레이저 클래딩 중첩도가 표면특성에 미치는 영향

이제훈, 서무홍, 한유희 한국레이저가공학회 2000 한국레이저가공학회지 Vol.3 No.1

A 4kW RS840 CO2 laser with a powder auto-feeding apparatus has been used to deposit multiple overlapping tracks of Ni-base superalloy on to low carbon steel. It was found that the surface roughness(turbulence) of an overlapped cladding layer decreased with the increase of the overlapping ratio in an oscillating manner. When the overlapping ratio had values of 0.62, the surface turbulence was lowest. Overlapping ratio offer significant potential for improvement of materials surface properties such as corrosion performance and wear resistance. This paper reports that the overlapping ratio shows best corrosion resistance. The tensile residual stresses generated at the higher overlapping ratio(>0.45) and the element concentration of Fe increased in the surface layer at the lower overlapping ratio(<0.45) may lead to worse corrosion resistance.

SCM 435 구조용강의 플라즈마 질화에 관한 연구

유용주,김인수,이재식 울산대학교 1996 공학연구논문집 Vol.27 No.2

본 연구는 SCM 435 구조용강을 450∼650℃의 온도범위에서 NH₃가스유량을 0.5∼2.1 l/min로 변화시키고, 20∼110분 동안 플라즈마 질화처리하여 강 표면에 생성된 경화층의 두께와 경도 및 조직을 조사하였다. 반응온도 550℃, NH₃1.65 l/min.에서 110분 동안 질화 하였을 경우 생성된 질화층의 두께는 260㎛으로써, 화합물층은 16㎛ 이며, 확산층은 224㎛로 이것이 최대의 질화층이었다. 한편, 반응온도 600℃, NH₃1.65 l/min. 가스유량에서 50분간 반응하였을때 24㎛의 최대 화합물층을 얻을 수 있었다. 또한 화합물층은 450℃와 500℃에서는 r'- Fe₄N-α-Fe로, 550℃에서는 r'-Fe₄N+ε- Fe₃N으로, 600℃이상에서는 r-Fe₄N+α-Fe로 구성되어있는 혼합상이었다. 550℃,NH₃1.65 l/min. 에서 80분 동안 질화처리하였을때 생성된 질화층의 최대 표면경도는 Hv 988이었다. The plasma nitriding of SCM 435 structural steel has been studied at the temperature between 450℃ and 650℃ with gas flow rate of NH₃ 0.5 to 2.1 l/min. for 20 to 110 minutes. The phases of compound layer formed below 500℃ and above 600℃ was mixture of r'-Fe₄N and ε- Fe₂₄N phases, while the phases formed 550 was r' - FeN and - Fe N phases. The hardness of nitrided layer formed at 550℃ with gas flow rate of NH₃ 1.65 l/min. for 80minutes was Hv 988. The thickness of nitrided layer formed at 550℃ with gas flow rate of NH 1.65 l/min. for 110minutes was 260㎛. The nitriede layer was composed of 16㎛ compound layer and 244㎛ diffusion layer.

탄소환원에 의한 Zircon으로 부터 고순도 Zirconia 제조에 관한 연구

유용주,이재식 울산대학교 1991 공학연구논문집 Vol.22 No.2

감압하에서 지르콘사를 탄소환원하므로 지르코니아의 고순도화에 대한 연구를 하였다. 지르콘과 탄소의 혼합물을 1 Torr의 진공로 중에서 가열함으로써, 지르콘 중의 SiO₂는 SiO(g)로 제거되었으며, 이 SiO(g)는 로의 낮은 온도 구역에서 미세한 백색 무정형 분말인 SiO(s)로 응축되었다. 생성된 지르코니아에는 미량의 탄소, ZrO 그리고 ZrC등이 존재하였으나, 공기중에서 산화 반응후에는 지르코니아 단일상으로 되었다. 단일상 지르코니아는 1500℃, C/SiO₂몰비 1.0 일때 SiO₂의 함유량이 가장 작았다. 이러한 공정의 반응 생성물은 XRD, SEM-EDX 및 습식방법 등에 의해서 분석하였으며, 지르코니아 분말의 순도는 99.8%이었고 결정구조는 단사정이었다. A production technics of high-purity ZrO₂ powder from zircon (ZrO₂· SiO₂) were investigated by carbothermic reduction under reduced pressure. The mixture of zircon and carbon was heated in the range of 1200℃ to 1500℃ in vaccum furnace under the condition of 1 Torr. The reaction product for the process was examined by XRD, SEM-EDX, and chemical analysis. By this techniques, the SiO₂ in zircon was removed as SiO(g). The generation of SiO(g) from a Zircon/Carbon mixture at high temperature to was greatly enchanced by reduction of pressure compared to atmospheric. Zirconia powder contaminated with a small amount of carbon, ZrO, and ZrC was obtained before oxidation reaction. Single-phase ZrO₂ was obtained after oxidation reaction of Zirconia powder when the the C/SiO₂ mole ration in the Zircon/Carbon mixture was 0.5∼2.0. The SiO₂content in ZrO₂ powder was minimized at a C/SiO₂ ratio of about 1.0. The monoclinic phase zirconia powder with a high purity of 99.8% and fine grain size was obtained. The SiO(g) generated in the process condensed as a fine white amorphous powder in the low-temperature zone of the vaccum furnace, having an ultrafine grain size.

