임플란트 hexagon 높이에 따른 임플란트와 주위 조직의 응력분포 평가

박성재,김주현,김소연,윤미정,고석민,허중보 대한치과보철학회 2012 대한치과보철학회지 Vol.50 No.1

PURPOSE. To analyze the stress distribution of the implant and its supporting structures through 3D finite elements analysis for implants with different hexagon heights and to make the assessment of the mechanical stability and the effect of the elements. MATERIALS AND METHODS. Infinite elements modeling with CAD data was designed. The modeling was done as follows; an external connection type ∅4.0 mm×11.5 mm OsstemUSII (Osstem Co., Pusan, Korea) implant system was used, the implant was planted in the mandibular first molar region with appropriate prosthetic restoration, the hexagon (implant fixture’s external connection) height of 0.0, 0.7, 1.2, and 1.5 mm were applied. ABAQUS 6.4 (ABAQUS, Inc., Providence, USA) was used to calculate the stress value. The force distribution via color distribution on each experimental group’s implant fixture and titanium screw was studied based on the equivalent stress (von Mises stress). The maximum stress level of each element (crown, implant screw, implant fixture, cortical bone and cancellous bone) was compared. RESULTS. The hexagonal height of the implant with external connection had an influence on the stress distribution of the fixture, screw and upper prosthesis and the surrounding supporting bone. As the hexagon height increased, the stress was well distributed and there was a decrease in the maximum stress value. If the height of the hexagon reached over 1.2 mm, there was no significant influence on the stress distribution. CONCLUSION. For implants with external connections, a hexagon is vital for stress distribution. As the height of the hexagon increased, the more effective stress distribution was observed. 연구 목적: 본 연구는 hexagon 높이에 따른 임플란트 각 부위와 주위 지지조직의 응력분포를 3차원 유한요소 해석을 통해 평가하여 hexagon 높이가 기계적 안정성에 미치는 영향을 평가하고자 시행되었다. 연구 재료 및 방법: 외측 연결 형태의∅L4.0 mm×11.5 mm USII (Osstem Co., Pusan, Korea) 임플란트 시스템을 이용하여 하악 제 1대구치 부위에 임플란트를 식립하여 보철 수복한 경우를 연구 모델로 가정하고 임플란트 고정체의 외측 연결부인 hexagon의 높이를 각각 0.0 mm, 0.7 mm, 1.2 mm, 1.5 mm로 적용한 CAD data를 유한요소 모형화하였다. ABAQUS 6.4 (ABAQUS Inc., Providence, RI, USA)를 이용하여 산출된 응력 값 중에서 등가응력을 기준으로 각 요소(상부 치관, 지대주 나사, 고정체, 치밀골, 해면골)에서 나타나는 최대 응력 값을 비교 하였다. 결과:외측 연결을 갖는 임플란트의 hexagon의 높이는 고정체, 지대주 나사, 상부 보철물 그리고 주위 지지골에 대해 응력 분산에 영향을 주었다. Hexagon의 높이가 증가할 수록 임플란트의 응력 분산은 더 잘 이루어졌으며, 최대 응력 값의 감소를 보였다. Hexagon의 높이가 1.2 mm 이상이 되면 응력 분포에 더 이상 크게 기여하지 않았다. 결론: 외측연결을 갖는 임플란트에서 hexagon은 응력 분산에 필수적인 요소이며 그 높이가 증가할수록 더욱 효과적인 응력의 분산이 나타났다.

골밀도와 임플란트 안정성 변화에 대한 전향적 연구

고석민(Sok-Min Ko),박성재(Seong-Jae Park),이인경(In-Kyung Lee) 대한턱관절교합학회 2013 구강회복응용과학지 Vol.29 No.1

