PSC거더 합성교량에 있어 노후(손상)된 바닥판을 교체할 경우에는 기존에 설치된 철근 전단연결재의 손상과 함께 파 쇄에 따른 소음 및 비산먼지 등이 많이 발생한다. 이러한 환경적 문제와 함께 교체공사 기간이 길어져 경제적 비용 또한 크게 증가한다. 본 연구에서는 이러한 문제를 해결하기 위해 PSC거더에 매립되지만 쉽게 분리할 수 있는 분리식 전단연결재를 제안 하였다. 제안한 분리식 전단연결재의 전단강도성능과 파괴거동을 확인하기 위해 유한요소해석을 통한 변수연구와 함께 수평전 단실험을 수행하였다. 해석연구를 통해 T-sleeve 하부에 Y형상의 테이퍼진 면을 갖는 경우에 볼트체결력에 따른 쐐기효과로 인 해 T-sleeve와 볼트 사이의 제작 공차가 있더라도 초기 슬립이 발생하지 않고 충분한 초기강성을 확보하는 것을 확인하였다. 또 한, 전단연결재의 배치 방향에 따른 영향은 전단성능에 영향을 주지 않는 것을 확인하였다. DY전단연결재는 기존 방식인 철근 전단연결재 모델과 비교실험을 통해 전단강도성능은 동등 이상을 확보하고 있으며, 슬립변위량 또한 연성설계기준인 6mm 이상 을 만족하는 것을 확인하였다. 본 연구를 통해 제안된 분리식 전단연결재는 추가적으로 합성거더 실험 등의 검증을 거친다면 노후 바닥판의 철거 및 교체에 유용한 대안이 될 수 있을 것으로 판단된다.

Osteoblastoma(OB) is a rare tumor of bone representing less than 1 % of all tumors of the maxillofacial region. The lesion usually appears in vertebral column, sacrum, long bones but rare in mandible or maxilla. The lesion occurs most commonly at age from 3 to 78 years with the mean age of 22-23 years. In this article, we report one case of OB occurred in mandible. With clinical examination and radiological diagnosis, preliminary diagnosis was made as Fibro-osseous lesion, osteomyelitis or cementoblastoma. Under general anesthesia, associated tooth was extracted and excisional biopsy was done. After microscopic examination, it was diagnosed as OB. The patients which we presented did not complain any specific complications, and showed good prognosis.

Central odontogenic fibroma(COF) is an extremely rare benign tumor that accounts for 0.1% of all odontogenic tumor. COF is regarded by the World Health Organization(WHO) as a benign odontogenic neoplasm derived from mesenchymal odontogenic tissue. The lesion occurs most commonly in the mandible and patients ranging in age from11 to 80years with mean age of 34years. In this article, we report two case of COF. Case I was associated odontoma and impacted tooth. Odontoma and impacted tooth was removal under general anesthesia. After microscopic examination, finally we diagnosis this lesion as COF. Patients of case II showed radiolucent lesion at the mandible. Lesion was enucleated under general anesthesia. After microscopic examination, finally we diagnosis this lesion as COF. The patients which we presented did not complain any specific complications, showed good prognosis.

We study the operation of a lunisolar calendar in Korea and its time data calculation method. The dates based on the lunisolar calendar have been conventionally used in Korea after the Gregorian calendar was introduced in 1896. With the Astronomy Act enacted in 2010, the lunisolar calendar is presently being used as an official calendar along with the Gregorian calendar. However, no institutionalized regulations have been provided on the time data calculation method by the lunisolar calendar. The Korea Astronomy and Space Science Institute very recently established the regulations on the lunisolar calendar operation in Korea. We introduce the regulations together with historical substances and analyze the time data calculated according to the regulations for 600 years from 1901 to 2500. From our study, we find that the value of ΔT (i.e., the difference between the terrestrial time and the universal time) is the most critical parameter causing uncertainty on the data. We also find that all new Moon days in the almanacs agree with our calculations since 1912. Meanwhile, we find that new Moon and winter solstice times are found to be very close to midnight in 38 and five cases, respectively. For instance, the new Moon time on January 14, 2097 is 0 h 0 min 8 s. In this case, deciding the first day (i.e., new moon day) in a lunar month is difficult because of the large uncertainty in the value of ΔT. Regarding with a lunar leap month, we find that the rules of inserting the leap month do not apply for 17 years. In conclusion, we believe that our findings are helpful in determining calendar days by using the lunisolar calendar.