朝鮮時代 맑은 장국의 分析的 考察

柳載榮,李孝枝 漢陽大學校 韓國生活科學硏究所 1988 韓國 生活 科學 硏究 Vol.- No.6

The results that are derived from analysis and study of the etymology of Kug (clear soup), the kinds of Kug, the change of how to cook it, through the cook books which were published in Yi dynasty are as followings. 1.There were 41 kinds of clear soup. 2.Kug was called Gang, Whag, Tang. The explanation of Gang and Tang has many differences in the books. Whag: was the name of hug that was made of meat, fish, poultry etc. The name of Kug was first used in the Si-eu-jean-seo which was published in 18th centry. 3.The materials of clear soup were meat, poultry, crab, seaweed, fish, shellfish, mushroom, pine nut, chestnut, beancurd, egg, corn-starch, wheat flour, vegetables etc. Seasoning were soysauce, salt, ginger, green onion, seasame oil, salad oil, seasame salt, pepper, super, garlic, vinegar and red pepper etc. 4.The solid stuffs in clear soup were meat, wheat flour-coated fish, thicken soupstock.

비골건의 급성 외상성 아탈구증 : 2예보고

이준영,유재원 朝鮮大學校 附設 醫學硏究所 2003 The Medical Journal of Chosun University Vol.28 No.2

Acute subluxation of the peroneal tendon is an uncommon injury that is predominantly associated with a trauma. Traumatic peroneal tendon subluxation is an uncommon cause of ankle pain. As a result, the diagnosis is often delayed. Traumatic subluxation of peroneal tendon over the lateral malleolus caused by sudden, forceful dorsiflexion of the foot accompanied by a powerful contraction of the peroneal muscles. Numerous surgical techniques have been described for chronic peroneal subluxation or dislocation. But Acute cases has few reports. Authors experienced two cases of acute subluxation of peroneal tendon which were treated simple primary repair of superior peroneal retinaculum with good results.

마이크로 펄스 플라즈마 질화법에 의한 선박엔진용 부품의 표면경화에 관한 연구

이재식,유용주 울산대학교 1996 공학연구논문집 Vol.27 No.2

본 연구는 마이크로 펄스 플라즈마 질화처리한 FCD60, S53C, SCM440강재를 고주파 유도경화 열처리한 동일 강재와의 비교분석을 통해 강 표면에 생성된 경화층의 두께와 경도 및 조직을 조사하고 마모시험을 행하였다. Hv550의 유효경도를 갖는 경화깊이는 마이크로 펄스 플라즈마 질화의 경우 FCD60, S53C, SCM440에서 각각 30㎛,25㎛,25㎛이었고, 고주파 유도경화 열처리는 각각 1.4mm이었다. 경화층의 XRD분석결과 마이크로 펄스 플라즈마 질화의 경우 FCD60과 S53C는 주로 r'- Fe₄N, SCM440은 r' - Fe₄N과 ε- Fe₃N의 혼합상이 생성되었으며, 고주파 유더경화 열처리된 경화층은 α- Fe로 모재와 같았다. 또한, 마모시험결과 상온에서는 고주파 유도경화 열처리에 의해 생성된 경화층이 내마모성이 좋으나, 고온(150℃)과 윤활상태에서는 마이크로 펄스 플라즈마 질화처리하에 의하여 생성된 질화층의 내마모성이 우수하였다. The case hardening of FCD60, S53C and SCM440 by micro-pulse plasma nitriding and high frequency induction heat treatment was invesigated. The effective case depth (of which hardeness is over Hv550) of FCD60, S53C and SCM440 nitrided by micro-;ulse plasma method was 30, 25 and 25㎛, respectively. XRE analysis of nitrided layer, showed that mixture of r' - Fe₄N and ε- Fe₃N phases formed on SCM440, r' -Fe₄N single phase formed on S53C and FCD60. In case of hihh frequency induction heat treatment, hardened layer was α - Fe single phase. The hardened hayer formed by high frequency induction heat treatment was more resistant to wear than nitrided layer at room temperature, however nitrided layer by micro-pulse plasma nitriding was more resistant to wear than induction hardened layer at high temperature and lubricated condition.

