• Journal of Biosystems Engineering
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• v.3 no.2
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• pp.34-34
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• 1978

To find out the power tiller's travel and tractive characteristics on the general slope land, the tractive p:nver transmitting system was divided into the internal an,~ external power transmission systems. The performance of power tiller's engine which is the initial unit of internal transmission system was tested. In addition, the mathematical model for the tractive force of driving wheel which is the initial unit of external transmission system, was derived by energy and force balance. An analytical solution of performed for tractive forces was determined by use of the model through the digital computer programme. To justify the reliability of the theoretical value, the draft force was measured by the strain gauge system on the general slope land and compared with theoretical values. The results of the analytical and experimental performance of power tiller on the field may be summarized as follows; (1) The mathematical equation of rolIing resistance was derived as $$Rh=\frac {W_z-AC \[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\] sin\theta_1}} {tan\phi \[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]+\frac{tan\theta_1}{1}$$ and angle of rolling resistance as $$\theta _1 - tan^1\[ \frac {2T(AcrS_0 - T)+\sqrt (T-AcrS_0)^2(2T)^2-4(T^2-W_2^2r^2)\times (T-AcrS_0)^2 W_z^2r^2S_0^2tan^2\phi} {2(T^2-W_z^2r^2)S_0tan\phi}\] $$and the equation of frft force was derived as$$P=(AC+Rtan\phi)\[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]cos\phi_1 ? \frac {W_z ?{AC\[ [1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\)\]sin\phi_1 {tan\phi[1+ \frac{sl}{K} \(\varrho ^{-\frac{sl}{K}-1\]+ \frac {tan\phi_1} { 1} ? W_1sin\alpha $$The slip coefficient K in these equations was fitted to approximately 1. 5 on the level lands and 2 on the slope land. (2) The coefficient of rolling resistance Rn was increased with increasing slip percent 5 and did not influenced by the angle of slope land. The angle of rolling resistance Ol was increasing sinkage Z of driving wheel. The value of Ol was found to be within the limits of Ol =2? "'16?. (3) The vertical weight transfered to power tiller on general slope land can be estim ated by use of th~ derived equation: $$R_pz= \frac {\sum_{i=1}^{4}{W_i}} {l_T} { (l_T-l) cos\alpha cos\beta ? \bar(h) sin \alpha - W_1 cos\alpha cos\beta$$The vertical transfer weight $R_pz$ was decreased with increasing the angle of slope land. The ratio of weight difference of right and left driving wheel on slop eland,$\lambda= \frac { {W_L_Z} - {W_R_Z}} {W_Z} $, was increased from ,$\lambda$=0 to$\lambda$=0.4 with increasing the angle of side slope land ($\beta = 0^\circ~20^\circ) (4) In case of no draft resistance, the difference between the travelling velocities on the level and the slope land was very small to give 0.5m/sec, in which the travelling velocity on the general slope land was decreased in curvilinear trend as the draft load increased. The decreasing rate of travelling velocity by the increase of side slope angle was less than that by the increase of hill slope angle a, (5) Rate of side slip by the side slope angle was defined as $ S_r=\frac {S_s}{l_s} \times$ 100( %), and the rate of side slip of the low travelling velocity was larger than that of the high travelling velocity. (6) Draft forces of power tiller did not affect by the angular velocity of driving wheel, and maximum draft coefficient occurred at slip percent of S=60% and the maximum draft power efficiency occurred at slip percent of S=30%. The maximum draft coefficient occurred at slip percent of S=60% on the side slope land, and the draft coefficent was nearly constant regardless of the side slope angle on the hill slope land. The maximum draft coefficient occurred at slip perecent of S=65% and it was decreased with increasing hill slope angle $\alpha$. The maximum draft power efficiency occurred at S=30 % on the general slope land. Therefore, it would be reasonable to have the draft operation at slip percent of S=30% on the general slope land. (7) The portions of the power supplied by the engine of the power tiller which were used as the source of draft power were 46.7% on the concrete road, 26.7% on the level land, and 13~20%; on the general slope land ($\alpha = O~ 15^\circ ,\beta = 0 ~ 10^\circ$) , respectively. Therefore, it may be desirable to develope the new mechanism of the external pO'wer transmitting system for the general slope land to improved its performance.

