연소합성을 이용한 저온형 고체산화물 연료전지용 나노구조 세리아계 전해질 제조

조승환,김종호,김도경,Jo, Seung-Hwan,Kim, Jong-Ho,Kim, Do-Kyung 한국세라믹학회 2005 한국세라믹학회지 Vol.42 No.12

Gadolinia-doped ceria nanopowder was prepared by glycine-nitrate combustion method with different glycine/nitrate mixing ratio. The characteristics of the synthesized powder were investigated by X-ray diffraction method, transmission electron microscopy, thermal gravity, differential thermal analysis and thermo-mechanical analysis. The smallest powder was obtained with glycine/nitrate ratio 1.00 and the lowest organic and water vapor contained powder was made with glycine/nitrate ratio 1.75. According to dilatometry, fast densification was occurred around $1000^{\circ}C$ and shows full density over $1300^{\circ}C$. Finally near-fully dense ceria electrolyte was fabricated with conventional sintering technique. Glycine-nitrate process yields fine nanopowders which enable low temperature sintering and fabrication of fully dense and nanostructured oxide electrolyte.

Gadolinium-doped Ceria/Magnesia (CGO/MgO) 복합체 전해질의 전기적 특성 분석

조승환,김도경,Jo, Seung-Hwan,Muralidharan, P.,Kim, Do-Kyung 한국재료학회 2008 한국재료학회지 Vol.18 No.9

Composites of gadolinium-doped ceria/magnesia(CGO/MgO) were synthesized and characterized for the electrolytes of intermediate temperature solid oxide fuel cells. XRD and SEM results revealed that composite electrolytes consisted of their own phases after sintering at $1400^{\circ}C$ without noticeable solid solution of Mg into CGO. As the MgO content increased, the total electrical conductivity decreased, which might be attributed to the decrease of grain boundary conductivity, possibly due to the lowering of the continuity of the CGO grains and blocking effects of the insulating MgO phase. The space charge effect may not be a significant factor to affect the electrical conductivity of the CGO/MgO composites.

자바 카드상에서의 3GPP, 3GPP2 인증 메커니즘 구현

조승환(Seung-hwan Jo),전성익(Sung-ik Jun),이정우(Jeong-woo Lee),이옥연(Ok-yeon Yi),한진희(Jin-hee Han),이세광(Se-kwang Lee) 한국정보보호학회 2003 정보보호학회논문지 Vol.13 No.6

대면적 SOFC 단전지 개발 현황

조승환(Jo, Seung Hwan),박상현(Park, Sang-Hyun),이상철(Lee, Sang-Cheol),정기석(Chung, Ki Suk),황정태(Hwang, Jung-Tae) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06

SOFC 발전 시스템은 친환경 고효율 에너지 발전 미래 에너지기술로서 개발의 초점이 되고 있다. SOFC는 연료전지 발전 기술 중 최고효율과 최장 수명을 가지며 유일하게 기존 발전기술과 가격 경쟁이 가능한 것으로 알려지고 있다. 현재 분산 발전용으로 개발이 진행되고 있으며 향후 중앙발전, 휴대용, 가정용 및 수송용 등으로 그 시장이 확대될 것으로 예상된다. 분산 발전 SOFC 개발을 위해서는 시스템 Scale-up이 기술 확보가 관건이며 특히 스택 제조 비용의 2/3 이상을 차지하는 대면적 단전지 제조 공정 기술 개발이 필요하다. 단전지 대면적화는 원가 절감 및 성능 개선을 기대할 수 있게 하므로 분산 발전 SOFC 상용화를 위한 핵심 기술이라 할 수 있다. 그러나 기존의 국내 SOFC 연구는 시스템이나 소형 단전지 위주로 진행되어 왔으며 대면적 단전지 제조를 위한 핵심 공정 기술에 대한 연구는 취약한 상황이다. 또한 랩스케일의 소규모 연구를 뛰어넘는 양산 기술 개발에 대한 연구는 전무한 실정이다. 또한 재료 및 공정 적합성을 요구하는 대면적 SOFC 단전지의 양산 기술 개발을 위해서는 원료 분말 및 기초소재의 국산화를 통한 제조 공정 윈도우를 확대하여 제조 수율을 향상하는 것이 매우 중요하다. 본 논문에서는 그동안 포스코파워(주)에서 대면적 SOFC 단전지 양산 기술 개발을 위해 추진 중인 400cm²급 대면적 SOFC 단전지의 제조 및 성능에 대한 연구 결과를 발표하고자 한다. 또한 대형 단전지 제조 공정의 재현성, 상용화 수준의 성능, 내구성 및 경제성 확보를 위한 공정 개선을 위한 포스코파워(주)의 연구 현황 및 양산 기술 확보를 위한 제조 윈도우 확보 전략에 대해 발표하고자 한다.