좌측흉수로 발현된 Boerhaave 증후군 1예

이준,변유미,조민근,조주연,원경준,김영대,박찬국,김만우,유재근,서홍주,이석기 朝鮮大學校 附設 醫學硏究所 2008 The Medical Journal of Chosun University Vol.33 No.2

구토 후 발생한 토혈을 주소로 내원한 환자에서 좌측 늑막 삼출 동반 시 식도 파열의 가능성을 고려하여 흉수 천자 및 지속적인 흉부 단순 촬영의 추적관찰이 필요하며 식도 파열이 배제된 후 환자의 생체 징후 및 토혈 양을 파악하여 내시경 검사 시기를 신중히 결정하는 것이 좋을 것으로 생각된다. 본 증례는 토혈을 주소로 내원하여 Mallory-Weiss 증후군 의심 하에 내시경을 통한 치료 시행 후 추적 관찰에 의해 진단된 Boerhaave 증후군을 경험하였기에 보고하는 바이다. Boerhaave's syndrome is a spontaneous perforation of the esophagus most commonly resulting from a sudden increase in intraesophageal pressure combined with negative intrathoracic pressure caused by straining or vomiting. Surgery should generally be performed within 24 hours because mortality approached 30 to 50 percent in which surgery was delayed. Therefore, early diagnosis and prompt surgical repair are critical for survival. We have experienced a case of Boerhaave's syndrome in a patient presenting with hematemesis with left pleural effusion without any signs or symptoms of pneumomediastinum or pneumothorax.

운동전·후 淸暑益氣湯 투여방법이 2,000m 달리기시 선수들의 운동피로회복에 미치는 영향

유종만,이규성,강명신,오재근,최용어 韓國體育大學校附屬 體育科學硏究所 1994 韓國體育大學校附屬 體育科學硏究所論文集 Vol.13 No.1

The purpose of this study was to investigate the effects of two different chung-seo-ik-gi-tang administration types on fatigue induced during 2,000 m running in 12 healthy-male elite boxer. All subjects were divided randomly with two groups, Pre-administration Group(A: N=7) and Pre- and Post-administration Group(B: N=7) and performed 2,000 m maximal running. The blood samples were collected from antecubital vein by 10ml syranges(6ml/each) at before exercise, immediately after exhaustion, recover-10 min, recover-20 min and recover-30 min. These samples were used to analyze for the level of glucose, lactate, TG, LDH, pH, HCO₃?, Na??, K??. The statistically analyzed results of various blood parameters were summarized as follow, 1. Plasma glucose were not showed significant difference between two groups. but glucose lwvel at post-exercise and rest-30 min in B group wes significantly decreased. 2. Lactate accumulation in B group was significantly decreased at post-exercise and rest-30 min.. And lactate level at rest-30 min. was showed significant difference between two gruops. 3. Serum LDH response to 2,000 m running at post-exercise and recovary periods was showed significant changes in B group. 4. Venous pH at post-exercise, HCO₃? at post-exercise and rest-30 min. in A group and pH at post-exercise and rest-10, 20 min., HCO₃? at post-exercise were showed significant changes. But there were not showed significant difference between two groups. 5. K?? level in B group was showed significant difference compared to A group. And also K?? level at rest-30 min. in B group was showed significant change. The results indicated that Chung-seo-ik-pi-tang had the effects of ergogenic aids on fatigue and recovery during 2,000 m maximal running.

