Rare Cause of Hydronephrosis

유달산,홍준혁 대한비뇨의학회 2013 Investigative and Clinical Urology Vol.54 No.3

음경골절의 수술적 치료 시 장기합병증 발생의 위험요소

유달산,홍범식,박종연,안태영 대한남성과학회 2004 The World Journal of Men's Health Vol.22 No.1

Ru/Al₂O₃/메탈폼 촉매를 이용한 친환경 액체추진제 분해

유달산,전종기,Yoo, Dalsan,Jeon, Jong-Ki 한국청정기술학회 2019 청정기술 Vol.25 No.3

Hydroxylammonium nitrate (HAN) 기반 액상 추진제는 발암물질이 아니며 연소가스 또한 독성이 거의 없어서 환경 친화적인 추진제로 주목을 받고 있다. 추력기에서 HAN 기반 액체추진제를 분해하는데 사용되는 촉매는 저온 활성 및 고내열성을 동시에 보유하고 있어야 한다. 본 연구의 목적은 metal foam 표면에 alumina slurry를 wash coating 방법으로 담지한 후, 루테늄(ruthenium) 전구체를 그 위에 담지하여 Ru/alumina/metal foam 촉매를 제조하고, 이 촉매의 HAN 수용액 분해 활성을 평가하는 것이다. Wash coating 방법으로 metal foam 지지체에 알루미나를 담지시키는 과정에서 wash coating 반복 횟수가 alumina/metal foam의 물리적 특성에 미치는 영향을 분석하였다. 알루미나 wash coating 횟수가 증가할수록 약 7 nm의 직경을 갖는 메조기공이 지속적으로 발달하여 표면적과 기공 부피가 증가하는데, metal foam에 알루미나를 코팅하는 과정을 12 회 반복하는 것이 최적이라고 판단하였다. 이 지지체에 Ru을 담지한 Ru/alumina/metal foam 촉매의 표면에도 메조기공이 잘 발달하였다. 활성금속과 알루미나를 담지하지 않은 metal foam 자체만으로도 HAN 수용액의 분해반응을 촉진할 수 있음을 알 수 있었다. Ru/alumina/metal foam-550촉매의 경우는 열분해 반응에 비해서 분해개시온도를 큰 폭으로 낮추었고, ${\Delta}P$를 크게 증가시킬 수 있어서, HAN 수용액 분해 반응에서 우수한 활성을 보였다. 그러나 이 촉매를 $1,200^{\circ}C$에서 소성하면 반응 활성이 저하되는데 이는 촉매의 표면적과 기공 부피가 급격하게 감소하고 Ru이 소결되기 때문이다. 추가적인 연구를 통해서 Ru/alumina/metal foam의 내열성을 개선할 필요성이 있다. Hydroxylammonium nitrate (HAN)-based liquid propellants are attracting attention as environmentally friendly propellants because they are not carcinogens and the combustion gases have little toxicity. The catalyst used to decompose the HAN-based liquid propellant in a thruster must have both low temperature activity and high heat resistance. The objective of this study is to prepare an Ru/alumina/metal foam catalyst by supporting alumina slurry on the surface of NiCrAl metal foam using a washing coating method and then to support a ruthenium precursor thereon. The decomposition activity of a HAN aqueous solution of the Ru/alumina/metal foam catalyst was evaluated. The effect of the number of repetitive coatings of alumina slurry on the physical properties of the alumina/metal foam was analyzed. As the number of alumina wash coatings increased, mesopores with a diameter of about 7 nm were well-developed, thereby increasing the surface area and pore volume. It was optimal to repeat the wash coating alumina on the metal foam 12 times to maximize the surface area and pore volume of the alumina/metal foam. Mesopores were also well developed on the surface of the Ru/alumina/metal foam catalyst. It was found that the metal form itself without the active metal and alumina can promote the decomposition reaction of the HAN aqueous solution. In the case of the Ru/alumina/metal foam-550 catalyst, the decomposition onset temperature was significantly lowered compared with that of the thermal decomposition reaction, and ${\Delta}P$ could be greatly increased in the decomposition of the HAN aqueous solution. However, when the catalyst was calcined at $1,200^{\circ}C$, the catalytic activity was lowered inevitably because the surface area and pore volume of the catalyst were drastically reduced and Ru was sintered. Further research is needed to improve the heat resistance of Ru/alumina/metal foam catalysts.