• 한국IT서비스학회:학술대회논문집
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• 2003.05a
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• pp.83-94
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• 2003

본 연구는 국내외를 막론하고 SI 기업의 R&D에 대한 학문적 연구가 거의 이루어지지 않은 상태에서, 국내 대형 SI 기업들이 World Class SI로 성장하는데 견인차가 되도록 최초로 SI 기업의 R&D 모델을 제시하고 있다. 현재 날로 치열해 지는 SI 시장환경에 비추어 볼 때 향후 국내 대형 SI 기업들간의 보다 치열한 경쟁은 물론이고 국내외에서 선진 IT 서비스 기업들과 경쟁이 예상된다. 본 연구에서는 국내 대형 SI 기업들이 선진 IT 서비스 기업과의 경쟁에서 살아 남으려면 핵심 경쟁력을 확보해야만 하며, 이에 대한 방안으로 연구개발의 강화를 제시한다. 즉, SI 기업은 R&D를 통해 빠르고 복잡하게 변화하는 IT 기술을 적시에 도입하여 실제 프로젝트에 적용하고, 기존의 기술 및 프로세스의 개선을 통해 생산성을 향상시키며, 궁극적으로는 새로운 서비스 모델 개발을 통해 가치를 창출하는 목적을 달성할 수 있다. 이를 위해 R&D는 부가가치 창출, 미래혁신 주도, 신기술의 검증/평가/확산 담당, 응용기술의 표준획득 및 특허취득, 프로세스와 품질의 일관성과 효율성을 확보하는 역할을 해야 한다. 이러한 R&D 역할을 효율적, 효과적으로 수행하기 위해서는 중앙 R&D와 사업부 R&D를 동시에 운영하는 Hybrid Organization을 제안하고 있다. 또한 국내 대형 SI 기업의 R&D 담당자들과 설문, 인터뷰를 통해 본 연구에서 제시한 모델의 현실 적용성을 살펴보고, 바람직한 R&D 방향성을 제시하고 있다.

• Proceedings of the Safety Management and Science Conference
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• 2011.11a
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• pp.499-506
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• 2011

새로운 IT 환경에서의 변화를 이해하고 경쟁력 있는 클라우드 생태계를 구축하며, 지속가능한 성장을 위한 경쟁정책을 수립하기 위해서는 먼저 우리나라 IT시장의 구조와 그 변화를 정확히 이해하는 것이 필요하다. IT시장의 구조를 이해하기 위한 과거의 선행연구들은 통신시장을 배경으로 수직적 가치사슬 구조를 중심으로 설명한 것이 대부분이었으나, 최근 들어 이슈로 부각하고 있는 클라우드 생태계에 관한 연구는 부족한 실정이다. 본 연구의 목적은 IT시장에서의 클라우드 서비스의 등장에 따른 가치사슬의 변화를 이해하는 것이다. 이를 위해 먼저 기존의 연구 문헌들을 통하여 기업 또는 산업의 공급 구조, 그리고 시장의 생태계를 설명하기 위해 사용하는 기본 틀인 가치사슬의 개념을 정의하고, 이를 통하여 우리나라 IT시장의 가치사슬에 대해, 특히 클라우드 서비스 도입이후의 우리나라 IT시장의 변화를 반영하여 그 구조의 변화를 설명하며, 이를 바탕으로 우리나라 IT시장을 진단하고 시장의 성장을 견인하는 요인들을 파악하도록 한다. 본 연구를 통해 가치사슬 관점에서 IT시장을 이해함으로써, 클라우드 서비스 산업의 경쟁력을 높이고, 향후 클라우드 기반으로 IT생태계를 구축하기 위한 이론적 근거로 활용되길 기대한다.

