Sulfonyl Hydrazide-Based Polymeric Foaming Agent Nanoparticles

정재욱,김구성,이소림,김건우,김동현,정일두 한국고분자학회 2017 Macromolecular Research Vol.25 No.2

Polymeric foaming agent (PFA), poly(methacryloyl toluenesulfonylhydrazide) (poly(MATSH)), was synthesized from p-toluenesulfonyl hydrazide (TSH) with methacryloyl chloride (MAC) and transformed into nanoscale material by using a method of emulsion-solvent evaporation with polyvinyl alcohol (PVA) as an emulsifier. Average particle size of poly(MATSH) nanoparticle was determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM), in comparison with TSH and MATSH monomer nanoparticles. Thermal decomposition temperature of the prepared nanoparticles was measured by using thermogravimetric analysis (TGA). A fraction of PVA remained in poly(MATSH) nanoparticle in spite of repeated washing increased decomposition temperature of the nanoparticles. The exothermic temperature of poly(MATSH) nanoparticle was examined by using differential scanning calorimetry (DSC). Furthermore, the polymer incorporated with poly(MATSH) nanoparticle according to foaming formulation based on styrene butadiene rubber (SBR) by compression molding showed higher expansion ratio due to higher surface volume and also made finer and more uniform cell structure due to smaller particle size and better compatibility with polymer and other fillers than those of poly(MATSH) in the morphology study of scanning electron microscopy (SEM).

염산티트라싸이클린의 적용시간에 따른 다공성 임프란트 표면 미세구조의 변화

정재욱,허익,권영혁,박준봉,정종혁,Jeong, Jae-Wook,Herr, Yeek,Kwon, Young-Hyuk,Park, Joon-Bong,Chung, Jong-Hyuk 대한치주과학회 2006 Journal of Periodontal & Implant Science Vol.36 No.2

Mechanical and chemical methods are the two ways to treat the implant surfaces. By using mechanical method, it is difficult to eliminate bacteria and by-products from the rough implant surface and it can also cause the structural change to the implant surface. Therefore, chemical method is widely used in order to preserve and detoxicate the implant surface more effectively. The purpose of this study is to evaluate the effect of tetracylcline-hydrochloride(TC-HCI) on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, SLA surface and porous surface were used in this study. Implant surface was rubbed with sponge soaked in 50mg/ml TC-HCI solution for $\frac{1}{2}$ min., 1 min., $1\frac{1}{2}$ min., 2 min., and $2\frac{1}{2}$ min. respectively in the test group and with no treatment in the control group. Then, specimens were processed for scanning electron microscopic observation. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. In the SLA surfaces, the control specimen showed that the macro roughness was achieved by large-grit sandblasting. Subsequently, the acid-etching process created the micro roughness, which thus was superimposed on the macro roughness. Irrespective of the application time of 50mg/ml TC-HCI solution, in general, test specimens were similar to control. 3. In the porous surfaces, the control specimen showed spherical particles of titanium alloy and its surface have a few shallow ridges. The roughness of surfaces conditioned with tetracycline-HCI was lessened and seen crater-like irregular surfaces relative to the application time. In conclusion, pure titanium machined surfaces and SLA surfaces weren't changed irrespective of the application time of tetracycline-HCI solution. But the porous surfaces conditioned with tetracycline-HCI solution began to be slightly changed from 2 min. This results are expected to be applied to the regenerative procedures for peri-implantitis treatment.

Dexmedetomidine and remifentanil in the perioperative management of an adolescent undergoing resection of pheochromocytoma -A case report-

정재욱,박정규,전상윤,김용한,남소현,최영균,방시라 대한마취통증의학회 2012 Korean Journal of Anesthesiology Vol.63 No.6

A 15-year-old adolescent with unilateral multiple adrenal pheochromocytoma had an episode of subcortical intracerebral hemorrhage and seizure 6 weeks before the surgery. He was pretreated with terazosin, losartan, atenolol and levetiracetam for 2 weeks. Dexmedetomidine was started in the preoperative waiting area, and a combination of dexmedetomidine and remifentanil was continuously infused for most of anesthetic time. To control blood pressure, bolus injection of remifentanil and low-dose infusion of sodium nitroprusside, nicardipine, and esmolol were administered during three adrenergic crises. There was minimal post-resection hypotension, and his trachea was extubated safely 20 min after the surgery. He was discharged without noticeable complication. His catecholamine levels showed the steadily decreasing pattern during the operation in this case. Though a combination of dexmedetomidine and remifentanil may not prevent the hemodynamic instability impeccably during the tumor manipulation, this combination seems to be the way of interrupting release of catecholamines and minimizing hemodynamic fluctuations.

