리황의 철학사상에 대하여

변정암 慶北大學校 退溪硏究所 2004 退溪學과 韓國文化 Vol.- No.35-2

퇴계 이황은 16세기의 대표적인 관념론철학자이다. 이황의 철학사상은 총체적으로 존재론과 의식론, 윤리설로 이루어져 있다. 우선 그의 존재론에서는 이를 운동능력을 가지고 스스로 운동하며 우주만물을 낳는 '능발능생'의 존재로 규정하면서, 그 위치를 상제의 높이에까지 끌어올려 '극존무대'의 절대적 존재로 정립하였다. 또한 이것에 기초하여 이일원론적 경향을 뚜렷이 하였는데, 이것은 그의 인식론에서도 명백히 나타나고 있다. 그는 인식주체와 인식대상의 원칙적이며 본질적인 구분을 부정하였는데, 이것은 인간의 인식과정은 본질에 있어서 자기의 본성 속에 이미 선천적으로 갖추어져 있는 이를 사물현상을 통하여 확인해보는 과정에 불과하다는 것이다. 더 나아가 사물현상에 대한 인식과정이 이 스스로의 자기 발현에 의한 자기 인식과정임을 명시하는 '이자도'설을 주장하였다. 이황은 윤리설 또한 이일원론에 기초하여 전개하였는데, 대표적인 것은 '주경(主敬)'론이다. '경'에는 두 개의 단계가 있는데, 첫 단계는 개개의 사물을 각각 전일하는 단계이고, 두 번째 단계는 하나에서 완전한 조화를 이루는 단계 즉. '물아통일'의 경지이다. 이처럼 '물아통일'을 '경'의 최고 이상경계로 세운 것은 '천리'에 부합되는 인간의 도덕적 완성의 필연성을 확증하자는데 있었다. Yi Hwang in the pen name Toe'gye, is the representative philosopher of idealism in the 16th century. His philosophy mainly consists of ontology, study of consciousness, and ethics. Considering reason (li) and energy (ki) as a unified unit, Yi Hwang denies the distinction between the subject of thinking and the object. According to his theory, a man cognizes phenomenon, availing his inborn ability to reason, which is called as the theory of Lijado.

Altitude Integration of Radar Altimeter and GPS/INS for Automatic Takeoff and Landing of a UAV

Am Cho,Young-shin Kang,Bum-jin Park,Chang-sun Yoo,Sam-Ok Koo 제어로봇시스템학회 2011 제어로봇시스템학회 국제학술대회 논문집 Vol.2011 No.10

An intelligent tilt-rotor UAV is being developed by the Smart UAV Development Center of Korea Aerospace Research Institute. It is equipped with integrated GPS/INS system and RALT(radar altimeter) for automatic takeoff and landing. GPS/INS integration system gives the altitude referenced to WGS-84 ellipsoid which can be vulnerable to external multipath environment. RALT provides the aircraft AGL(above ground level) height with the centimeter level accuracy which is dependent on ground surface characteristics. This paper describes the simple KF(Kalman Filter) setup to integrate altitude information from GPS/INS integration system and RALT with its operational logic. It is evaluated using the data obtained from real flight tests. The result shows proposed method provides highly reliable AGL height for automatic takeoff and landing and compensates GPS/INS derived altitude drift efficiently. The proposed method can be easily applied to the existing system without modifying off-the-shelf GPS/INS integration system. It also has a small computational burden due to its simple model.

Comparison of Geostrophic Current Estimation around the Korean Peninsula from Remote Sensing-based MSS Models

Cho, Jaemyoung,Lee, Dongha,Lee, Miran,Cho, Jungho,Yun, Hongsik,Jeong, Taejun,Jang, Am,Kim, Taeyun BioOne (Coastal Education and Research Foundation) 2013 JOURNAL OF COASTAL RESEARCH Vol.65 No.-

<P>Altimetry satellites like Geosat, ERS-1/2, Envisat and Topex-Poseidon, which have been developed and deployed since the 1970s, have collected immense arrays of data on the sea, and the data thus gathered have been used in oceanography as well as in a variety of scientific disciplines, such as geophysics and geodesy. The mean dynamic ocean topography or Sea Surface Topography (SST), obtained by calculating the difference between the Mean Sea Surface (MSS) and the geoid surface, plays a critical role in determining the earth's shape and geoid as well as in the precision modeling of the earth's gravity field, ocean currents, and tidal waves. In the study, the MSS_CNES_CLS10 (Centre National d'Etudes Spatiales Collectre Localisation Satellites 2010) and DTU10MSS (Danmarks Tekniske Universitet 2010) MSS models calculated with the data obtained by a number of altimetry and gravity observation satellites, such as Topex/Poseidon, CHAMP, and GRACE, as well as a geoid model calculated from the EGM2008 gravity field model, were employed to determine the SST around the Korean Peninsula and to calculate its geostrophic current, the key source of the sea surface current. The SST and geostrophic current were also calculated using the MSS_CNES_CLS10 and DTU10MSS MSS model calculated from the satellite data, as well as a geoid model calculated from the EGM2008 earth's gravity field model, with a maximum degree and order 20 In the study, comparing calculated velocity with measured data and previous researches, calculated velocity of current is as 2 to 4 times faster than measured velocity at the East Sea which changes depth rapidly. However, it is similar to velocity and direction at over 40km far from the coastal area and the Yellow Sea which changes depth gradually. Also, as a result of comparison with two MSS models, MSS_CNES _CLS10 model is more accurate than DTU10MSS model, but the difference was trivial. If it is possible to estimate the movement of oceanic current which are affected by wind, pressure, density, tides and temperature of ocean, and add onto method of estimating geostrophic current used in this research, we will be able to estimate in more detail at the oceanic current This study would provide some useful data for maritime voyage and fishery.</P>

