순환 석회화전처리가 Ti-6Al-4V 합금제 교정용 미니스크류의 생체활성도에 미치는 영향

박제혁,황조연,원은규,김연우,양규리,전우용,이민호,배태성 대한치과재료학회 2021 대한치과재료학회지 Vol.48 No.4

This study was performed to evaluate the effect of cyclic precalcification treatment on the improvement of bioactivity of Ti-6Al-4V mini-screws. The cutted plate-shaped specimens of 10 mm × 10 mm dimensions, and a mini-screw with a diameter of 1.6 mm × 6.0 mm in length were used. Anodic oxidation treatment was carried out in a glycerol electrolyte solution containing 20 wt% H2O and 1.5 wt% NH4F. Voltage of 20 V with current density of 20 mA/cm2 was applied for 1 hour to form a nanotube TiO2 layer. Afterwards, to improve the bioactivity, specimens were immersed in 0.5 vol% silica aqueous solution at 37 ℃ for 5 minutes, and then cyclic precalcification treatment with 0.05 M NH4H2PO4 and 0.01 M Ca(OH)2 solution at 90 ℃ was repeated with 20 times. Based on surface treatment the experimental groups were divided into three groups, namely untreated group (UT), anodized and heat-treated group (AH), and anodized, silica-treated, cyclic precalcified and heat-treated group (ASPH). There were TiO2 nanotubes completely self-aligned and formed in a dense structure on the surface after anodic oxidation treatment. A fine granular cluster layer of hydroxyapatite and octacalcium phosphate were formed on the surface after the cyclic precalcification treatment. As a result of immersion test in the simulated body fluid (SBF), bioactivity was confirmed to be improved by the precipitation of protrusions appearing at the initial stage of formation of hydroxyapatite. 본 연구는 기계적으로 유지되는 생체불활성의 Ti-6Al-4V 합금제 교정용 미니스크류에 생체활성을 부여하기 위한 기초적인 자료를 얻기 위해 시행되었다. 20 × 10 × 1 mm 크기로 절단한 Ti-6Al-4V ELI 합금으로 판상 시편과 교정용 미니스크류를 제작한 다음 20 wt% H2O 및 1.5 wt% NH4F를 함유하는 글리세롤 전해액에서 20 V 전압을 1시간 동안 인가하여 나노튜브 TiO2 층을 형성하였다. 그 후, 생체 활성을 개선하기 위해 시편을 37 ℃ 0.5 vol% 실리카 수용액에 5분동안 침지하고서 90°C 0.05 M NH4H2PO4와 0.01 M Ca(OH)2 용액에서 침지주기 1분으로 20회 순환 석회화전처리를 시행한 다음 유사체액에 1일과 3일 동안 침지하고서 인산칼슘의 석출 양상을 조사한 결과, 다음과 같은 결론을 얻었다. 양극산화처리한 표면에 생성된 TiO2 나노튜브들은 속이 비어있는 독립된 튜브구조이고 인접한 튜브들과는 외벽이 부착되어 있었다. 순환 석회화전처리와 열처리한 표면에는 미세한 과립상의 인산칼슘계 석출물들이 덩어리를 이루며 생성되었다. SBF 침지 후 표면에 HA 석출의 초기단계에서 관찰되는 돌기상들이 치밀하게 석출되었으며, X-선 회절분석 결과, HA와 ocatcalcium phosphote로 나타났다. 이상의 결과로 미루어 볼 때, Ti-6Al-4V 합금 제 교정용 미니스크류를 glycerol 수용액에서 전기화학적으로 양극산화처리하여 나노튜브 TiO2 층을 형성한 다음 NH4H2PO4와 0.01 M Ca(OH)2 용액에서 순환 석회화전처리를 하여 인산칼슘 석출을 유도하는 것은 생체활성도 개선의 유효한 수단이 될 수 있을 것으로 생각된다.