2P-641 Pt/Al₂O₃ bead 촉매를 이용한 hydroxyl ammonium nitrate(HAN) 기반 liquid monopropellant 분해 연구

유달산,허수정,김문정,우재규,조영민,전종기 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

일반적으로 인공위성 추력기에 사용되는 hydrazine(N₂H₄) 단일추진제는 강력한 독성으로 인한 취급 안전성 문제로 친환경 저독성 액상추진제 연구가 진행중이며 그 중 HAN은 발암, 돌연변이 유발물질이 없는 환경친화적인 특성 뿐 아니라 비추력 또한 우수하기 때문에 관심이 집중되고 있다. 그러나 HAN 기반 액상 단일 추진제에는 최종연소온도를 낮추기 위해 H₂O를 용해시키기 때문에 수분함량이 많아 점화가 어려운 단점이 있다. 따라서 HAN 기반 액상 단일추진제는 촉매를 이용하여 촉매분해를 해야 한다. 본 연구에서는 함침법을 통해 Pt/Al₂O₃ bead 촉매를 제조하였다. HAN 기반 액상 단일추진제 분해반응 실험은 자체 제작한 batch reactor를 이용하여 분해개시온도 와 압력의 변화를 확인하였다. 제조한 촉매의 물리화학적 특성을 BET, XRD, XRF를 이용하여 분석하였다.

소아에서 복강경 신장 수술의 학습 곡선 분석

유달산,방정균,김건석 대한비뇨의학회 2009 Investigative and Clinical Urology Vol.50 No.4

Purpose: To guide pediatric urologists to start laparoscopic renal surgery in children, we analyze our experience with various laparoscopic renal surgeries to highlight the surgical outcomes and the degree of completion of specific laparoscopic skills. Materials and Methods: We retrospectively analyzed 51 children who underwent laparoscopic renal surgery by a single surgeon between March 2002 and July 2008 (25 nephrectomies, 12 nephroureterectomies, 10 heminephrectomies, 3 heminephroureterectomies, and 1 heminephrectomy in a horseshoe kidney). We compared the degree of completion of specific laparoscopic skills as well as operative parameters such as operative time, estimated blood loss, and complication rate. Results: All laparoscopic renal surgeries were completed as planned without open conversions. In the nephrectomy group (nephrectomy+nephroureterectomy), the mean operative time decreased after 10 cases (239 minutes vs. 145 minutes, p<0.001). A decrease in mean estimated blood loss was also noted after 10 cases (119 vs. 32 ml, p<0.05). The complication rate decreased after 20 cases (30% vs. 4%, p<0.05). In all patients, the completion rates for specific laparoscopic skills were 98% for trocar insertion, 80% for removal of a pathological lesion, 82% for retroperitoneal insufflation, and 73% for refluxing ureterectomy and suturing. The overall completion rate increased after 18 cases (79% vs. 91%, p<0.05). Conclusions: Operative time and blood loss in pediatric laparoscopic renal surgery are rapidly improved with experience. Improvement in the complication rate and specific laparoscopic skills require more time. We recommend that pediatric urologists beginning laparoscopic surgery try complex surgeries such as heminephrectomy or heminephroureterectomy after they have surmounted the learning curve of easy surgeries such as nephrectomy or nephroureterectomy. Purpose: To guide pediatric urologists to start laparoscopic renal surgery in children, we analyze our experience with various laparoscopic renal surgeries to highlight the surgical outcomes and the degree of completion of specific laparoscopic skills. Materials and Methods: We retrospectively analyzed 51 children who underwent laparoscopic renal surgery by a single surgeon between March 2002 and July 2008 (25 nephrectomies, 12 nephroureterectomies, 10 heminephrectomies, 3 heminephroureterectomies, and 1 heminephrectomy in a horseshoe kidney). We compared the degree of completion of specific laparoscopic skills as well as operative parameters such as operative time, estimated blood loss, and complication rate. Results: All laparoscopic renal surgeries were completed as planned without open conversions. In the nephrectomy group (nephrectomy+nephroureterectomy), the mean operative time decreased after 10 cases (239 minutes vs. 145 minutes, p<0.001). A decrease in mean estimated blood loss was also noted after 10 cases (119 vs. 32 ml, p<0.05). The complication rate decreased after 20 cases (30% vs. 4%, p<0.05). In all patients, the completion rates for specific laparoscopic skills were 98% for trocar insertion, 80% for removal of a pathological lesion, 82% for retroperitoneal insufflation, and 73% for refluxing ureterectomy and suturing. The overall completion rate increased after 18 cases (79% vs. 91%, p<0.05). Conclusions: Operative time and blood loss in pediatric laparoscopic renal surgery are rapidly improved with experience. Improvement in the complication rate and specific laparoscopic skills require more time. We recommend that pediatric urologists beginning laparoscopic surgery try complex surgeries such as heminephrectomy or heminephroureterectomy after they have surmounted the learning curve of easy surgeries such as nephrectomy or nephroureterectomy.