고식적 검사로 간외 전이를 진단하지 못한 원발성 간암 환자에서 간이식 전에 시행한 전신 FDG-PET의 역할

이원우,류진숙,양유정,김재승,여정석,문대혁,이승규 대한핵의학회 2002 핵의학 분자영상 Vol.36 No.6

목적: 원발성 간암의 치료를 위해 간이식이 시행되고 있으나, 8-54%의 환자에서는 이식 후 원격 전이로 인한 재발이 보고 되고 있다. 이 연구는 간이식 예정인 원발성 간암 환자들에서 고식적인 검사로 진단하지 못한 간의 전이 진단에 있어서 FDG-PET의 유용성을 평가하고자 시행되었다. 대상 및 방법: 2001년 8월 이후 본원에서 간이식을 계획하고 전신 FDG-PET을 시행한 환자 중, FDG-PET 검사 이전에 복부 초음파와 CT, 흉부 x선 검사와 CT, 골스캔 등의 고식적인 검사를 시행하여 전이의 증거가 없거나(n=22), 애매한 이상 소견이 있었던(n=4) 원발성 간암 환자 26명(남:여=23:3), 평균 나이 55.7세)을 조사하였다. FDG-PET에서 양성을 보인 결과는 조직 검사나 임상적인 추적 검사로 전이 여부를 확인하였다. 결과: 고식적 검사에서 애매한 이상 소견이 있었던 환자 4명 중 3명의 6개 병변이 FDG-PET에서 국소 대사 항진을 보였고, 전이로 확인되어 간이식을 시행하지 않았다. 이 중 5 병변들은 의심되지 않았던 부위에서 새로 발견된 것이었다. 다른 1명은 PET에서 음성 소견으로 간이식을 시행하였다. 고식적인 검사에서 전이를 의심할 만한 소견이 없었던 22명 중에서는 5명의 환자에서 7개의 간의 국소 대사항진 병변들이 FDG-PET에서 발견되었는데, 이들 줄 1명은 2 개의 전이 병변이 확인되어 간이식을 시행하지 않았다. 다른 4명의 환자들에서 보인 5개의 국소 대사항진 병변들은 양성병변으로 확인되었고 이 중 3명은 간이식을 시행하였다. 요약하면, FDG-PET으로 4명의 환자에서 고식적인 검사로 찾지 못하던 전이 병변을 찾아 불필요한 간이식을 피할 수 있었다. 모두 17명에서 간이식이 시행되었다. 간의 조직 검사 소견과 비교하였을 때 생존 원발성 간암을 진단하는 FDG-PET의 민감도는 55.6% (5/9)이었고, 특이도는 87.5% (7/8)이었다. 결론: FDG-PET 전신 스캔은 간이식 예정인 원발성 간암 환자들에서 이전에 시행한 고식적인 검사들로 진단하지 못한 전이 병소들을 추가로 진단하여 불필요한 간이식 수술을 줄이는데 기여할 수 있었다. Purpose: Liver transplantation (LT), one of the therapeutic options of primary liver cancer has been suffering from recurrence caused by metastasis in 8-54% of patients. This study was performed to investigate whether FDG-PET is useful for detecting hidden metastasis in LT candidates. Materials and Methods: Twenty-six patients (male:female=23:3, mean age 55.7 year) underwent FDG-PET. Their previous conventional diagnostic studies (CDS) like a abdomen US and CT, chest x-ray and CT, and bone scan were negative (n=22) or equivocal (n=4) for metastasis. Positive FDG-PET findings were confirmed by biopsy or clinical follow-up. Results: Among 4 patients with equivocal metastatic lesions on CDS, 3 had 6 hypermetabolic lesions on FDG-PET, which were confirmed as metastasis and subsequently LTs were cancelled. Of these, 5 lesions were initially negative on CDS. Remained 1 patient underwent LT with a negative FDG-PET result. Among 22 patients without metastasis on CDS, 5 had 7 hypermetabolic lesions on FDG-PET. One of these patients proved to have 2 metastatic lesions, and LT was cancelled. The other 4patients had 5 hypermetabolic lesions on FDG-PET, which were confirmed as benign lesions, and 3 patients of them underwent LT. In summary, FDG-PET was useful in avoiding 4 unwarranted LT by detecting unsuspected metastatic lesions on CDS. A total of 17 patients underwent LT. In comparison with pathology, the sensitivity and specificity of FDG-PET for detecting viable primary liver cancer were 55.6% (5/9) and 87.5% (7/8), respectively. Conclusion: FDG-PET can detect additional hidden metastasis and contribute to reducing unwarranted LT in the patients with primary liver cancer. (Korean J Nucl Med 2002;36;368-80)

운전자 건강과 교통사고 예방에 관한 연구

李裕燦,高在坤 단국대학교 1995 論文集 Vol.29 No.-

The purpose of this research is to examine how driver's physical and psychological condition affects on traffic offence or accident and to find the reasons. 192 people was selected as sample by means of Intended Sampling method out of 220 traffic offenders who were participating in traffic education program after consulting with some specialist about offenders condition (health), a questionnaire composed of 40 questions was mode Then the data was analyzed by the SPSS PC program of SM-430 computer. Comprehensive examining the relationships between traffic offenders and their health, drivers who got traffic accidents and their health, and overspeeding drivers and their health deduced the following results. First, even though undesirable physical and psychological condition is a subject to high frequency of offence or accident, most of drivers used to ignore these factor. Second, driver's psychological condition affects overspeeding that lead big graffic accident. Temselves should recognize the importance of such factors but also many education institutes have to analyze the main reason. And educational programs about drivers physical and psychological condition ought to be designed in the long term view.