RAPID-N을 이용한 국내 지진 발생 시 화학시설 Natech 위험성 평가

박제혁,연응진,이학태,정승호 한국안전학회 2019 한국안전학회지 Vol.34 No.4

Accidents occurring due to natural disasters in chemical process facilities where technologies are concentrated can cause secondary damage. The concept of the relationship between natural disasters and highly intensive technologies has evolved into the Natech (Natural Hazards Triggered Technological Disaster) research. Currently, the number of earthquakes is increasing all over the Korean peninsula. To assess the risk of Natech when an earthquake has occurred in South Korea, the Rapid Natech Risk Assessment Tool (RAPID-N) developed by the European Commission’s Joint Research Center (EC JRC) was used in the present study. The RAPID-N can be used for Natech risk assessment based on mapping and can be utilized for sufficient preparation for reduction of the effects of Natech accidents. A total of 261 chemical facilities actually existing in Pohang were initially analyzed to select eight facilities and the Pohang earthquake that occurred in 2017 was implemented in the RAPID-N utilizing the shake map. High risk areas were selected through Natech risk assessments for the selected eight work places and countermeasures for the areas were suggested. High risk areas exist depending on the location, since the damage influence ranges could be overlapped and each chemical facility has an independent probability of Natech. Therefore, studies on Natech emergency plans and emergency evacuation routes should be actively conducted considering such high risk areas. The present study was conducted to demonstrate the feasibility of Natech risk assessment in South Korea through the RAPID-N. These findings can be used as a reference material to lay a foundation for Natech risk assessment and related policies in South Korea.

시 , 도 역점시책 : 인천직할시 역점시책추진상황

박제혁 대한지방행정공제회 1984 地方行政 Vol.33 No.370

상악 전치부 결손 환자의 수술을 동반한 전략적 교정치료 증례

박제혁(Je-Hyeok Park),전진(Jin Jeon),Zhao Sen,전영미(Young-Mi Jeon),김정기(Jong Ghee Kim) 대한턱관절교합학회 2019 구강회복응용과학지 Vol.35 No.4

JPEG2000 Bit Plane Coder Skipping 방식에 관한 연구

문제혁(Je-Hyuk Moon),박성모(Seong-Mo Park) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.11

In this paper, we studied methods to enhance coding speed of the bit plane coder(BPC) that dominates more than 50% of JPEG2000 arithmetic operations. Skipping methods for BPC. such as sample skipping(SS). group of column skipping (GOCS) and pass skipping(PS), are implemented on Matlab. We compared their performance measuring number of cycle for each BPC operation.

JPEG2000의 DWT-EBCOT간 데이터 전송 및 메모리 구조에 관한 연구

문제혁(Je-Hyuk Moon),손창훈(Chang-Hoon Son),박성모(Seong-Mo Park) 한국멀티미디어학회 2009 한국멀티미디어학회 학술발표논문집 Vol.2009 No.1

In JPEG2000, original image converted to code-block by DWT(Discrete Wavelet Transformation) and Quantization, is compressed finally to bit-stream by EBCOT(Embedded Block Coding with Optimal Truncation). There is a problem that DWT scanning direction differ from EBCOT scanning direction in image data transfer. The difference of scanning direction between DWT and EBCOT causes additional operations or memory access. In this paper, we studied for image data transfer between DWT and EBCOT and proposed efficient memory organization to solve the problem.