연료전지용 LSGM 페로브스카이트계 전해질의 합성 및 특성 연구

성영훈,조승환,김도경,Seong, Young-Hoon,Jo, Seung-Hwan,Muralidharan, P.,Kim, Do-Kyung 한국세라믹학회 2007 한국세라믹학회지 Vol.44 No.12

The family of (Sr,Mg)-doped $LaGaO_3$ compounds, which exhibit high ionic conductivity at $600-800^{\circ}C$ over a wide range of oxygen partial pressure, appears to be promising as the electrolyte for intermediate temperature solid oxide fuel cells. Conventional synthesis routes of (Sr,Mg)-doped $LaGaO_3$ compounds based on solid state reaction have some problems such as the formation of impurity phases, long sintering time and Ga loss during high temperature sintering. Phase stability problem especially, the formation of additional phases at the grain boundary is detrimental to the electrical properties of the electrolyte. From this point of view, we focused to synthesize single phase (Sr,Mg)-doped $LaGaO_3$ electrolyte at the stage of powder synthesis and to apply relatively low heat-treatment temperature using novel synthesis route based on combustion method. The synthesized powder and sintered bulk electrolytes were characterized by XRD, TG-DTA, FT-IR and SEM. AC impedance spectroscopy was used to characterize the electrical transport properties of the electrolyte with the consideration of the contribution of the bulk lattice and grain boundary to the total conductivity. Finally, relationship between synthesis condition and electrical properties of the (Sr, Mg)-doped $LaGaO_3$ electrolytes was discussed with the consideration of phase analysis results.

회전근개파열에 대한 관절경하 봉합술후 자가골수혈장 주입법의 유용성

노경환 ( Kyung Hwan Noh ),조승환 ( Seung Hwan Jo ),문영래 ( Young Lae Moon ),유재원 ( Jae Won You ),송창훈 ( Chang Hoon Song ) 한국조직공학·재생의학회 2009 조직공학과 재생의학 Vol.6 No.1

To evaluate the efficacy of autologous bone marrow plasma injection after rotator cuff repair. Fifty six patients who were diagnosed with rotator cuff tear and had arthroscopic rotator cuff repair were selected. Twenty six patients had additional autologous iliac bone marrow plasma injection following arthroscopic rotator cuff repair and remaining 28 patients had repair procedure only. Aspirated iliac bone marrow was centrifuged at 1,800 rpm for 20 to 30 minutes before injection. Pain and function were evaluated using Constant Shoulder Score, University of California at Los Angeles Shoulder Scale, Oxford Shoulder Score and Visual Analogue Scale. Postoperative sonography was done to evaluate the condition of rotator cuff tendon. The group with autologous bone marrow plasma injection showed significantly better functional results. In songraphic examination, all rotator cuffs were healed successfully. Injection of autologous bone marrow plasma after rotator cuff repair may enhance biologic healing and thereby contribute to pain relief and functional improvement.

눈꺼풀 악성종양 수술에서 눈꺼풀 전층절제 후 시행한 직접봉합법의 미용적 효과

이동은(Dong Eun Lee),조승환(Seung Hwan Jo),함동식(Dong Sik Ham),이정재(Jung Jae Lee),양재욱(Jae Wook Yang) 대한안과학회 2018 대한안과학회지 Vol.59 No.2

Purpose: To evaluate the degree of eyelid deformation and satisfaction after direct closure in patients with 40-70% eyelid defects after resection of an eyelid malignant tumor. Methods: We retrospectively reviewed the clinical records of patients diagnosed with eyelid malignant tumors between January 2009 and June 2016, who were treated with resection of 40-70% of the eyelid, followed by reconstructed direct closure only or by direct closure with lateral canthotomy and cantholysis. Age, sex, diagnosis, tumor location, satisfaction, and complications were analyzed, and the ratio of horizontal width ratio and vertical height ratio were compared before and after surgery. Results: The results of satisfaction were: 12 patients (60%), very good; five patients (25%), good; and three patients (15%), fair. The average preoperative horizontal width ratio and vertical height ratio were 1.03 ± 0.01 and 1.08 ± 0.30, respectively. The average postoperative horizontal width ratio and vertical height ratio were 1.04 ± 0.08 and 1.01 ± 0.17, respectively There was no significant difference in horizontal width ratio or vertical height ratio before and after surgery (p = 0.314 and p = 0.087, respectively). Conclusions: Eyelid reconstruction with a direct closure can be performed without a flap or graft for 40-70% of eyelid defects when resecting the eyelid of a malignant eyelid tumor.

