In this paper, we have studied Sogyupyo (小圭表, small noon gnomon) of the Joseon dynasty. According to the Veritable Records of King Sejong (世宗, 1418 - 1450), Daegyupyo (大圭表, large noon gnomon) with a height of 40-feet [尺] was constructed by Jeong, Cho (鄭招) and his colleagues in 1435, and installed around Ganuidae (簡儀臺, platform of Ganui). On the contrary, the details of Sogyupyo are unknown although the shadow length measurements by Daegyupyo and Sogyupyo are found on the Veritable Records of King Myeongjong (明宗, 1545 - 1567). By analysing historical documents and performing experiments, we have investigated the construction details of Sogyupyo including its development year, manufacturer, and installation spot. We have found that Sogyupyo would be manufactured by King Sejong in 1440 and placed around Ganuidae. And Sogyupyo would be five times smaller than Daegyupyo, i.e., 8-feet. On the basis of experiments, we suggest that although it is smaller, Sogyupyo was equipped with a bar [橫梁] and a pin-hole projector [影符] like Daegyupyo in order to produce the observation precision presented in the Veritable Record of King Myeongjong.

Since the thirteenth century, large scale facilities and various instruments for astronomical observation were built and installed in East Asia. During the Yuan Dynasty, S. ti.ntai (Beijing astronomical observatory in the Yuan Dynasty, 司天臺) was built in Beijing in 1279. Various astronomical instruments, including Ganui (Jianyi, simplified armillary sphere, 簡儀), Yang-yi (upward hemisphere, 仰儀) and Gyupyo (gnomon, 圭表) were installed in this observatory. These astronomical instruments were modified and improved by researchers of the Joseon Dynasty. Ganuidae (Joseon astronomical observatory, 簡儀臺) was built in Gyeongbokgung (or Gyeongbok palace, 景福宮), Seoul. Its scale was 31 Cheok (Korean feet in the Joseon Dynasty, 尺) in height, 47 Cheok in length and 32 Cheok in width. Lee, Cheon (李蕆, 1376~1451), a responsible leader of Ganuidae project, set up various astronomical instruments with his colleagues. Ganui and Jeongbangan (direction-determining board, 正方案) were installed at the top of this observatory. Gyupyo was installed at the west side of this observatory and Honui (armillary sphere, 渾儀) and Honsang (celestial globe, 渾象) were installed in a small pavilion which was located next to Gyupyo. A decade after installation, this observatory was moved to the north-west side of the palace but almost destroyed during Japanese invasion of Korea in 1592 except Ganuidae. We have analyzed documents about Ganuidae and investigated Chinese remains of astronomical observatories and artifacts of astronomical instruments. In this paper, we suggest the appearance, structure, arrangement and scale of Ganuidae, which are expected to be used for the restoration of Ganuidae at some day in the near future.

Ti-6Al-4V ELI (Extra Low Interstitial) alloy has been widely used as an alternative to bone due to its excellent biocompatibility. However, it still has many problems, including a high elastic modulus and toxicity. Therefore, nontoxic biomaterials with a low elastic modulus should be developed. However, the fabrication of a uniform coating is challenging. Moreover, the coating layer on Ti and Ti alloy substrates can be peeled off after implantation. To overcome these problems, it is necessary to produce bulk Ti and Ti alloy with hydroxyapatite (HA) composites. In this study, Ti, Nb, and Zr powders, which are biocompatible elements, were milled in a mixing machine (24h) and by planetary mechanical ball milling (1h, 4h, and 6h), respectively. Ti-35%Nb-7%Zr and Ti-35%Nb-7%Zr-10%HA composites were fabricated by spark plasma sintering (SPS) at 1000˚C under 70MPa using mixed and milled powders. The effects of HA addition and milling time on the biocompatibility and physical and mechanical properties of the Ti-35%Nb-7%Zr-(10%HA) alloys have been investigated. Ti2O, CaO, CaTiO3, and TixPy phases were formed by chemical reaction during sintering. Vickers hardness of the sintered composites increases with increased milling time and by the addition of HA. The biocompatibilty of the HA added Ti-Nb-Zr alloys was improved, but the sintering ability was decreased.