The effects of the heat treatment temperature and of the atmosphere on the dehydrogenation and hydrogen reduction of ball-milled TiH2-WO3 powder mixtures are investigated for the synthesis of Ti-W powders with controlled microstructure. Homogeneously mixed powders with refined TiH2 particles are successfully prepared by ball milling for 24 h. X-ray diffraction (XRD) analyses show that the powder mixture heat-treated in Ar atmosphere is composed of Ti, Ti2O, and W phases, regardless of the heat treatment temperature. However, XRD results for the powder mixture, heat-treated at 600oC in a hydrogen atmosphere, show TiH2 and TiH peaks as well as reaction phase peaks of Ti oxides and W, while the powder mixture heat-treated at 900oC exhibits only XRD peaks attributed to Ti oxides and W. The formation behavior of the reaction phases that are dependent on the heat treatment temperature and on the atmosphere is explained by thermodynamic considerations for the dehydrogenation reaction of TiH2, the hydrogen reduction of WO3 and the partial oxidation of dehydrogenated Ti.

Porous W with spherical and directionally aligned pores was fabricated by the combination of sacrificial fugitives and a freeze-drying process. Camphene slurries with powder mixtures of WO3 and spherical PMMA of 20 vol% were frozen at −25 oC and dried for the sublimation of the camphene. The green bodies were heat-treated at 400 oC for 2 h to decompose the PMMA; then, sintering was carried out at 1200 oC in a hydrogen atmosphere for 2 h. TGA and XRD analysis showed that the PMMA decomposed at about 400 oC, and WO3 was reduced to metallic W at 800 oC without any reaction phases. The sintered bodies with WO3-PMMA contents of 15 and 20 vol% showed large pores with aligned direction and small pores in the internal walls of the large pores. The pore formation was discussed in terms of the solidication behavior of liquid camphene with solid particles. Spherical pores, formed by decomposition of PMMA, were observed in the sintered specimens. Also, microstructural observation revealed that struts between the small pores consisted of very fine particles with size of about 300 nm.

현재까지 발표된 연구에 따르면 순환골재에는 약 20~40 중량%의 잔류 모르타르가 존재하는 것으로 알 려져 있으며, 순환골재에 포함된 잔류 모르타르의 함량에 따라 콘크리트의 강도 및 탄성계수 등의 물리적 거동에도 영향을 미치게 된다. 이러한 잔류 모르타르가 포함된 순환골재를 사용하여 ASTM C-1260의 규 정에 따라 알칼리 실리카 반응성 평가를 진행하게 될 경우, 포함되어 있는 잔류 모르타르 함량이 많아짐 에 따라 원골재의 비율이 줄어들게 되어 올바른 실험 결과값을 얻을 수 없는 경우가 발생하게 된다. 이러 한 문제점으로 인하여 순환골재를 재활용하기에 앞서 원골재의 내구적 특성을 파악하는 것이 매우 중요할 것으로 판단된다. 따라서 본 연구에서는 순환골재에 포함된 잔류 모르타르가 골재의 알칼리 실리카 팽창에 미치는 영향 을 평가하기 위해 동일한 모암을 가지며 잔류 모르타르 함량이 다른 순환골재 2종을 1M 농도의 염산 용 액으로 잔류 모르타르를 제거하여 염산처리 전 ․ 후 골재의 화학적 구성성분을 분석하고(그림 1), ASTM C-1260 규정에 따라 알칼리 실리카 반응성을 평가 및 분석하였다. 실험결과 흡수율이 6%를 초과하는 재 생골재 RA1의 경우 ASR 팽창거동은 원골재 대비 44%까지 감소하였으며, 흡수율 3% 미만인 순환골재 RA2의 경우 78%까지 감소하였다(그림 2). 따라서 본 연구에 사용된 골재의 경우, 원골재에 부착된 잔류 모르타르 함량의 대소에 따라 ASR시편의 팽창성은 실제 골재의 팽창성에 비해 50%이하로 감소되어 거동 할 수 있는 것으로 조사되었다.