노인요양시설에서의 구강위생관리

고석민(Sok-Min Ko),임순연(Soon-Ryun Lim) 대한치과의사협회 2015 대한치과의사협회지 Vol.53 No.10

흡인성 폐렴의 예방을 위해서는 구강위생관리를 철저하게 실천하는 것이 매우 중요하므로 적절한 관리요령이 병원과 요양시설에 보급되어야 할 것이다. 잘못된 구강위생관리 방법이 행해진다면 그 자체가 흡인성 폐렴의 원인이 될 수 있기 때문이다. 의료 간호의 현장에서 효율적이고 효과적인 구강위생관리를 위해서는 이를 수행할 수 있는 치과의사와 치과위생사의 개입이 필수적이다. 노인요양시설의 치과촉탁의 제도의 시행이 가시화되고 있는 시점에서 우리 치과계에서는 위험성이 적으면서 구강위생과 구강기능을 지킬 수 있는 올바른 방법을 제안해야 하고, 물을 사용하지 않는 전문적 구강위생관리방법이야말로 오연의 위험을 감소시키면서 보다 안전하고 환자에 부담이 적은 전문적 구강위생관리 방법이라 사료된다. 쉽게 실천할 수 있는 방법이므로 앞으로 노인요양시설의 치과촉탁의 제도 시행 시 치과위생사, 치과의사에게 진정으로 도움이 되기를 바란다. In order to prevent aspiration pneumonia, oral hygiene care is important; thus proper tips for oral hygiene care should be distributed among hospitals and care facilities for elderly. Malpractice of oral hygiene itself may cause aspiration pneumonia. For efficient and effective oral hygiene care, engagement of professionals such as dentists or dental hygienists is essential. At the point where necessity of systemized dental professionals°Ø involvement at care facilities for elderly is being emerged, it is important to determine less risky approaches for oral health care tailored to elderly. Among many approaches, oral health care practice without usage of water is considered safe, reducing risk of possibility of aspiration. Since this practice is quite easy to implement, many dental professionals may utilize it when practiced at care facilities for elderly.

상악 중절치 단독 결손의 임플랜트 수복 후 음성 언어 평가

고석민(Ko, Sok-Min),송광엽(Song, Kwang-Yeob),안승근(Ahn, Seung-Geun),박찬운(Park, Charn-Woon) 대한턱관절교합학회 1997 구강회복응용과학지 Vol.13 No.1

Precise Prediction of Optical Performance for Near Infrared Instrument Using Adaptive Fitting Line

Ko, Kyeongyeon,Han, Jeong-Yeol,Nah, Jakyoung,Oh, Heeyoung,Yuk, In-Soo,Park, Chan,Chun, Moo-Young,Oh, Jae Sok,Kim, Kang-Min,Lee, Hanshin,Jeong, Ueejeong,Jaffe, Daniel T. 한국우주과학회 2013 Journal of Astronomy and Space Sciences Vol.30 No.4

Infrared optical systems are operated at low temperature and vacuum (LT-V) condition, whereas the assembly and alignment are performed at room temperature and non-vacuum (RT-NV) condition. The differences in temperature and pressure between assembly/alignment environments and operation environment change the physical characteristics of optical and opto-mechanical parts (e.g., thickness, height, length, curvature, and refractive index), and the resultant optical performance changes accordingly. In this study, using input relay optics (IO), among the components of the Immersion GRating INfrared Spectrograph (IGRINS) which is an infrared spectrograph, a simulation based on the physical information of this optical system and an actual experiment were performed; and optical performances in the RT-NV, RT-V, and LT-V environments were predicted with an accuracy of 0.014±0.007 λ rms WFE, by developing an adaptive fitting line. The developed adaptive fitting line can quantitatively control assembly and alignment processes below λ/70 rms WFE. Therefore, it is expected that the subsequent processes of assembly, alignment, and performance analysis could not be repeated.

상악 총의치 장착 환자 언어의 음향학적 특성 연구

고석민,황병남 한국음성과학회 2001 음성과학 Vol.8 No.4

Speech intelligibility in patients with complete dentures is an important clinical problem depending on the material used. The objective of this study was to investigate the speech of two edentulous subjects fitted with a complete maxillary prosthesis made of two different palatal materials: chrome-cobalt alloy and acrylic resin. Three patients with complete dentures in the experiment group and ten people in the controls groups participated in the experiment. CSL, Visi-Pitch were used to measure speech characteristics. The test words consisted of a simple vowel /e/, meaningless three syllabic words containing fricative, affricated and stops sounds, and sustained fricative sounds /s/ and /??/. The analysis speech parameters were vowel and lateral formants, VOT, sound durations, sound pressure level and fricative frequency. Data analysis was conducted by a series of paired T-test. The findings like the following: (1)Vowel formant one of patients with complete denture is higher than that of the control group (p<0.05), while lateral formant three of patients with complete denture is lower than that of the control group (p<0.01). (2) Patients with complete denture produced lower speech intelligibility with low fricative frequency (/??/) than control group (p<0.0). The speech intelligibility of patients with metal prosthesis was higher than that of those with resin prosthesis (p<0.05). (3) Fricative, lateral and stop sound durations of patients with complete denture were longer than those of the control group (p<0.01 and p<0.05), respectively. Total sound durations of patients with metal prosthesis were similar to that of the control group (p<0.05), while those with resin prosthesis had a shorter duration (p<0.01). This implied that those with metal prosthesis had higher speech intelligibility than those with resin prosthesis. (4) Patients with complete denture had higher sound pressure levels /t/ and /c/ than the control group (p<0.01). However, sound pressure levels for /c/ of patients with metal prosthesis or resin prosthesis was similar to the control group (p<0.05). (5) Patients with complete denture had higher fundamental frequency than the control group (p<0.01).