복강경 담낭 절제술에 있어서 표준 진료 지침의 유용성

정재욱,최정범,서미애,이수지,천자혜,김경식 대한내시경복강경외과학회 2016 Journal of Minimally Invasive Surgery Vol.19 No.2

Purpose: Under the rising demand of health services, the critical pathway (CP) which standardizes the practice guideline was introduced as a mean to provide quality healthcare service. CP may increase the patient’s satisfaction rate by providing with the systematic and consistent service. We aimed to evaluate the significance of CP by developing and applying CP to the patients undergoing laparoscopic cholecystectomy. Methods: From June 2010 to July 2011, 148 patients underwent elective laparoscopic cholecystectomy. Patients were divided into two groups including 57 patients in CP group and 91 patients in non-CP group. Retrospective review of related hospital costs were analyzed and compared for both groups. Survey results on satisfaction for CP group were also analyzed. Results: The mean age for CP group was 22.7 years and 37.9 years for non-CP group. Number of hospitalized days were one day for CP group and 2.51 days for Non-CP group with p<0.001. All variables in cost analysis showed significant reduction in CP group compared to Non-CP group. The satisfaction rate in CP group scored 8 points out of 10. Conclusion: Results have shown benefit of the CP group from the financial point of the view. Current inclusion criteria for CP are very limited and still in development for a solid protocol. Further efforts with a large-scale comparative study to broaden the indication for CP are desired.

동적 신경망에 기초한 불확실한 로봇 시스템의 적응 최적 학습제어기

정재욱,국태용,이택종 대한전자공학회 1997 전자공학회논문지SC (System and control) Vol.s34 No.6

This paper presents an adaptive optimal learning controller for uncertian robot systems which makes use fo simple DNN(dynamic neural network) units to estimate uncertain parameters and learn the unknown desired optimal input. With the aid of a lyapunov function, it is shown that all that error signals in the system are bounded and the robot trajectory converges to the desired one globally exponentially. The effectiveness of the proposed controller is hsown by applying the controller to a 2-DOF robot manipulator.

Patients' Assessment of Community Primary and Non-primary Care Physicians in Seoul City of South Korea

정재욱,성낙진,박기흠,김선웅,이재호 대한가정의학회 2011 Korean Journal of Family Medicine Vol.32 No.4

Background: It is important to know the current level of primary care performance in order to evaluate and plan for desirable health policy. We tried to compare patient's assessment of primary (family physician, general practitioner,internist, pediatrician, and general surgeon) and non-primary (the other specialties) care physicians. Methods: Study subjects were physicians of primary care clinics in Seoul. The study subject evaluators were Seoul citizens who were selected by a list-assisted random digit dialing sampling method and who had visited their primary care clinic on six or more occasions over a period of more than 6 months as a usual source of care. The modified version of the Korean Primary Care Assessment Tool was used for the evaluation of primary care performance. The data were collected with the aid of a computer-assisted telephone interview system from June 29 to July 22, 2009. Results: The data on 260 individuals were used for analysis. The mean scores of primary and non-primary care physician group were respectively 1.19 and 0.85 in the comprehensiveness domain, 1.00 and 0.83 in the coordination domain,1.54 and 1.31 in the family/community orientation, and 1.24 and 0.99 as an average of 3 domains above. The scores in the comprehensiveness domain and the average of 3 domains were significantly higher in the primary than in the nonprimary care physician group. Conclusion: Primary care physicians showed superior performance compared to non-primary care physicians in comprehensiveness domain and in the average of comprehensiveness, coordination, and family/community orientation domains.

Sensitivity analysis for a system of generalized nonlinear mixed quasi-variational inclusions with (A,η)-accretive mappings in Banach spaces

정재욱,김수환 대한수학회 2009 대한수학회보 Vol.46 No.6

In this paper, we study the behavior and sensitivity analysis of the solution set for a new system of parametric generalized nonlinear mixed quasi-variational inclusions with (A,η)-accretive mappings in q-uniformly smooth Banach spaces. The present results improve and extend many known results in the literature. In this paper, we study the behavior and sensitivity analysis of the solution set for a new system of parametric generalized nonlinear mixed quasi-variational inclusions with (A,η)-accretive mappings in q-uniformly smooth Banach spaces. The present results improve and extend many known results in the literature.

