조를 설계하고 해석하여 적층형 세라믹 콘덴서의 절단에 알맞은 진동절단기구를 제안한다. 또한, 설계결과를 바탕으로 제작된 진동절단 기구의 절단가공 특성을 조사하여 기존 절단법과의 성능비교를 통해 힌지 구조를 이용한 진동 절단의 타당성을 검증하였다.

• 한국추진공학회지
• /
• 제14권6호
• /
• pp.89-102
• /
• 2010

본 논문에서는 항공우주분야의 구동장치와 여러 산업분야에서 응용되고 있는 미래 지향적 구동기의 기술에 대한 사항과 발전방향에 대해 연구하였다. 특히, 항공기 비행조종면 구동장치의 경우 기존에는 기계식 링키지나 무게 대비 출력이 높은 유 공압 구동기가 많이 사용되었으나 최근에는 대부분의 항공기에서 사용 중인 Fly-By-Wire 시스템과 더 나아가 'More Electric', 'All Electric' 시스템으로의 변화가 이루어지고 있다. 전기식 유압구동기와 전기식 구동장치의 경우 효율이나 안전성 그리고 비용적인 측면에서 우수하기 때문에 근래에 지속적인 개발이 진행되고 있다. 또한, 최근에는 구동기의 무게와 정밀도 그리고 응답속도의 향상을 위해 신소재를 이용한 새로운 분야의 구동기들이 개발되고 있다. 따라서 본 연구를 통해서 차세대 항공우주분야 구동장치와 신개념 구동기들의 세부기술 및 발전방향을 제시하고자 한다.

• Smart Structures and Systems
• /
• 제15권4호
• /
• pp.997-1018
• /
• 2015

Structural health monitoring along with damage detection and assessment of its severity level in non-accessible reinforced concrete members using piezoelectric materials becomes essential since engineers often face the problem of detecting hidden damage. In this study, the potential of the detection of flexural damage state in the lower part of the mid-span area of a simply supported reinforced concrete beam using piezoelectric sensors is analytically investigated. Two common severity levels of flexural damage are examined: (i) cracking of concrete that extends from the external lower fiber of concrete up to the steel reinforcement and (ii) yielding of reinforcing bars that occurs for higher levels of bending moment and after the flexural cracking. The purpose of this investigation is to apply finite element modeling using admittance based signature data to analyze its accuracy and to check the potential use of this technique to monitor structural damage in real-time. It has been indicated that damage detection capability greatly depends on the frequency selection rather than on the level of the harmonic excitation loading. This way, the excitation loading sequence can have a level low enough that the technique may be considered as applicable and effective for real structures. Further, it is concluded that the closest applied piezoelectric sensor to the flexural damage demonstrates higher overall sensitivity to structural damage in the entire frequency band for both damage states with respect to the other used sensors. However, the observed sensitivity of the other sensors becomes comparatively high in the peak values of the root mean square deviation index.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
• /
• pp.59-64
• /
• 2002

Effects of the aging treatments on the microstructure and strength of heat affected zone(HAZ) in the welds of a age-hardened Al-Mg-Si alloy, 5N01-T5, were investigated. The base metal aging treatments before MIG welding were conducted at 423K to 473K for 28.8ks Post weld heat treatment(PWHT) to recover the HAZ strength was performed at 448K for 28.8ks. Microstructure observations, hardness measurements and tensile tests were conducted to study properties of the MIG weld joints. The position of the softest region in HAZ where the hardness insufficiently recovered after natural aging and PWHT was at a distance of approximately 15mm from the center of the fusion zone. Hardness of the softest regions after natural aging and PWHT decreased with increase in the base metal aging temperature. TEM observation clarified that strengthening ${\beta}$"(Mg$_2$Si) precipitates and coarse ${\beta}$′ precipitates affected the hardnes of HAZ. Incomplete recover of hardness in HAZ after PWHT was caused by the precipitating of non-hardening ${\beta}$′ phase during the weld thermal cycle. In order to examine the effects of weldheat input and welding speed, the laser weld joints were also investigated and compared with the MIG weld ones. Laser welding had the narrower width of the softened regions in HAZ compared with MIG welding. The hardness of the softest regions of the laser welds after PWHT was higher than that of the MIG welds. Quantitative relations between hardness of the softest region and base metal aging temperature were obtained for both welding processes. Accordingly, the equations to estimate the strength of the weld joints after PWHT with varying base metal temperatures were proposed for MIG welding and laser welding.

