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조기헌,서윤수,권재환,김주연 대한이비인후과학회 2021 대한이비인후과학회지 두경부외과학 Vol.64 No.7
Perioperative stroke is one of the most fatal complications for patients as well as for doctors. Itis defined as a brain infarction or hemorrhage, occurring during or within 30 days after a surgicalprocedure. Most of the perioperative strokes have ischemic etiology while only 1% hashemorrhagic etiology, according to one study. The incidence of perioperative stroke is influencedby the complexity and type of the surgery. Generally, its incidence is very low, beingabout to 0.1-1.9%, with majority of the cases pertaining to cardiac, vascular, neurological surgeries. Based on our research, most cases are perioperative strokes that occur after cardiacand vascular surgeries. Here we report two cases of cerebral infarction after endoscopic sinussurgery, which are very rare.
Market Valuation of Technology Firms in KOSDAQ
조기헌,설성수 아시아기술혁신학회 2014 Asian Journal of Innovation and Policy Vol.3 No.2
This study aims to analyze the valuation of technology firms in the stock market to answer how before-market entities should be valuated. This study analyzes 230 market reports of 2012 for technology firms in the KOSDAQ under several hypotheses. The results are as follows: 90% used the 3 multiples methods consisting of PER multiples with 80%, PBR multiples 8.7% and EBITDA multiples 1.7%. The average of PER multiples was 15 with the range of 6.9 to 83. That of PBR multiples is 2.27. Forecasting for cash flow is not applied over 4 years, but mainly 2-3 years. The accuracy of forecasting was 18.8%, 34.4% and 8% according to the different definitions. No differences were found in the accuracy of forecasting between valuation methods, between the industries having more intangible assets and the industries having less, and between startups and general companies and between ages and listed ages.
Comparison of the Valuation of Technology Firms in KOSPI and KOSDAQ
조기헌,고창룡 아시아기술혁신학회 2015 Asian Journal of Innovation and Policy Vol.4 No.1
The purpose of this study is to compare the valuation of technology firms in the KOSPI and KOSDAQ. This study analyzed 224 market reports for KOSDAQ firms and 602 reports for KOSPI firms. We compare the two markets under 3 definitions on the accuracy of stock price forecasting. Findings are as follows: Although PER multiples is the most used method of valuation, KOSDAQ valuation more heavily relies on the method than KOSPI valuation. In stock market, the period of earnings forecasting is mostly 2-3 years. Multiples of KOSDAQ is generally higher than those of KOSPI. Even for technology firms, valuation in KOSPI mostly relies on earnings of the company, but that in KOSDAQ mostly relies on relative price. In stock price forecasting, generally overestimation prevails. Moreover, forecasting of KOSPI reports is more accurate than that of KOSDAQ reports. ROE and COE of KOSDAQ firms are generally higher than those of KOSPI firms.
Ho:YAG 레이저를 이용하여 제거한 하비갑개에 발생한 동정맥기형 1례
조기헌,이동우,천봉권,이환호 대한이비인후과학회 부산,울산,경남 지부회 2021 임상이비인후과 Vol.32 No.3
Vascular malformations are rare vascular diseases composed of improperly connected vasculature. Arteriovenous malformations (AVMs), havening direct communication between artery and vein without capillary beds, are rare among all vascular malformations. Most AVMs are found intracranially, extracranial AVMs mostly affect the head and neck area. We report an unusual case of a 52-year-old female who was presenting nasal obstruction and diagnosed with AVM originated from the inferior turbinate as a final pathology. Preoperative selective emboli- zation and complete excision of the tumor is the gold standard to treat AVM due to its rich vascular formation. As Holmium:yttrium-aluminium-garnet laser (Ho:YAG laser) is well-known for photocoagulation, hemostasis, and precise excision of tissue, we performed partial inferior turbinectomy with Ho:YAG laser without preoper- ative selective embolization. The patient was followed-up for four years and did not presented any other nasal symptoms. By this case, we propose that surgical excision with Ho:YAG laser without preoperative selective embolization is feasible for treatment of small AVM without invasion of adjacent tissue.
경비강 내시경 수술을 이용한 재발성 비인두암의 치험 1예
서윤수,조기헌,이형신 대한이비인후과학회 부산,울산,경남 지부회 2019 임상이비인후과 Vol.30 No.2
A 59-year-old male treated with radiotherapy presented with recurrent nasopharyngeal mass during the follow- up period of 21 months. Recurrence was confirmed by biopsy. The recurrence was relatively localized and no re- gional or distal metastasis was observed by imaging study. Transnasal endoscopic excision of tumor was per- formed with safety margin of 0.5 cm. The patient was discharged 1 day after surgery without any complication and there was no recurrence during the follow-up period of 2 years. In this case, we propose that surgical remov- al by transnasal endoscopic approach is feasible for treatment of early-stage recurrent nasopharyngeal cancer.
박윤창,조기헌 한국공작기계학회 2005 한국공작기계학회 춘계학술대회논문집 Vol.2005 No.-
In this paper we write to the result of measuring human body shape method - ibs-2000 - for human body shape measurement. The size measurement units and measuring speed is very inportant to efficiency of human body shape measurement units. By polygonal mirror system, the size measurement units and measuring time can be retrench.
박윤창,조기헌 한국생산제조학회 2005 한국생산제조시스템학회 학술발표대회 논문집 Vol.2005 No.5
In this paper we write to the result of measuring human body shape method - ibs-2000 for human body shape measurement. The size measurement units and measuring speed is very inportant to efficiency of human body shape measurement units. By polygonal mirror system, the size measurement units and measuring time can be retrench.