An iterative method for nonlinear mixed implicit variatinnal inequalities

정재욱 호남수학회 2004 호남수학학술지 Vol.26 No.4

In this paper, we develop an iterative algorithm for solving a class of nonlinear mixed implicit variational inequalities in Hilbert spaces. The resolvent operator technique is used to establish the equivalence between variational inequalities and fixed point problems. This equivalence is used to study the existence of a solution of nonlinear mixed implicit variational inequalities and to suggest an iterative algorithm for solving variational inequalities. In our results, we do not assume that the mapping is strongly monotone.

소유경영기업과 전문경영기업의 스톡옵션 부여 후 장기성과 결정요인

정재욱,배길수 한국재무관리학회 2007 재무관리연구 Vol.24 No.1

This study examines the determinants of the long-run stock price performance of the firms that granted stock options between 1997 and 2002. We divide the sample into the firms run by the owner and those run by the professional manager. If the primary reason for granting stock options is reduction of the agency costs between the manager and shareholders, the effect of stock options is likely to be more pronounced in the firms run by the professional manager. We find that the long-run abnormal returns of the firms run by the professional manager are negatively associated with the shareholdings by the manager and the book-to- market value and are positively associated with the earnings growth and the size of the outstanding stock options. In contrast, the long-run abnormal returns of the firms run by the owner are negatively associated with the cash flows rate and the sales growth rate and are positively associated with the firm size. This is consistent with the argument that the agency costs arising from the conflicts between the manager and shareholders are an important determinant of the post-stock option granting long-run stock price performance only in the firms run by the professional manager. The results also suggest that stock options in the firms run by the owner are likely to be used for the purposes such as additional compensation, a signaling device, a means that reduce the agency costs within firms. 본 연구는 한국유가증권시장(거래소시장)에 상장된 기업 중 1997년부터 2002년까지 스톡옵션을 부여한 기업을 소유경영기업과 전문경영기업으로 분류하여 스톡옵션 도입 후 장기성과에 영향을 주는 요인을 분석한다. 스톡옵션 제도의 도입목적이 주주와 경영자 사이의 대리인비용 절감이라면, 소유경영기업보다는 전문경영기업이 스톡옵션 도입 후 장기성과를 분석하는데 적합할 것이다. 선행연구에서는 주주와 경영자 사이의 대리인비용은 경영자지분과 시가장부가비율이 낮을수록, 현금흐름률, 매출성장률이 높을수록 높다고 주장하였다. 본 연구는 다양한 대리인비용의 대용치를 사용하여 스톡옵션 부여 후 장기주가성과를 분석하였다.연구결과 전문경영기업의 장기주가성과는 경영자지분 및 시가장부가비율과는 음의관계를, 매출성장률, 일인당 옵션규모와는 양의 관계를 갖는다. 반면에 소유경영기업의 장기주가성과는 현금흐름률 및 매출성장률과는 음의관계를, 자산규모와는 양의관계를 갖는다. 이러한 결과는 전문경영기업에서는 주주와 경영자 사이의 대리인비용이 스톡옵션 도입 후 성과를 결정하는 중요한 요소임을 의미한다. 그러나 소유경영기업에서는 스톡옵션이 주주와 경영자 사이의 대리인비용 절감 보다는 비현금보상, 신호, 기업 내 대리인비용 절감 등의 목적으로 이용된다는 가능성을 제시한다. 본 연구는 기업특성과 목적에 부합하도록 스톡옵션을 활용하는 것이 기업 성과 향상에 기여한다는 해석과 일관성이 있다.

住商複合 建築의 設計事項에 관한 硏究 : 一單一高層形 住商複合을 中心으로 Focused on the Single Tower Type Mixed-Use Building

鄭在旭 단국대학교 1995 論文集 Vol.29 No.-

The purpose of this study is to evaluate fundamental factors of designing mixed-use building in accordance with building purpose and functional characteristics, thus to propose for a feasible design strategics. The study conducts real design problems with the project site located in 76-1 Hwajung region of Koyang Kyungki to seek for a multiplicity of design problems and issues of the mixed-use building in process of the development. By the investigation of relative design composition factors, the study reinforces importance of creating a better and practical mixed-use environment with a much depend on the level of comprehensive design solutions. The design problem is mainly focused on the single tower type of mixed-use building due to the located site conditions as well as given space program of the complex.