Air data System Calibration Using GPS Velocity information

Am Cho,Young-shin Kang,Bum-jin Park,Chang-sun Yoo,Sam-Ok Koo 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Most aircrafts are equipped with an air data system to measure airspeed, angle-of-sideslip(AOS) and so on. An air data system consists of Pitot-static tube and gimbal-mounted weathervane. The static pressure obtained by Pitot-static tube is affected by fuselage nose and angle-of-attack(AOA). To measure AOA and AOS accurately, weathervane should be placed out of boundary layer around fuselage nose. But due to structural problems, it is not easy to keep sufficient distance between static-hole of Pitot-static tube and fuselage nose. This gives rise to the error of measured air data and it is difficult to correct this error by wind-tunnel test or computational method. Thus, air data system must be calibrated through flight test after installation. This paper proposes the Kalman filter setup to calibrate static pressure, or airspeed and barometric altitude using GPS ground velocity. And also Kalman filter based AOS calibration method is proposed using flight data. Proposed methods are verified by simulation and real flight data of Smart UAV.

Airflow Angle and Wind Estimation Using GPS/INS Navigation Data and Airspeed

Am Cho,Young-shin Kang,Bum-jin Park,Chang-sun Yoo 제어로봇시스템학회 2013 제어로봇시스템학회 국제학술대회 논문집 Vol.2013 No.10

The aircraft autopilot needs the feedback of airflow angles, that is, angle-of attack and sideslip angle to control the aircraft. The airflow angles measured by a mechanical vane are not accurate and very noisy for low airspeed. Moreover, the vane has a mechanical failure risk. This paper describes the extended Kalman filter based method to estimate the airflow angles and three-dimensional wind speed under constant wind condition. In addition, it can correct the scaling error of the airspeed of an aircraft. It uses the airspeed measurements, constant wind condition and the sideslip angle computed from GPS/INS navigation data and stability and control derivatives estimated from flight data. Simulation results show that the proposed method works well in various conditions. It is expected that estimated airflow angles will be able to replace the airflow angles measured by a primary system. Estimated wind speed can also be used to reconstruct the GPS/INS navigation system by correcting the airspeed in the case of GPS failure.

On the effects of the characteristics of the titanium oxide to the osteoblast cell culture

Cho, Sung-Am The Korean Academy of Prosthodonitics 2000 대한치과보철학회지 Vol.38 No.3

Statement of problem. Confusion about the relationship of surface characteristics of implant to osteoblast cell attachment. Purpose. This study attempted to bone cell attachment to the implant surface which was modified by heat. Material and methods. Commercially pure titanium grade 2, $4{\times}4mm$ sheet 40 pieces were treated for 10 minutes with ultrasonic cleaner with methylethyl ketone, ethanol, deionized distilled water, and half of the specimen 20 pieces were heat treated in $980^{\circ}C$ for 15 minutes. All 40 specimens were autoclaves. Total 6 dishes were prepared, 3 dishes were for control group, and the other 3 dishes were for heat treatment. In fourth day, cell account was done. Conculsion. The change of surface characterization by heat treatment could affect the cell attachment in the early stage however, the change of surface characterization would not be prolonged.

On the effect of the characteristics of the titanium oxide to the osteoblast cell culture.

Cho, Sung-Am 경북대학교 병원 2003 경북대학교병원의학연구소논문집 Vol.7 No.1

Statement of problem. Confusion about the relationship of surface characteristics of implant to osteoblast cell attachment. Purpose. This study attempted to bone cell attachment to the implant surface which was modified by heat. Material and methods. Commercially pure titanium grade 2,4×4㎜ sheet 40 pieces were treated for 10 minutes with ultrasonic cleaner with methylethyl ketone, ethanol, deionized distilled water, and half of the specimen 20 pieces were heat treated in 980℃ for 15 minutes. All 40 specimens were autoclaves. Total 6 dishes were prepared, 3 dishes were for control group, and the other 3 dishes were for heat treatment. In fourth day, cell account was done. Conculsion. The change of surface characterization by heat treatment could affect the cell attachment in the early stage however, the change of surface characterization would not be prolonged.