만성 C형 간염 환자에서 페그인터페론 알파2a와 리바비린 병합 치료중 발생한 벨마비 1예

김일환,장제혁,유충헌,최규남,고정해,김윤정,서광원,김지현,박성재,박은택,이연재,이상혁,설상영 인제대학교 2008 仁濟醫學 Vol.29 No.-

페그인터페론과 리바비린 병합요법은 만성 C형 간염의 일차 치료법이다. 저자들은 만성 C형 간염 환자에서 페그인터페론 과 리바비린 병합 요법 중에 발생한 벨마비 1예를 경험하였기에 문헌고찰과 함께 보고하는 바이다. 환자는 5년 전부터 만성 C형 간염을 앓아온 48세 남자이며, PEG-IFN α-2a 135μgm 피하주사 주1회와 하루 1200㎎의 리바비린을 투여하였다. 치료시작 후 9개월째 환자는 오른쪽 안면의 근력약화를 호소하였으며 벨마비로 진단되었다. 페그인터페론과 리바비린 병합요법을 지속하면서 관찰하였다. 환자의 벨마비는 페그인터페론 치료를 중단하지 않았음에도 3개월후 증상이 회복되고 이후 벨마비 재발 없이 현재 경과관찰 중이다. 만성 C형 간염에서 페그인터페론과 리바비린 병합 요법시 벨마비의 발생 가능성을 염두에 두어야 하겠다. A Case of Bell's Palsy Associated with Combination Therapy of Pegylated Interferon Alfa-2a (PEG-IFN) and Ribavirin for Chronic Hepatitis C Virus Infection Pegylated interferon alfa(PEG-IFN α) and ribavirin therapy is the first line treatment for chronic hepatitis C. Mild complications of the therapy are common, but more serious complications are rare. We report here a case of Bell's palsy that occurred in a patient with chronic hepatitis C virus infection during combination therapy of PEG-IFN α-2a and ribavirin. The patient was 49-year-old man with chronic hepatitis C (genotype 1b) for 8 years. He had compensated liver cirrhosis with splenomegaly. Therapy with PEG-IFN α- 2a 135mcg/week and ribavirin 1200mg/day was initiated. After 9 months of the therapy, the patient showed a loss of muscular tone on the right side of his face. A diagnosis of Bell's palsy was made. The Bell's palsy resolved over 3 months despite continuation of the combination therapy.

Li[Ni0.3Co0.4Mn0.3]O2 양극물질의 Li-La-Ti-O코팅 효과

이혜진,박보건,유제혁,김석범,박용준,윤수현,김관수 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.10

Li(Ni, Co, Mn)O2 has been known as one of the most promising cathode materials for lithium secondary batteries. However, it has some problems to overcome for commercialization such as inferior rate capability and unstable thermal stability. In order to address these problems, surface modification of cathode materials by coating has been investigated. In the coating techniques, selection of coating material is a key factor of obtaining enhanced properties of cathode materials. In this work, we introduced solid electrolyte (Li-La-Ti-O) as a coating material on the surface of Li[Ni0.3Co0.4Mn0.3]O2 cathode. Specially, we focused on a rate performance of Li-La-Ti-O coated Li[Ni0.3Co0.4Mn0.3]O2 cathode. Both bare and Li-La-Ti-O 2 wt.% coated sample showed similar discharge capacity at 0.5C rate. However, as the increase of charge-discharge rate to 3C, the coated samples displayed better discharge capacity and cyclic performance than those of bare sample.

시뮬레이션 기반 도로 기하 구조와 노면 상태가 주행 안전에 미치는 영향 평가

최지향,김원한,박관,류제혁,원준혁,송재진 한국ITS학회 2021 한국ITS학회 학술대회 Vol.2021 No.04

Li[Ni_0.3Co_0.4Mn_0.3]O₂ 양극물질의 Li-La-Ti-O코팅 효과

이혜진,윤수현,박보건,유제혁,김관수,김석범,박용준,Lee, Hye-Jin,Yun, Su-Hyun,Park, Bo-Gun,Ryu, Jea-Hyeok,Kim, Kwan-Su,Kim, Seuk-Buom,Park, Yong-Joon 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.10

Li(Ni, Co, Mn)$O_2$ has been known as one of the most promising cathode materials for lithium secondary batteries. However, it has some problems to overcome for commercialization such as inferior rate capability and unstable thermal stability. In order to address these problems, surface modification of cathode materials by coating has been investigated. In the coating techniques, selection of coating material is a key factor of obtaining enhanced properties of cathode materials. In this work, we introduced solid electrolyte (Li-La-Ti-O) as a coating material on the surface of $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode. Specially, we focused on a rate performance of Li-La-Ti-O coated $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode. Both bare and Li-La-Ti-O 2 wt.% coated sample showed similar discharge capacity at 0.5C rate. However, as the increase of charge-discharge rate to 3C, the coated samples displayed better discharge capacity and cyclic performance than those of bare sample.