• Journal of Digital Convergence
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• v.11 no.1
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• pp.89-97
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• 2013

After introducing iPhone in Korea, the craze for iPhone was perceived to be extraordinaire phenomenon and the mobile businesses and researchers paid attention to it. This research purposes to explore more predictive model that explain to adopt the smartphones in Korea. This research show that all of models, TPB, TAM and the integrated model, are significant to explain intention to use the smartphones. TPB explains the higher than TAM, and the integrated model explains the slightly higher than TPB. These results suggest that researcher explore and build the more predictive model that comprise social influences and personal attributes than TAM that is employed broad to study new information communication systems and devices.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.3
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• pp.498-505
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• 2007

Management options for impacted maxillary canines can include (1) continued observation, (2) extraction of the primary canine to aid spontaneous eruption, (3) uncovering and bonding of the impacted tooth and its eruption using orthodontic traction, (4) autotransplantation, and (5) extraction followed by prosthetic replacement. Autotransplantation should be considered when the degree of malposition is too severe to correct by orthodontic alignment. The present report describes the management of an ectopic eruption of the left maxillary canine in an 10-year-old girl. The treatment included the extraction of primary maxillary left canine and the autotransplantation using a Rapid Prototyping model. By using RP model to contour the recipient bone and check for fitting in the prepared socket, the extra-oral time can reduce. The autotransplanted canine showed mobility within normal limit, negative response to percussion and positive to electric pulp test after 6 months.

• Journal of Biosystems Engineering
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• v.14 no.2
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• pp.67-79
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• 1989

This study was conducted to investigate the applicability of true model theory for pull prediction in a powered lugged wheel-soil system and to examine the possibility of using principles of similitude in investigating the dimensions of soil parameters pertinent to a powered lugged wheel-soil system concerning the pull prediction. The following conclusions were derived from the study; 1) The pull of prototype wheels proved to be predicted by those of the model wheels for the range of the dynamic weight tested. The pull curves of models and prototype were respectively very similar in the shape. From this basic knowledge, it was enabled to apply the similitude theory to the performance prediction of the true model. 2) A conditional equation which can be used for the prediction of pull of prototype by model test was derived as follows. $n_f=n_1^{-b}$ where $n_f$ : force scale = $w/w_m$ $n_1$ : length scale = ${\ell}/{\ell}_m$ b : exponent on the length dimension of the soil property ${\alpha}$ The range of the numerical value of b, which was determined by the least square method, was found to be -2.0~-2.6. 3) Considering a relatively wide variation of b values in the pull prediction, b is considered to be a function of many variales. Thus it was concluded that there are several soil properties which are pertinent to the powered lugged-wheel-soil system concerning the pull prediction, and these soil properties may have the different effects on the pull of model and protytype wheels, to give the different dimension on the soil parameters.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.4
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• pp.704-709
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• 2006

Ectopic eruption should be understood as a change in the course of the normal eruption path of a dental bud at any moment in its origin. Transposition is a unique and extreme form of ectopic eruption. The treatment for ectopic eruption and transposition is various from simple observation to surgical exposure and orthodontic traction, according to direction of erupting tooth degree of developing root apex and eruption space etc. Autotransplantation is transplantation of tooth from one area of the mouth to another in the same individual or is moving a eruption tooth into extraction socket or surgically prepared socket, and autotransplantation is considered as a treatment of choice for the ectopic eruption when orthodontic traction is unable or when tooth movement is limited. These cases which were treated with autotransplantation of maxillary lateral incisor and maxillary canine were reported, and good esthetic and functional result were induced.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.5
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• pp.435-443
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• 2018

