Titanium plasma sprayed implant에 관한 여러가지 기계적 표면처리방법이 implant표면조도에 미치는 영향

유현석,박재완,서조영,Yu, Hyeon-Seok,Park, Jae-Wan,Suh, Jo-Young 대한치주과학회 1993 Journal of Periodontal & Implant Science Vol.23 No.3

실패한 임프란트를 구강내에 유지하기 위하여는 임프란트 매식체의 표면을 처치하여 세균독소를 제거하구 주위의 연, 경조직에 적합한 표면 구조를 만들어 주어야 한다. 이에 본 연구에서는 임프란트 매식체 표면을 high speed diamond bur, low speed diamond bur, stone, rubber point, Jetpolisher로 처치하여 가장 평활한 표면을 만들 수 있는 방법을 알아 보았다. 조도측정기를 이용하여 표면의 최대높이값을 측정한 결과 high speed diamond bur, rubber point, Jetpolisher를 사용한 시편의 최대높이값의 평균은 $7.77{\mu}m$였고, low speed diamond bur, rubber point, Jetpolisher를 사용한 경우에는 $8.44{\mu}m$를 보였다. Stone, rubber point, Jetpolisher를 사용한 경우 $6.24{\mu}m$로 가장 평활한 표면을 보였다. 이러한 수치들은 제거하지 않은 TPS(titanium plasma sprayed)면의 $24.43{\mu}m$에 비하여는 낮은 수치를 보였다. 주사전자현미경으로 관찰 하였을 때 high speed diamond bur, rubber point, Jetpolisher를 사용한 군에서는 TPS 입자들이 부분적으로 남아있었으나 이 입자들은 그 높이가 원래의 TPS에 비하여는 상당히 감소되어 있었다. Low speed diamond bur, rubber point, Jetpolisher를 사용한 시편에서는 전 표면에 걸쳐 TPS가 남아있는 거친 표면 구조를 보였다. Stone, rubber point, Jetpolisher를 사용한 시편은 대부분의 TPS가 제거되어 titanium이 노출되어 있었고, titanium 금속에 stone에 의한 흠들이 보였으나 일부분에서는 TPS가 남아있어 제조회사에서 만들어진 평활한 표면에 비해서는 거친 양상을 보였다. For maintenance of an ailing or failed implant it is essential to treat the implant fixture surface so as to remove bacterial endotoxin and make a surface tolerated by surrounding soft and hard tissue. Thus in this study the method that makes the smoothest surface treated with a high speed diamond bur, a low speed diamond bur, a stone, a rubber point or Jetpolisher was studied. With the profilomenter a mean value of $R_{max}$ was measured. The hight speed diamond, the rubber point and the Jetpolisher showed a mean $R_{max}\;7.77{\mu}m$. The low speed diamond bur, the rubber, point and the Jetolisher made a mean value of $R_{max}\;8.44{\mu}m$. The stone, the rubber point and the Jetolisher showed the smoothest surfaces with a mean value of $R_{max}\;6.24{\mu}m$. TPS (titanium plasma sprayed) areas showed a mean vlaue of $R_{max}\;24.42{\mu}m$, and the smooth surfaced titanium disc manufactured by the company (IMZ, Germany) shows a mean value of $R_{max}\;3.00{\mu}m$. Under the SEM examination the disc treated with a high speed diamond bur, a rubber point and a Jetpolisher showed partially remaining TPS particles, but the height of these particles were reduced remarkably compared with those of the original TPS. The disc treated with a low speed diamond bur, a rubber point and a Jetpolisher showed a rough topography with remaining TPS on the entire surface. A stone, a rubber point and a Jetpolisher removed almost TPS and the bulk titanium metal was exposed and some scratches were made by the stone. All treated discs were revealed as rougher than the smooth surface disc manufactured by the company. An untreated TPS disc shows a very irregular surface and a $40{\mu}m$ height of the plasma sprayed areas.

천연가스의 연소속도 측정에 관한 실험적 연구

유현석,한정옥,방효선,Yu, Hyeon-Seok,Han, Jeong-Ok,Bang, Hyo-Seon 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.2

Static and non-static flame methods were used to measure the laminar burning velocity of methane, ethane and natural gas. The flame slot angle and velocity of unburned gas mixture were determined by Schlieren method and LDV, respectively, for static flame. The diameter of nozzle was selected as 11 mm. The experimental results containing the stretch effect showed that the maximum burning velocities were 41.5 for natural gas, 40.8 for methane and 43.4 cm/sec for ethane on equivalence ratio of 1.1. Constant volume combustion chamber was also used for non-static flame. The propagation process of flame front was visualized by high speed camera during constant pressure. The maximum burning velocity of natural gas was determined as 42.1 cm/sec on equivalence ratio of 1.15.

폴리에스테르 용융방사시 등온영역이 역학적 성질에 미치는 영향

유연춘,유현석,Yu, Yeon-Chun,Yu, Hyeon-Seok 한국섬유공학회 1997 한국섬유공학회지 Vol.34 No.4

Effects of isothermal temperature on mechanical properties of polyester filament during melt spin-draw system were studied. Tenacity decreased, but elongation increased with the increase of isothermal temperature from 130℃ to 250℃. Velc showed minimum value at isothermal temperature of 210℃. Young's modulus and crystallinity as a function of isothermal temperature showed a similar pattern, in which Young's modulus and crystallinity increased to 127 Eld and 0.455, respectively, as the isothermal temperature increased, and then decreased. The maximum values in both cases appeared at the isothermal temperature of 190℃ due to the fastest crystallization at this temperature. Apparent crystallite size in the b-axis direction was larger than that related to the a-axis irrespective of isothermal temperature. Apparent crystallite size in the b-axis direction had almost the same values 58 A as a function of isothermal temperature from 150℃ to 250℃.