경사각이 변하는 열차폐판을 가진 전자장비내의 자연대류현상 ( Natural Convection Phenomena in Electronic Equipment with Heat Baffles )

유달산,이병우,서상호,유상신 대한기계학회 1996 대한기계학회 춘추학술대회 Vol.- No.-

신배게실결석의 내비뇨기과적 치료 결과

유달산,박태한,박형근 대한비뇨의학회 2005 Investigative and Clinical Urology Vol.46 No.2

Purpose: A symptomatic renal calyceal diverticular stone is a rare occurrence. Endourologic techniques, including laparoscopy, retrograde ureterorenoscopy(URS) and percutaneous nephrolithotomy(PNL) have been used for the treatment of this disease. Herein, we reviewed our experiences of treating stones in calyceal diverticulum with URS or PNL. Materials and Methods: We retrospectively reviewed 23 patients who underwent PNL(12 cases) or URS(11 cases) for the treatment of symptomatic calyceal diverticular stones. A direct target puncture of the diverticulum was made in the PNL group and a flexible or semi-rigid ureteroscope was used to reach the diverticulum in the URS group. The diverticular neck was either incised with Holmium:YAG laser or dilated. Extracorporeal shockwave lithotripsy(ESWL) was performed prior to the procedure in 9 of the 23 cases(2 in the PNL group and 7 in the URS group). Results: A complete stone-free state, with symptomatic resolution, was obtained in 11 of the 12 in the PNL group and in 7 of the 11 in the URS group. Success in the PNL group depended on an accurate puncture into the diverticulum and successful placement of the nephrostomy catheter into the renal pelvis through the diverticular neck. Success with the URS was achieved when the ureteroscope passed into the diverticulum and the double-J stent had been optimally placed. Seven of the 9 cases with prior ESWL achieved a stone-free state, while all the prior ESWL cases with successful access achieved a stone-free state. Conclusions: A calyceal diverticular stone can be treated with PNL or URS in most cases, although they are technically challenging procedures. In both procedures, access into the diverticulum is the most important step for a successful outcome. If access can be gained, preoperative ESWL could facilitate clearance of the stone and reduce the operating time, as there is no need for intraoperative lithotripsy.

소아 환자에서 복강경을 이용한 신장 수술 시 접근방법의 선택

유달산,김건석 대한비뇨의학회 2007 Investigative and Clinical Urology Vol.48 No.3

Ru이 담지된 Honeycomb 촉매를 이용한 친환경 단일액상추진제 분해 연구

유달산,우재규,한승호,박연수,조영민,전종기 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

최근 우주선 궤도 및 자세 제어에 사용되는 추진제는 취급 안전성(저독성)과 비용절감이 요구되고 있다. 가장 대표적인 추진제인 hydrazine은 강력한 독성이 있기 때문에 친환경 저독성 액상추진제에 관한 연구가 활발하게 진행 중이다. hydrazine을 대체하기 위한 친환경 추진제인 hydroxylammonium nitrate(HAN)은 우수한 비추력을 가지며 고밀도, 발암 및 돌연변이 유발물질이 없다는 장점으로 인해서 많은 관심을 받고 있다. 그러나 수용액 상태에서의 점화를 위해서는 촉매분해가 필요하다. 본 연구에서는 코디어라이트 지지체에 과량용액 함침법을 통해 Ru을 담지 하여 촉매를 제조하였다. Ru의 담지량을 변화시켜 제조한 촉매의 특성을 BET, XRD, XRF를 이용하여 분석하였다. Ru/honeycomb 촉매를 사용한 HAN의 분해 반응에서 분해개시 온도와 압력의 변화를 측정하였다.

Cu/honeycomb 및 Pt-Cu/honeycomb 촉매를 이용한 이온성 액체추진제 반복 분해 연구

유달산,우재규,한승호,오설영,조영민,전종기 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

항공우주산업에서 핵심 기술 중 하나인 이온성 액체추진제는 일반적으로 hydrazine(N₂H₄)을 사용한다. 하지만 분해 시 발생되는 할로겐 화합물 그리고 돌연변이 유발물질 등 강력한 독성을 가지고 있기 때문에 이를 대체하기 위한 연구가 진행중이다. Hydroxylammonium nitrate(HAN), ammonium dinitramide(ADN)은 hydrazine을 대체하기 위한 대표적인 친환경 저독성 액체추진제이다. 특히 HAN은 높은 안정성, 성능 그리고 훌륭한 비추력을 가지고 있다. 하지만 점화를 위한 온도가 매우 높으며, 연소 시 높은 flame temperature의 발생 때문에 고활성 및 고내열성의 촉매를 사용해야 한다, 본 연구에서는 cordierite (Si-MgO-Al)로 이루어진 honeycomb지지에 wet impregnation으로 Cu금속을 코팅 또는 Pt금속과 Cu금속을 코팅하여 촉매를 제조하였다. BET 그리고 XRD, XRF를 통해 촉매 특성을 분석하였고, 자체 제작한 batch reactor에서 분해 특성을 연구하였다.