The synthesis of NiTi alloy powders by hydrogen reduction and dehydrogenation process of NiO and TiH2 powder mixtures is investigated. Mixtures of NiO and TiH2 powders are prepared by simple mixing for 1 h or ball milling for 24 h. Simple-mixed mixture shows that fine NiO particles are homogeneously coated on the surface of TiH2 powders, whereas ball milled one exhibits the morphology with mixing of fine NiO and TiH2 particles. Thermogravimetric analysis in hydrogen atmosphere reveals that the NiO and TiH2 phase are changed to metallic Ni and Ti in the temperature range of 260 to 290oC and 553 to 639oC, respectively. In the simple-mixed powders by heat-up to 700oC, agglomerates with solid particles and solidified liquid phase are observed, and the size of agglomerates is increased at 1000oC. From the XRD analysis, the presence of liquid phase is explained by the formation and melting of NiTi2 intermetallic compound due to an exothermic reaction between Ni and Ti. The simple-mixed powders, heated to 1000oC, lead to the formation of NiTi phase but additional Ni-, Ti-rich and Ti-oxide phases. In contrast, the microstructure of ball-milled powders is characterized by the neck-grown particles, forming Ni3Ti, Ti-oxide and unreacted Ni phase.

현재 국내에서는 천연골재 수급의 어려움과 건설폐기물 재사용의 일환으로 기존의 천연골재를 순환골 재로 대체하기 위한 많은 연구가 진행되고 있으며 국가적 차원으로도 순환골재의 사용을 의무화 하였다. 향후 순환골재의 사용량이 늘어날 것으로 예상됨에 따라 순환골재에 대한 전반적인 기초연구가 필요한 실 정이다. 순환골재는 천연골재에 비해 낮은 비중, 높은 흡수율, 각종 이물질 함유 등의 특징을 가지며, 이러한 순환골재를 사용하여 만든 콘크리트는 압축강도와 탄성계수 등의 물성에 있어서 낮은 경향을 나타낼 뿐만 아니라, 커다란 품질편차를 보인다. 따라서 배합 설계시 이론값을 통한 현장강도 계산을 적절히 적용할 수 없을 뿐만 아니라 실내시험과 현장시험간의 결과치가 유사하지 않은 경향을 보일 수 있다. 따라서 순 환골재의 적절한 사용을 위해서는 지속적인 연구를 통한 데이터의 축적이 필요하다. 따라서 본 연구에서는 천연골재 3종, 순환골재 4종을 대상으로 골재 기초 물성 분석 및 XRF 분석을 하 였으며, 또한 보통 포틀랜드 시멘트 외에 고로 슬래그 미분말, 저알칼리 시멘트를 사용하여 알칼리 실리 카 반응성을 촉진 모르타르 봉 시험법(ASTM C-1260)으로 평가 하였다.

The article examines the attempts made at economic revitalisation of Ljubljana’s inner city and the consequences or “collateral damage” of this process. A lot of attention is given to the wider socio-cultural context, in which art istic practices are embedded in the city, and to the Slovenian population’s perception of such practices. Artistic groups and their practices are in this sense used as part of an ‘interim development’ strategy, i.e. temporary guests(non-statutory tenants) are warmly welcomed because their (sub)cultural capital happens to cultivate the area, making it "cool" and attractive, but when the value of the area’s real estate begins to rise their low-income status does not grant them any tenant protection. Regardless of the social role they played in revitalising the city, these groups are therefore gradually ousted from neighbourhoods, which quite ironically are often advertised in the real estate market as the city’s "Bohemian" or "cultural" quarters. This makes us aware of the lack of unique alternative or informal spaces, venues for alternative art movements and practices in the cities. These issues are presented on the cases of the alternative spaces of Metelkova and the Rog Factory, both located in Ljubljana’sinnercity.