Most of aged water supply pipes have been replaced by the open cut method. However, this method has some limitations because water pipes, in many cases, are buried together with other underground facilities or are buried in the middle of high-traffic roads or in narrow alleyways where boring machines cannot be used. This research developed a pipe bursting device for small diameter pipes that enables pipe replacement without excavating the ground, by the busting of existing buried pipes followed by the traction and insertion of new pipes. As a results of examining the field applicability of the developed device, PE pipes and PVC pipes required the tractive force of 413.65~665.69 kgf and 457.43~791.35 kgf respectively, plus an additional 30 % tractive force per elbow. The proper number of bursting head was demonstrated that the connection of more than 2 heads could secure a stable bending radius of 15D. The developed device can be improved through field experiments involving various pipe types and pipe diameters, as well as presence/absence of elbow, so as to be utilized regardless of diverse variables according to the conditions of the soils surrounding existing pipes.

• Journal of Biosystems Engineering
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• v.6 no.1
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• pp.1-14
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• 1981

A laboratory model test was carried out with a newly designed model to figure out the vibration characteristics of the vibratory tillage tool according to the method of forced vibration, i.e., horizontally and vertically forced vibrations. The results are summarized as follows: 1. The reduction ratios of the draft force of the vibratory blade were 14.2-42.6% for the case where the vibration was forced parallel to the travelling direction of the blade, and 15-54.5% for the vertically forced vibration. And it was thought that the method of vertically forced vibration was preferable to the reduction of the draft force. 2. The ratio of the draft force of a vibratory blade to that of a static one could be represented as a function of V/At. It was found to be possible to reduce the draft force by taking a lower value of (V/Af) and this meant that the effictiveness of tillage practice using the vibratory system would be limited. 3. The torque to the main rotating shaft to vibrate the model blade increased frequency and amplitude. This tendency varied according to the physical properties of tested soil. In case of horizontally forced vibration, the torque was 8~34% less than in case of vertically forced vibration. 4. With the increase of frequency, the total power requirement increased linearly, and also the portion of oscillating power requirement in the total power tended to increase. The magnitude of the total power requirement was 1.4-13 times greater than that of a static one for the case of horizontal vibration, and 1.5-15 times greater for the case of vertical vibration. It was thought that the horizontal vibration of the blade was preferable to the vertical vibration in view of the power requirement. 5. A linearity was found between the amplitude of moment oscillogram and magnitude of oscillating acceleration. Only positive values of moment occurred when the blade was forced to vibrate vertically, but negative values occurred in rarity in the case of amplitude A3 when the blade was forced to vibrate horizontally.

• Journal of Biosystems Engineering
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• v.27 no.6
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• pp.501-512
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• 2002

Traction performance of off-road vehicles is estimated using slip-traction relationships Two zero condition accepted by ASAE have been used widely to obtain the slip-traction relationships of off-road vehicles. This study was carried out using the soil bin systems to investigate the characteristic of slip-traction curves obtained using two zero conditions defined by ASAE. which are driving and driven zero condition, and to present disadvantage of slip-traction relationship based on two zero conditions of ASAE. The results of this study are summarized as follows : 1. For the driving zero condition, the curve of slip-traction relationship shows some issues. The first question is that the slip is zero when the traction is zero. The second question is that the value of slip is smaller than that of corresponding real slip, as the rolling radius decreased f3r the setting zero condition with driving wheel. 2. For the driven zero condition. slip occurs when the traction is zero, which is more realistic results than driving zero condition. But when a zero condition is set, skid occurs and this result increased the rolling radius of tire and increased slip value f3r the specific traction value of whole slip range. This kind of trend was getting bigger as the soil is softer, or the tire inflation pressure is higher. 3. From the results of this study, it was found that slip-traction relationship obtained by two zero conditions of ASAE is not realistic in estimating the traction performance of off-road vehicles. And also slip-traction relationship obtained for the same experimental condition showed different result in accordance with chosen zero condition,