안와 주위에 발생한 유아 모세혈관종의 프로프라놀롤을 사용한 치료

이정후(Jung Hoo Lee),조승환(Seung Hwan Jo),양재욱(Jae Wook Yang) 대한안과학회 2018 대한안과학회지 Vol.59 No.5

Purpose: To report the clinical results of systemic propranolol for infantile periorbital hemangiomas. Methods: A retrospective analysis was performed on 11 patients who were treated with beta-blockers for cosmetic purposes or for those with an invalid visual axis from January 2010 to June 2017. A beta receptor blocker (propranolol) was administered at a dose of 2 mg/kg/day. The size of the lesion was analyzed using Image J software, version 1.47 (National Institutes of Health, Bethesda, MD, USA) at 1–2 months until the drug was discontinued after the initial treatment and discharge. We observed the occurrence of side effects such as hypoglycemia, nausea, and vomiting due to drug use. Results: Of the 11 patients, 9 (82%) were female and 2 (18%) were male. The location of the capillary hemangioma was in the upper eyelid of eight eyes (72.7%) and in the lower eyelid of three eyes (27.3%). The mean duration of treatment was 6.2 months and the mean follow-up period was 8.3 months. In 11 patients (100%), the lesion size was reduced. A temporary allergic response was seen in one patient, but no adverse side effects were seen that involved life-threatening effects. Conclusions: Infantile hemangiomas may cause cosmetic problems and amblyopia when invading the visual axis, which may require active treatment. Oral beta-blocker therapy for infantile hemangiomas of the orbit was safe for months or longer, with adequate treatment and with little to no adverse effects. J Korean Ophthalmol Soc 2018;59(5):397-402

레이저각막절삭성형술을 시행받은 환자에서 섬유주절제술 후 발생한 미만층판각막염

최지형(Ji Hyoung Chey),조승환(Seung Hwan Jo),이창규(Chang Kyu Lee) 대한안과학회 2017 대한안과학회지 Vol.58 No.1

목적: 레이저각막절삭성형술을 시행 받고 오랜 시간이 지난 환자에서 섬유주절제술 후 발생한 미만성 층판각막염 1예를 보고하고자한다. 증례요약: 12년 전 양안 레이저각막절삭성형술을 시행 받은 54세 남자가 양안 원발 개방각녹내장을 진단 받고 약물치료를 받았으나 안압이 조절되지 않고, 시야결손이 진행되는 양상을 보여 좌안 섬유주절제술을 시행 받았다. 기존에 진행하지 않는 좌안 각막의 옅은 상피밑 혼탁이 있었으나 특별한 치료는 받지 않았다. 술 후 1일째 좌안 결막 단춧구멍이 관찰되었고 누출이 지속되어 술 후 4일째국소 스테로이드제 점안을 중지하였다. 술 후 7일째 안압 상승 없이 각막 중심 부근의 미만성 층판각막염이 발생하였으며 추가로시행한 전안부빛간섭단층촬영상 각막 절편 아래 미만성 상피밑침윤 소견이 보였다. 국소 스테로이드제를 3시간 간격으로 2일 동안점안하였으나 각막염이 호전되지 않아 1시간 간격으로 증량하여 점안하였고, 술 후 9일째부터 각막염이 호전되었다. 수술 2개월 후, 상피밑 층판 침윤의 호전을 보였으나 완전한 관해는 보이지 않았다. 결론: 레이저각막절삭성형술을 시행 받은 안에서 섬유주절제술 후 적절한 국소 스테로이드제 점안이 이루어지지 않으면 미만성 층판각막염이 발생할 수 있으므로 주의를 요한다. Purpose: In the present study, a case of diffuse lamellar keratitis after trabeculectomy in a patient who had received laser in situ keratomileusis many years prior is reported. Case summary: A 54-year-old male diagnosed with binocular primary open-angle glaucoma underwent trabeculectomy in the left eye because of poor intraocular pressure control and visual field defect progression even with maximal medical treatments. Faint, non-progressing subepithelial opacities pre-existed in the left cornea but no treatment was administered. The patient had a history of laser in situ keratomileusis in both eyes 12 years prior. On the first postoperative day, conjunctival buttonhole was found and because leaking from the hole continued, topical steroid was discontinued on the fourth postoperative day. On the seventh postoperative day, diffuse lamellar keratitis developed on the central cornea without intraocular pressure elevation, and diffuse infiltration under the corneal flap was observed in the anterior segment on optical coherence tomography. The patient was treated with topical steroid eye drops every 3 hours for the first 2 days and the frequency was increased to every hour because the keratitis did not improve. On the ninth postoperative day, keratitis began to improve and 2 months postoperatively, subepithelial lamellar infiltration improved significantly but did not show complete remission. Conclusions: Diffuse lamellar keratitis can develop in an eye with laser in situ keratomileusis after trabeculectomy if appropriate treatment with topical steroid eye drops is not administered.

UMTS와 GSM 사이의 AKA와 핸드오버 분석

이세광(Se-Kwang Lee),조승환(Seung-Hwan Jo),이옥연(Ok-Yeon Yi),서창호(Chang-Ho Seo) 한국정보보호학회 2003 정보보호학회논문지 Vol.13 No.4