The bone integration effects of platelet-rich fibrin by removal torque of titanium screw in rabbit tibia

Cho, Sung-Am,Lee, Byung-Kil,Park, Sang-Hun,Ahn, Jae-Jin Informa UK Ltd. 2014 Platelets Vol.25 No.8

<P>Platelet-rich fibrin (PRF) is nowadays often used in various fields, but no removal torque studies have yet been done to evaluate the effects of the platelet-rich fibrin on the bone integration at the initial healing period. An experimental study have been performed in rabbits to evaluate whether the complete PRF clots can accelerate the bone integration of implants at the initial healing period after creating bone defects in tibias. The effec t of the complete PRF clots on bone integration was studied in two rabbit groups, 4-week group (group A) and 6-week group (group B) after preparing bony defects. Artificial bony defects were prepared in the tibias of rabbits. The complete PRF clots was applied to the defects in the experimental group, whereas the defects were unfilled in the control group. Four weeks later, machined implants were installed into the rabbit tibias (group A). Six weeks after installation, the removal torque from nine rabbits was measured to examine the bone healing effect of PRF. In another rabbits (group B), 6 weeks after preparing bony defects, installation was performed, and another 6 weeks after installation, the removal torque from nine rabbits was measured. The authors found a positive significant effect of the complete PRF clots on bone integration (higher bone density) in group A installed at 4 weeks after preparing bony defects (<I>p</I> = 0.008; <I>t</I>-test), but not in group B installed at 6 weeks after preparing bony defects (<I>p</I> = 0.677).</P>

The Effect of Surface Area of Implant on Bonding Strength between Implant and Bone

Cho,Sung-Am 경북대학교 병원 1998 경북대학교병원의학연구소논문집 Vol.2 No.1

임프란트의 외표면적이 골과의 결합의 정도에 미치는 영향을 알아보기 위하여 10개의 grade Ⅱ 티타늄 임프란트를 사용하여 이를 직경 3미리와 5미리의 2개의 군으로 나누어 10마리의 토끼의 무릎뼈에 삽입하였다. 6주후에 동물들을 희생시키고 회전제거력을 Tohnichi 15-BTG-N Torque gauge Manometer로 측정하여 5㎜직경 그룹의 회전제거력이 3㎜직경 그룹의 회전제거력보다 큰 것을 확인하였다. (p=0.008) The effect of the surface area of implant on degree of osseointegration was investigated by putting the 10 grade-Ⅱ titanium screw implants into 10 isogenic rabbits tibia. Implants were divided in 2 groups into 3㎜ diameter and 5㎜ diameter. After 6 weeks, animals were sacrificed and removal torques were measured with Tonhnichi 15 BTG-N Torque Gauge Manometer. The results were as follows: The removal torques was higher in 5㎜ diameter group than the 3㎜ diameter group.(p=0.008)

The influence of systemically administered oxytocin on the implant-bone interface area: an experimental study in the rabbit

Cho, Sung-Am,Park, Sang-Hun,Cho, Jin-Hyun The Korean Academy of Prosthodonitics 2014 The Journal of Advanced Prosthodontics Vol.6 No.6

PURPOSE. The purpose of this study was to assess the effect of systemically administered oxytocin (OT) on the implant-bone interface by using histomorphometric analysis and the removal torque test. MATERIALS AND METHODS. A total of 10 adult, New Zealand white, female rabbits were used in this experiment. We placed 2 implants (CSM; CSM Implant, Daegu, South Korea) in each distal femoral metaphysis on both the right and left sides; the implants on both sides were placed 10 mm apart. In each rabbit, 1 implant was prepared for histomorphometric analysis and the other 3 were prepared for the removal torque test (RT). The animals received intramuscular injections of either saline (control group; 0.15 M NaCl) or OT (experimental group; $200{\mu}g/rabbit$). The injections were initiated on Day 3 following the implant surgery and were continued for 4 subsequent weeks; the injections were administered twice per day (at a 12-h interval), for 2 days per week. RESULTS. While no statistically significant difference was observed between the two groups (P=.787), the control group had stronger removal torque values. The serum OT concentration (ELISA value) was higher in the OT-treated group, although no statistically significant difference was found. Further, the histomorphometric parameter (bone-to-implant contact [BIC], inter-thread bone, and peri-implant bone) values were higher in the experimental group, but the differences were not significant. CONCLUSION. We postulate that OT supplementation via intramuscular injection weakly contributes to the bone response at the implant-bone interface in rabbits. Therefore, higher concentrations or more frequent administration of OT may be required for a greater bone response to the implant. Further studies analyzing these aspects are needed.