• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.8
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• pp.835-846
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• 2011

In medial opening wedge high tibial osteotomy (OWHTO), researchers have reported critical problems caused by unexpected changes in the tibial posterior-slope angle. This unexpected change can be analyzed, but there is no general solution for cases with an oblique hinge axis and cut plane. We propose a general analysis model for OWHTO. We first evaluate the effects according to variation in the hinge axis and tibial cut plane and then define an ideal correction axis. This ideal axis, called the virtual tibial correction axis, is not on the tibial cut plane in general. In this paper, we also present an evaluation of feasibility of the proposed analysis model.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.25-31
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• 2004

Machinability in metal cutting processes depends on cutting input conditions such as cutting velocity, feed rate, depth of cut, types of work material and tool shape factors. In this study, to assess chip breaking characteristics of a turning process, an equivalent oblique cutting system to this has been established. And the equivalent effective rake angle was determined using side rake angle, back rake angle and side cutting edge angle of the tool. A non-dimensional parameter, Chip breaking index(CB), was used to assess Chip breaking characteristics of chip in conjunction with the equivalent effective rake angle. In case of positive rake angles of the equivalent effective rake, the back rake angle has little effect on the chip breaking characteristics however, in case of negative ones, the side rake angle has some effect on Chip breaking characteristics.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.40-40
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• 2010

산업현장에서는 파이프 또는 탱크류의 1GR용접에서 안정적인 이면비드를 가지는 루트패스 용접을 위해 2~3mm의 루트갭을 띄우고 용접봉 또는 필러와이어를 사용하는 TIG용접을 주로 한다. TIG용접은 고품질의 이면비드가 얻어지며, 용접인자의 제어가 쉽다는 장점이 있어 루트패스 용접에 많이 사용되고 있지만, 루트갭을 띄우면 이면비드는 잘 얻어지지만 용착금속량이 많아지게 되어 제작원가가 상승되고, 또한 소모성 와이어를 사용하는 GMAW에 비해 생산성이 낮다. 따라서, 안정적인 이면비드를 가지면서 생산성이 높은 1GR GMAW 루트패스 용접공정의 개발이 요구되지만, 이 경우도 루트갭이 2~3mm로 정해져 있으면 Fit-up공정에서 공수가 많이 필요하므로 근본적으로 루트갭이 없는 그루브에 대한 루트패스 용접이 더 바람직하다. 본 연구에서는 루트면 2.7mm를 가지는 U-그루브의 갭 없는 루트패스 용접에서 안정적인 이면비드가 형성되는 조건을 검토하기 위해 2.7t의 평판에 대하여 경사상진 각을 주고 기초 실험 후, U-그루브 맞대기 용접 실험을 진행하였다. 이 때, 경사상진 각은 용융금속이 중력으로 인해 아크 후방으로 밀리게 되고, 그로 인해 아크가 모재에 직접 닿게 되어 용입이 더 깊게되므로, 이면비드의 형성에 더 유리하다. 두께 2.7t의 연강 시편 2개를 갭 없는 I-그루브 맞대기 이음에서 Ǿ1.2 연강 솔리드 와이어를 사용하여 GMAW용접을 실시하였고, 용접전류, 용접속도, 경사상진 각, 위빙 폭, 위빙 주파수를 변경하여 각 조건에 대한 이면비드를 관찰하였다. 그 결과 경사상진 각 $25^{\circ}$, 전류 200A, 위빙폭 3mm, 위빙주파수 3Hz의 조건에서 안정적인 이면비드를 얻을 수 있었다. 또한, 현장에서 Fit-up중 발생할 수 있는 루트갭의 문제에 대하여 루트갭 1.2mm의 I-그루브 맞대기 용접에서 경사상진 각, 위빙 폭, 위빙 주파수는 갭 없이 실시한 실험에서 얻어진 가장 안정적인 결과를 사용하였고, 용접 전류, 용접 속도를 변경하여 이면비드를 관찰하였다, 그 결과 갭이 없을 때보다 약 80A 낮은 전류 조건인 120A에서 안정적인 이면비드를 얻을 수 있었다. 앞선 실험들을 기초로 하여 U-그루브 맞대기 용접을 실시 하였고, I-그루브 맞대기 용접에서 사용한 조건들과 유사한 용접 전류, 용접 속도에서 안정적인 이면비드를 얻을 수 있었다.