• 건축역사연구
• /
• 제7권4호
• /
• pp.61-75
• /
• 1998

The Unite d'Habitation at Marseilles was an experimental project that Le Corbusier had been waiting for since 1920s in order to explore his ideals and visions in mass housing and city planning. As a leader of the first generation members in CIAM, Le Corbusier tried to give a new form and an order to the Unite d'Habitation at Marseilles in both building design and city planning level. The purpose of this research is to investigate the design characteristics of the Unite d'Habitation at Marseilles in three different levels of built environment with a particular emphasis on the process through which an original form is derived from its contextual settings. In the level of city planning, Le Corbusier aimed to reshape traditional low-rise urban housing by deploying several Unites spaciously. Le Corbusier believed that the spacious deployment of Unites would bring us both the functional economy in the city and the natural amenity in the suburbs. As Unite d'Habitation would be called frequently as vertical garden city, the influence of suburban garden city on Unite d'Habitation is apparent. In the building level, the binomial harmony of individual-collectivity was pursued by providing three different public floors and by combining 23 different family unit types in the Unite d'Habitation at Marseilles. In order to visualize the concept of object-type, family units were prefabricated and inserted into the structural frame of the Unite d'Habitation at Marseilles. Two family units are combined to make a three-story section with street corridor in the middle. This three-story section unit is very original as it has access corridor every third floor and each unit could have considerable depth with the help of the living space of two story height. In consideration of formal and plan similarity as well as contextual edivdence, it is concluded that the three-story section of the Unite d'Habitation is derived more from Narkomfin Apartments than from the monastery at Ema or Immuble Villas.

• 대한두개안면성형외과학회지
• /
• 제9권1호
• /
• pp.31-34
• /
• 2008

Introduction: Lymphoepithelioma-like carcinoma of the skin (LELCS) is a rare cutaneous tumor of low grade malignancy and microscopically resembles lymphoepitheliomatous malignancies in the nasopharynx, palatine tonsils, salivary glands and uterine cervix. LELCS presents as scarlet-colored firm nodules or plaques on the face, scalp, or shoulder of middle-aged to elderly individuals. Material and Methods: A 72 year-old female had complained a papule like lesion with intermittent pruritis on the left temple for 2 years. But the lesion was changed to scarlet-colored firm nodule with ulceration. The mass was diagnosed as LELCS on the biopsy. And to confirm that the mass is not metastatic lymphoepithelioma-like carcinoma from other sites or direct tumor extension from the nasopharynx, selective radiographic and laboratory tests were done carefully. Results: Wide excision was performed with general endotracheal anesthesia. The tumor is composed of island of large epithelial cells surrounded by as dense infiltrate of lymphocytes. Immunohistochemical staining with cytokeratin and epithelial membrane antigen(EMA), the tumor cells were positive reaction for stain. And Epstein-Barr virus genome was not detected by in situ hybridization. So, the tumor was confirmed as LELCS. Conclusion: LELCS was described by Swanson at 1988, but has not been reported in the field of plastic surgery of Korea. We report a case of primary LELCS that occurred in the left temple with clinical characteristics, histologic features and references.

• Structural Engineering and Mechanics
• /
• 제44권1호
• /
• pp.51-60
• /
• 2012

Concrete sleepers are essential components of the conventional railway. As support elements, sleepers are always subjective to a variety of time-dependent loads attributable to the train operations, either wheel or rail abnormalities. It has been observed that the sleepers may deteriorate due to these loads, inducing the formation of hairline cracks. There are two areas along the sleepers that are more prone to crack: the central and the rail seat sections. Several non-destructive methods have been developed to identify failures in structures. Health monitoring techniques are based on vibration responses measurements, which help engineers to identify the vibration-based damage or remotely monitor the sleeper health. In the present paper, the dynamic effects of the cracks in the vibration signatures of the railway pre-stressed concrete sleepers are investigated. The experimental modal analysis has been used to evaluate the modal bending changes in the vibration characteristics of the sleepers, differentiating between the central and the rail seat locations of the cracks. Modal parameters changes of the 'healthy' and cracked sleepers have been highlighted in terms of natural frequencies and modal damping. The paper concludes with a discussion of the most suitable failure indicator and it defines the vibration signatures of intact, central cracked and rail seat cracked sleepers.