Detector Mount Design for IGRINS

Jae Sok Oh,Chan Park,Sang-Mok Cha,In-Soo Yuk,Kwijong Park,Kang-Min Kim,Moo-Young Chun,Kyeongyeon Ko,Heeyoung Oh,Ueejeong Jeong,Jakyoung Nah,Hanshin Lee,Daniel T. Jaffe 한국우주과학회 2014 Journal of Astronomy and Space Sciences Vol.31 No.2

The Immersion Grating Infrared Spectrometer (IGRINS) is a near-infrared wide-band high-resolution spectrograph jointly developed by the Korea Astronomy and Space Science Institute and the University of Texas at Austin. IGRINS employs three HAWAII-2RG Focal Plane Array (H2RG FPA) detectors. We present the design and fabrication of the detector mount for the H2RG detector. The detector mount consists of a detector housing, an ASIC housing, a Field Flattener Lens (FFL) mount, and a support base frame. The detector and the ASIC housing should be kept at 65 K and the support base frame at 130 K. Therefore they are thermally isolated by the support made of GFRP material. The detector mount is designed so that it has features of fine adjusting the position of the detector surface in the optical axis and of fine adjusting yaw and pitch angles in order to utilize as an optical system alignment compensator. We optimized the structural stability and thermal characteristics of the mount design using computer-aided 3D modeling and finite element analysis. Based on the structural and thermal analysis, the designed detector mount meets an optical stability tolerance and system thermal requirements. Actual detector mount fabricated based on the design has been installed into the IGRINS cryostat and successfully passed a vacuum test and a cold test.

A 200-V 98.16%-Efficiency Buck LED Driver Using Integrated Current Control to Improve Current Accuracy for Large-Scale Single-String LED Backlighting Applications

Baek-Min Lim,Young-Hun Ko,Yeong-Shin Jang,Ok-Hwan Kwon,Sok-Kyun Han,Sang-Gug Lee Institute of Electrical and Electronics Engineers 2016 IEEE transactions on power electronics Vol. No.

<P>This paper presents an average current mode buck dimmable light-emitting diode (LED) driver for large-scale single-string LED backlighting applications. The proposed integrated current control technique can provide exact current control signals by using an autozeroed integrator to enhance the accuracy of the average current of LEDs while driving a large number of LEDs. Adoption of discontinuous low-side current sensing leads to power loss reduction. Adoption of a fast-settling technique allows the LED driver to enter into the steady state within three switching cycles after the dimming signal is triggered. Implemented in a 0.35-mu m HV CMOS process, the proposed LED driver achieves 1.7% LED current error and 98.16% peak efficiency over an input voltage range of 110 to 200 V while driving 30 to 50 LEDs.</P>

Mechanical design of mounts for IGRINS focal plane array

Jae Sok Oh,Chan Park,Sang-Mok Cha,In-Soo Yuk,Kwijong Park,Kang-Min Kim,Moo-Young Chun,Kyeongyeon Ko,Heeyoung Oh,Ueejeong Jeong,Jakyuong Nah,Hanshin Lee,Michael Pavel,Daniel T. Jaffe 한국천문학회 2014 天文學會報 Vol.39 No.1

Detector Mount Design for IGRINS

Oh, Jae Sok,Park, Chan,Cha, Sang-Mok,Yuk, In-Soo,Park, Kwijong,Kim, Kang-Min,Chun, Moo-Young,Ko, Kyeongyeon,Oh, Heeyoung,Jeong, Ueejeong,Nah, Jakyoung,Lee, Hanshin,Jaffe, Daniel T. The Korean Space Science Society 2014 Journal of Astronomy and Space Sciences Vol.31 No.2

The Immersion Grating Infrared Spectrometer (IGRINS) is a near-infrared wide-band high-resolution spectrograph jointly developed by the Korea Astronomy and Space Science Institute and the University of Texas at Austin. IGRINS employs three HAWAII-2RG Focal Plane Array (H2RG FPA) detectors. We present the design and fabrication of the detector mount for the H2RG detector. The detector mount consists of a detector housing, an ASIC housing, a Field Flattener Lens (FFL) mount, and a support base frame. The detector and the ASIC housing should be kept at 65 K and the support base frame at 130 K. Therefore they are thermally isolated by the support made of GFRP material. The detector mount is designed so that it has features of fine adjusting the position of the detector surface in the optical axis and of fine adjusting yaw and pitch angles in order to utilize as an optical system alignment compensator. We optimized the structural stability and thermal characteristics of the mount design using computer-aided 3D modeling and finite element analysis. Based on the structural and thermal analysis, the designed detector mount meets an optical stability tolerance and system thermal requirements. Actual detector mount fabricated based on the design has been installed into the IGRINS cryostat and successfully passed a vacuum test and a cold test.