The aim of this study was to investigate microstructures and mechanical properties of nano-sized Ti-35 wt.%Nb-7 wt.%Zr-10 wt.%CPP composite fabricated by high energy mechanical milling (HEMM) and pulse current activated sintering (PCAS). Grain growth of the mechanically milled powder was prevented by performing PCAS. The principal advantages of calcium phosphate materials include: similarity in composition to the bone mineral, bioactivity, osteoconductivity and ability to form a uniquely strong interface with bone. The hardness and wear resistance property of nano-sized Ti-35 wt.%Nb-7 wt.%Zr-10 wt.%CPP composites increased with increasing milling time because of decreased grain-size of sintered composites.

In this paper we have reconstructed an armillary sphere based on the Method of an Armillary Sphere Making described in the Volume 1 of The Collection of Writings on the Scientific Instruments-Uigijipsol (儀器輯說, two volumes) edited in the 1850's by Nam Byong-Chul (南秉哲, 1817-1863) who was a famous Korean states-man-scientist. Nam achieved convenience and accuracy in the measurements of stellar positions in the manner of selective setting the equatorial, ecliptic and horizontal poles by adding a pole axis exchange ring called Jaigeukkwon (載極圈) between the Three Arrangers of Time and Four Displacements. We made use of 3-dimensional graphic software for modelling Nam's armillary sphere which consisted of five layers-eight rings. Results of simulation showed that the pole axis exchange ring functioned properly in setting the equatorial, ecliptic and horizontal coordinates simply by exchange of positions of specified holes on the ring. We ascertained that the invention of Jaigeukkwon solved inherent problems in the conventional Chinese armillary sphere in computation of real ecliptic coordinates. It was revealed that Nam Byong-Chul made great contributions in the East Asian history of armillary sphere making.

본 논문에서는 Telos Device를 이용한 검사 시 인가한 daN 힘의 차이와 무릎의 안정성에 관여하는 근육들의 개인차에 따른 전방십자인대의 동요 정도에 대해 연구하고자 한다. Telos Device를 이용한 Lachman Test로 검사하였으며, 오른쪽과 왼쪽을 각각 0, 15, 30 daN, 운동부하 후 30 daN의 힘으로 변화하며 검사하여 전방십자인대의 변화를 측정하였다. 근육량 측정은 CT(Computed Tom ography)를 이용하였으며, 힘줄(tendon)을 피해 근육을 측정하기 위해 무릎뼈(patella) 상방 8 cm의 위치를 검사하였다. 전방십자인대(Anterior Cruciate Ligament)의 변화 정도는 Piview의 Caliper 기능을 이용하여 측정 하였으며, 근육량은 CT 단면 영상을 Image J 프로그램을 이용하여 지방을 제외한 뼈와 근육의 면적을 측정 하였다. 측정값들은 SPSS Ver. 18을 이용하여 결과 값을 얻었다. Telos Device 로 인가하는 힘의 변화에 따라 전방십자인대의 동요 정도를 측정한 결과 오른쪽과 왼쪽 모두 15 daN 과 30 daN의 힘을 인가하였을 때 통계적으로 유의한 무릎 동요의 차가 발생하였으며(p<0.05), 30 daN 과 운동부하 후 30 daN 에서의 동요 정도는 유의한 차이를 보이지 않았다(p>0.05). 근육면적의 차이와 전방십자인대의 동요 정도와의 상관관계에서 15 daN의 압력에서 오른쪽 r=-0.45, 왼쪽 r=0.44로 음의 상관관계를 보였다(p<0.05). Telos Device에 인가 하는 힘의 정도에 따라 전방십자인대의 동요는 커지는 것으로 분석되며, 또한 개인의 근육량의 차이에 따라 전방십자인대의 동요 정도에도 차이를 보이는 것으로 분석된다. 따라서 개인의 근육량의 차이에 따라 Telos Device에 인가되는 힘도 변화되어야 하는 것으로 사료된다.