• Asian Pacific Journal of Cancer Prevention
• /
• 제17권3호
• /
• pp.1357-1362
• /
• 2016

Metastatic gestational trophoblastic neoplasia (GTN) is an uncommon cancer. The principal treatment consists of chemotherapy with or without surgery or radiotherapy. We here retrospectively reviewed the outcomes of metastatic GTN treated at our institute between January, 1999 and December, 2013. Sixty-three patients met the criteria. The median age was 30.0 years and almost 90% were referral cases. Nearly 40% of the studied patients presented with vaginal bleeding while 22.2% were asymptomatic. The most common antecedent pregnancy was hydatidiform mole (57.1%) followed by term pregnancy (20.6%). The median interval time from antecedent pregnancy to the development of GTN was three months and the median pretreatment B-hCG was 58,274 mIU/ml. Stage III (74.6%) was the most common staging followed by stage IV (20.6%) and stage II (4.8%). The most frequent surgery was hysterectomy (31.7%). Thoracotomy and craniotomy were performed in three and two patients, respectively. The most common first line chemotherapy regimen was methotrexate and folinic acid (36.5%) followed by EMA (etoposide, methotrexate, actinomycin D) (34.9%), EMACO (etoposide, methotrexate, actinomycin D, cyclophosphamide, vincristine) (17.5%) with the remission rate of 66.7%. Nearly one-third of the patients were given a subsequent chemotherapy regimen after failure with the first line therapy and showed a final response rate of 73.0%. However, in stage IV, the response to first line treatment was only 38.5%. In conclusion, the outcomes of metastatic GTN were poor especially with the higher stages.

• 말소리와 음성과학
• /
• 제6권4호
• /
• pp.3-15
• /
• 2014

An articulatory study (using an Electromagnetic Articulography, EMA) was conducted to explore effects of prosodic boundary strength (Intonational Phrase/IP versus Word/Wd), and focus (Focused/accented, Neutral, Unfocused/unaccented) on the kinematic realization of /m/ in the coda (${\ldots}$am#i${\ldots}$) and the onset (${\ldots}$a#mi${\ldots}$) conditions in Korean. (Here # refers to a prosodic boundary such as an IP or a Wd boundary). Several important points have emerged. First, the boundary effect on /m/s was most robustly observed in the temporal dimension in both the coda (IP-final) and the onset (IP-initial) conditions, generally in line with cross-linguistically observable boundary-related lengthening patterns. Crucially, however, in contrast with boundary-related slowing-down effects that have been observed in English, both the IP-final and IP-initial temporal expansions of Korean /m/s were not accompanied by an articulatory slowing down. They were, if anything, associated with a faster movement in the lip opening (release) phase (into the vowel). This suggests that the mechanisms underlying boundary-related temporal expansions may differ between languages. Second, observed boundary-induced strengthening effects (both spatial and temporal expansions, especially on the IP-initial /m/s) were remarkably similar to prominence (focus)-induced strengthening effects, which is again counter to phrase-initial strengthening patterns observed in English in which boundary effects are dissociated from prominent effects. This suggests that initial syllables in Korean may be a common focus for both boundary and prominence marking. These results, taken together, imply that the boundary-induced strengthening in Korean is different in nature from that in English, each being modulated by the individual language's prosodic system. Third, the coda and the onset /m/s were found to be produced in a subtly but significantly different way even in a Wd boundary condition, a potentially neutralizing (resyllabification) context. This suggests that although the coda may be phonologically 'resyllabified' into the following syllable in a phrase-medial position, its underlying syllable affiliation is kinematically distinguished from the onset.

• 한국주거학회논문집
• /
• 제26권5호
• /
• pp.153-161
• /
• 2015

The purpose of this study is to understand Le Corbusier's idea of public and private spaces, and the hierarchical spatial structure in his multi-family housings. It investigates the origin of Le Corbusier's ideology about the public and private spaces in his multi-family housing projects. Precedents those influenced his ideas are two: first, Fourier's ideal community model $Phalanst\grave{e}re$; second, Monastery of Ema near Florence. In both cases, private and public spaces and intermediate spaces were in clear hierarchy and also in harmony. Le Corbusier focused on the interplay of individual and collective life. This study analyzed the spatial composition of Le Corbusier's three multi-family housing models. They are Immeubles-Villas of Ville contemporaine pour 3 millions d'habitants (1922), Immeubles-Villas at Pavillion of l'Esprit Nouveau (1925), Unite d'habitation at Marseille (1945). The three projects are different according to size and periodical characteristics. However, they followed his basic principle for spatial composition about multy-family housing. His 'method of harmony for public and private space' is as follows: first, the securing of clear personal space; second, the importance of the intermediate space; Third, the essential understanding of communal space. Through this study, it was reaffirmed that the 'multi-family housing is a space where individuals and the whole co-exist'.