• The korean journal of orthodontics
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• v.34 no.2 s.103
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• pp.109-119
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• 2004

This study aimed at investigating the skeletal, dentoalveolar, and soft tissue changes of Class III malocclusion cases treated by second molar extraction. The lateral cephalograms of 15 subjects with moderate Class III malocclusion by average ANB $-1.4^{\circ}\;and\;IMPA\;85^{\circ}$ were traced and the computerized superimposition of average craniofacial change was made. The data was gathered and statistically analyzed. The results were as follows: 1 Lower anterior facial height/anterior facial height increased by 0.6%(P<0.01), mandibular plane increased by $1.5^{\circ}$(P<0.05). 2. There was a slightly downward & backward rotation of the mandible. 3. Lower first molar tipped distally by 4.nm(P<0.001), lower anterior teeth lingually tipped by $3.2^{\circ}$(P<0.05). 4. Retracted lower lip improved facial profile. This study may suggest that second molar extraction could be effective for a moderate Class III malocclusion to make distalization of the lower first molar easier and avoid severe lingual tipping of the lower incisor, if the lower third molar has a normal shape, good direction of eruption and adequate time for lower second molar extraction

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.327-330
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• 2006

Numerical study on the passive control of the oblique shock wave/turbulent boundary-layer interaction control utilizing slotted plates over a cavity has been carried out. Numerical results have been compared with the experimental observations, such as pitot/wall surface pressures and Schlieren flow visualizations, obtained for the same boundary conditions. It was found that the present numerical results shows a good agreement with experimental data. Further, the effect of different slot configurations including various number, location and angle of slots on the characteristics of the interactions are also tested, focusing on the variation of the piot pressure and the boundary-layer characteristics downstream of the interaction and the recirculating mass flux through cavity.

• Journal of the Korean Society of Propulsion Engineers
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• v.11 no.2
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• pp.18-25
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• 2007

Computational study on the passive control of the oblique shock-wave/turbulent boundary-layer interaction utilizing slotted plates over a cavity has been carried out. The numerical boundary layer profile upstream of the interaction follows the compressible turbulent boundary-layer theory reasonably well, and the other results also show good agreements with the experimental observations, such as the wall surface pressures and Schlieren flow visualizations. Further, the effects of various slot configuration including number, location and angle of the slots on the characteristics of the interactions, such as the variation of the total pressures, the boundary-layer characteristics downstream of the interaction and the recirculating mass flux through the slots, are also tested and compared.

• Korean Journal of Cleft Lip And Palate
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• v.7 no.2
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• pp.77-91
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• 2004

본 연구의 목적은 반안면왜소증 환자의 하악골 신장술시 초기 치아골격 특성들 중에서 치료결과의 차이에 기여하는 인자를 찾는 것이다. 치료전의 치아골격 특성, 골신장술의 효과와 그 유지상태를 관찰하기 위하여 골신장술 직전(T0), 직후(T1), 추적 2년후(T2)에 측모와 정모 두부방사선 계측사진을 촬영하여 전후방, 수직치아, 비대칭 항목들을 계측하였다. T2 시기의 계측 결과에 따라서 환자들을 1군(양호군, 10명)과 2군(불량군, 9명)으로 분류하였다. 두 군에서 각 시기와 T0-T1, T1-T2 동안의 변화량의 차이를 Mann-Whitney U test, Wilcoxon signed independent t-test, rank test, ANOVA test를 사용하여 분석하였다. pruzansky type이 골신 장술의 성공과 실패 여부와 관계가 깊게 나타났다. T0 시기에 2군은 1군에 비하여 하악골이 후방위치되었고, 하악지 고경(ramus height)이 짧았고, 하악각(gonial angle)이 컸으며, 이환측 하악지가 내측경사되었고, 이환측으로의 이부변위(chin point deviation)가 크게 나타났다. 1군에서 골신장술의 주요한 효과는 하악지 고경의 증가, 하악골의 전방위치, 하악각의 증가, articular angle의 감소에 따른 하약골의 반시계방향 회전, 이환측의 하악지 경사의 증가, 교합면경사와 이부변위의 개선으로 나타났다. 그러나 2군에서는 골신장술을 시행했을 때 1군에 비하여 하악골이 시계방향으로 회전되었고 하악지 고경의 증가량이 작게 나타났다. T2 시기에 2군에서는 하악골의 반시계방향 회전이 나타났고, 하악지 성장이 일어나지 않았으나, 1군은 반대의 경향을 보였다. 이러한 인자들이 골신장술 결과의 차이에 기여하는 것으로 생각된다.