몽골에서 본격적으로 한국어교육이 시작된 지 이제 20여년의 기간이 지나고 있다. 그동안 몽골에서의 한국어교육은 주로 한국어 교수법 및 교재제작을 위주로 하여 몽골인들에게 제 2외국어로써의 한국어 교과목의 확충과 교재개발에 있어서 적지 않은 성과를 거두고 있는 것으로 사료된다. 한편 이러한 학습교재와는 별도로 특히 주목할 만한 현상으로는 몽골인을 위한 한국어사전 편찬사업을 들 수 있다. 또한 그 중요성에도 불구하고 몽골에서의 한국어 사전편찬 과정에는 상당한 문제점들이 노정되고 있다. 따라서 본고에서는 몽골에서의 한국어 사전편찬 현황 및 문제점에 대하여 논의하여 차후 사전편찬의 개선점과 미비점을 보완하는 계기를 마련하고자 한다.

As technology develops, more advanced technologies involving GPS, GIS, RFID and sensor networks have been adopted in agriculture sector for u-Farm. However, technology adoptions have been evaluated as ineffective. Farmers and agri-business have low level of understanding on technology so it is not efficiently utilized. This study introduces a case of RFID/sensor networks of mushroom farm as a u-Farm case study, focusing on developing a framework for analysis of u-Farm investment returns. RFID and sensor networks improve real-time production control, processing management, and traceability. Integration of RFID and sensor networks leads to innovation into the mushroom farm, reducing labor cost, increasing productivity, and improving quality of the mushroom. The ROI which is used as an indicator of performance indicator is 413%.

In this paper, a soft robotic arm which can prevent impact injury during human-robot interaction is introduced. Two degrees of freedom joint are required to realize free movement of the robotic arm. A robotic joint concept with a single degree of freedom is presented using simple inflatable elements, and then extended to form a robotic joint with two degrees of freedom joint using similar manufacturing methods. The robotic joint with a single degree of freedom has a joint angle of 0° bending angle when both chamber are inflated at equal pressures and maximum bending angles of 28.4° and 27.1° when a single chamber if inflated. The robotic joint with two degrees of freedom also has a bending angle of 0° in both direction when all three chambers are inflated at equal pressures. When either one or two chambers were pressurized, the robotic joint performed bending towards the uninflated chambers.

Entropy is a measure of disorder or uncertainty. This terminology is qualitatively used in the understanding of its correlation to pollution in the environmental area. In this research, three different entropies were defined and characterized in order to quantify the qualitative entropy previously used in the environmental science. We are dealing with newly defined distinct entropies E1, E2, and E3 originated from Shannon entropy in the information theory, reflecting concentration of three major green house gases CO2, N2O and CH4 represented as the probability variables. First, E1 is to evaluate the total amount of entropy from concentration difference of each green house gas with respect to three periods, due to industrial revolution, post-industrial revolution, and information revolution, respectively. Next, E2 is to evaluate the entropy reflecting the increasing of the logarithm base along with the accumulated time unit. Lastly, E3 is to evaluate the entropy with a fixed logarithm base by 2 depending on the time. Analytical results are as follows. E1 shows the degree of prediction reliability with respect to variation of green house gases. As E1 increased, the concentration variation becomes stabilized, so that it follows from linear correlation. E2 is a valid indicator for the mutual comparison of those green house gases. Although E3 locally varies within specific periods, it eventually follows a logarithmic curve like a similar pattern observed in thermodynamic entropy.