산소부화된 자유롭게 전파하는 CH₄/O₂/N₂예혼합화염의 화염구조

이기용,남태형,유현석,최동수,Lee, Gi-Yong,Nam, Tae-Hyeong,Yu, Hyeon-Seok,Choe, Dong-Su 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.4

Numerical simulations of freely propagating flames burning stoichiometric CH$_4$/O$_2$/$N_2$mixtures are performed at atmospheric pressure in order to understand the effect of the $O_2$enrichment level on CH$_4$/Air flame. A chemical kinetic mechanism is employed, the adopted scheme involving 54 gas-phase species and 632 forward reactions. The calculated flame speeds are compared with the experiments for the flames established at several $O_2$enrichment level, the results of which is in excellent agreement. As a result of the increased $O_2$enrichment level from 0.21 to 1, the mole fraction of CO in the burred gas is increased. The flame speed and the temperature in the burned gas are also increased, but the thickness of the flame is severely shrunken in the preheat region. The maximum of the calculated EINO is obtained around 0.6 and 0.7 of the $O_2$enrichment level in cases of flames for fuel-lean mixtures.

Commando 手術法에 依한 唾液腺 透明細胞癌腫의 治驗例

Kim Yong Kack(金容珏),Chung Boong Hee(鄭朋喜),Yu Hyeon Seok(劉顯碩) 대한구강악안면외과학회 1988 대한구강악안면외과학회지 Vol.14 No.1

The clear cell carcinoma of salivary gland origin is a recently recognized lesion and has a low grade malignancy. It is found primarily in the major salivary gland, especially the parotid. But it may, however, be found in intraoral sites. This article presents a case of clear cell carcinoma which was confirmed with the aid of electron microscopic findings and treated radically via modified commando operation. The lesion occurred in the right retromolar pad area of a 48-year old man and it invaded underlying bone resulting in radiolucent destruction in mandible. This cleai cell carcinoma was found to be non-mucinous, glycogen-deficient, monomorphic, and originated from minor salivary gland in the intraoral site. To maintain the continuity of the mandible the patient underwent modified commando operation i.e. the composite resection of the tumor mass, marginal mandible and regional lymph nodes by functional neck dissection. After operation, follow up studies revealed good function and no remarkable postoperative complications.

표재 이하선 적출술에 의한 이하선 점액류상피암종의 치험례

김용각(Yong Kack Kim),정붕희(Boong Hee Chung),유현석(Hyeon Seok Yu),곽재근(Jae Keun Kwak) 대한구강악안면외과학회 1989 대한구강악안면외과학회지 Vol.15 No.2

Like most parotid neoplasms, mucoepidermoid tumors are generally considered not to be radiosensitive and the primary approach is surgical. We should be preserve the facial nerve during surgical approach in the parotid gland. This case showed mucoepidermoid tumor in the right parotid gland which occurred in a 53-year-old female. This presented Grade Ⅰ tumor. Therefore, the treatment was performed with superficial lobectomy by four techniques for approaching the facial nerve ; anterior, superior, posterior, and inferior. But transient paresis of the facial nerve occurred in this case, it was recovered completely. And there is no evidence of disease, she is satisfied in function and esthetic aspect.

상악골 악성종양의 외과적 절제후 안면 보철물을 이용한 치험례

김용각(Yong Kack Kim),정붕희(Boong Hee Chung),유현석(Hyeon Seok Yu),곽재근(Jae Kean Kwak) 대한구강악안면외과학회 1990 대한구강악안면외과학회지 Vol.16 No.1

The current treatment Philosophy for maxillary cancer is an excision of tumor in combination with X-ray radiation. Orbital exenteration is required when invasion of the orbit has occurred from a maxillary cancer. Orbitomaxillary resection results in functional and esthetic problems. There are many limitation to the surgical reconstruction after radiation therapy. And cosmetic results are less satisfactory when surgical reconstruction follows orbitomaxillary resection. This article reports squamous cell carcinoma of maxilla which occurred in a 52-year-old man. PNS CT showed soft mass occupying entire Lt. maxillary antrum, invading the ethmoid air cell and medial aspect of Lt. orbit. This presented the stage Ⅲ(T₃N₀M₀) malignacy. Agter induction chemotherapy, total maxillectomy with orbital exenteration in combination with radiation therapy was performed. Facial prosthesis with prosthetic eye was fabricated with silicone. Esthetic and functional results have been good. And there is no sign of recurrence for the present. But he must be followed for life.

구강저에 발생한 단독형 신경섬유종

김용각,유현석,곽재근,김규영,정붕희 大韓顎顔面成形再建外科學會 1990 Maxillofacial Plastic Reconstructive Surgery Vol.12 No.3

Benign neural sheath neoplasms are not common in the maxillofacial region. These lesions can occur as solitary tumors, or they can affect many sites in the form of multiple neurofibromatosis. A solitary neurofibroma is seldom undergo sarcomatous transformation, since solitary neurofibroma is relatively radioresistant and its recurrence rate seems to be low, the treatment of choice is surgical excision. This case showed a solitary neurofibroma in the left side of the floor of mouth which occurred in a 33 - year -old female. The tumor was excised. And there is no evidence of disease. She is satisfied in function and esthetic aspect.