• The korean journal of orthodontics
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• v.26 no.4
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• pp.401-413
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• 1996

Facial vertical dyscrepancies is decided on the relationship between the anterior vertical facial height and posterior vertical facial height. Thus this study was conducted to determine the factors that affect the FHI, and classify the Class II div.1, malocclusion, which success is dependent on the vertical control according to the FHI, which is the ratio of antero-inferior facial height, posterio-inferior facial height ratio, and to use this as a guideline for treatment. Angle between palatal plane and Mandibular plane were in the order of RH, ID. Thus showing that interrelated angle was more inportant than the independent angle of both, palatal plane and Mandibular plane. The tendency of Cl II div.1. Malocclusion according to FHI, showed the Low group to have Mx. protrusion, prominent development of Mn. ramus, and the Mn. body length and ant. post. position was normal. The Normo group showed slight protrusion of the Maxilla,. The development of the ramus was less than normal and the Mn. was in a slight retruded position. The High group showed the Mx. in a normal position, the development of the Mn. ramus and body was the lowest, and the Mn. was in a posterior position. In observation of the factors affecting the FHI between each groups of Cl II div.l, malocclusion; In the Low group the MP- PP angle was very small, the ID was smililar to the normal group, but the RH was very large thus the FHI was increased. In the Normo group, the PP-MP angle was normal, ID was slightly smaller than the normal group and the RH was slightly smaller than the normal group, thus maintaining a normal FHI ratio. In the High group the PP-MP angle was very large, the ID was similar to the normal group, but the RH was smaller than the normal group thus the FHI was small.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.205-218
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• 1996

A given facial type can be considered as a syndrome in which various features are aggregated, so a single parameter is not sufficient to accurately identify a given facial type. This study was designed to identify & characterize the skeletal types that blend under the headline-'Cl III,deepbite'. Cephalograms of thirty-four untreated mixed dentition patients, selected mainly on the basis of clinical impression of Cl III with reduced lower face heights were studied. The following conclusion can be drawn. 1. Cl III malocclusion with reduced lower face height could be classified into three types. 2. Subtype 1 was identified by the following features : strong ramus, more anteriorly positioned upper molars without alveolar hypoplasia, acutely reduced Mn. plane angle. 3. Subtype 2 was characterized by a short ramus, sharply reduced postrior alveolar height, and normal Mn. plane angle. In general, this type had hypoplasia tendency in the vertical dimension. 4. In subtype 3, the AUFH occupying more percentage than ALFH was a outstanding feature. Ramal height was in normal range, alveolar hypoplasia and slightly reduced Mn. plane angle was observed. 5. The features of the subtypes were reflected in certain indices, which can be regarded as discriminative index. LAFH: if reduced, regardless of subtypes, indicates reduced lower ant. face height consistently. FHR: when this ratio is increased, it indicates subtype 1. FHI: when this ratio is in normal range, it indicates subtype 2. FPI: if reduced greatly, it indicates subtype 3.

• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.543-554
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• 1995

This paper describes the improvement of driving stability and the control system for INMEL-VII which is motorized manual wheelchair to satisfy requirements of the disabled The INMEL-VI was based on high maneuverability of the omnidirection drive and safety But the results of field tests about two years showed some problems to the disabled in daily life such as driving stability, Pm switching noise, and rotation of motor without driving command on negative slope. To solve the problems due to an increased DC motor power and applied to direct connection method in INMEL- VII. It improved the driving circuits and set switching frequency to 5KHz to eliminate the switching noise caused by PWM control of DC motor, As compare with the INMEL-VI, INMEL-VII is improved in driving stability by transfer the weight center to forward. The results of field testing proved the improvement of the driving stability and software algorithm It has been estimated to have a hlgh practical use for powered walking aids to the disabled's daily life.