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DGS 회로를 이용한 IMT-2000용 전력증폭기의 설계 및 구현
차용성(Yong-Sung Cha),강병권(Byeong-Gwon Kang),김선형,박준석(Jun-Seok Park) 한국정보기술학회 2002 Proceedings of KIIT Conference Vol.2002 No.-
본 논문에서는 IMT-2000용 전력 증폭기를 설계 및 제작하였다. 전력증폭기의 주파수 대역은 IMT-2000용 순방향 주파수인 2110㎒~2170㎒에서 AB급으로 동작하도록 하였고, 고효율성과 우수한 선형성 소자인 LDMOSFET를 사용하였다. 설계 특성에 맞는 최적부하를 찾아 마이크로 스트립 회로로 입력 및 출력 정합 회로를 구현하였다. 임피던스 정합 방법으로는 소자를 실제 측정상태에서 입력단과 출력단에 튜너를 삽입하고 기본 주파수에서 최대 출력상태를 만족하는 임피던스를 튜너로 구현한 후, 튜너를 제거하고 튜너의 입력 임피던스를 Network Analyzer로 측정하여 최적 부하 임피던스를 추출하는 로드풀 방법을 사용하였다. 대전력 증폭기의 측정결과로는 2-톤 인가시 40.57㏈m의 출력결과를 얻을 수 있었고-30.61㏈c의 상호 혼변조 특성을 확인하였으며, 원신호의 하모닉(Harmonic) 주파수 성분과는 -19.56㏈c의 차이를 보였고, DGS 회로를 적용한 증폭기의 시뮬레이션 결과 -30㏈c 이상의 감쇠를 보임으로서 하모닉 성분을 억제시키는 결과를 확인하였다.
차용성 ( Yong Sung Cha ),이강현 ( Kang Hyun Lee ),김선휴 ( Sun Hyu Kim ),장용수 ( Yong Su Jang ),김현 ( Hyun Kim ),신태용 ( Tae Yong Shin ),황성오 ( Sung Oh Hwang ) 대한외상학회 2007 大韓外傷學會誌 Vol.20 No.1
Purpose: Few studies have been done for spinal injuries after skiing and snowboarding accidents. Assuming that the riding patterns of skiing and snowboarding were different, we analyzed the differences between the mechanisms, diagnoses and levels of spinal injuries caused by them. The purpose of this study was to gain a better understanding of spinal hazards associated with skiing and snowboarding in order to educate skiers and snowboarders. Methods: We conducted a prospective study of 96 patients who had sustained spinal injuries as a result of skiing and snowboarding accidents from January 2003 to March 2006. We used a questionnaire, radiological studies, history taking, and physical examinations. We analyzed the mechanism of injury, the level of spinal injury, the severity of spinal injury, and the Abbreviated Injury Scale scores (AIS score). We used the t-test and the chi-square test. Results: The skiing and the snowboarding injury group included in 96 patients. The skiing injury group included 30 patients (31.2%), and the snowboarding injury group included the remaining 66 patients (69.8%). The primary mechanism of injury in skiing was collisions and in snowboarding was slip downs (p=0.508). The primary level of spinal injury in skiing and snowboarding was at the L-spine level (p=0.547). The most common athlete ability of the injured person was at the intermediate level (p=0.954). The injured were most commonly at the beginner or the intermediate level (p=0.302). The primary diagnosis of spinal injury in skiing and snowboarding was back spain (p=0.686). The AIS scores did not differed between the two groups (p=0.986). Conclusion: The most common spinal injury after skiing and snowboarding accidents was back sprain. There was no difference in the severity of spinal injury between skiing and snowboarding accidents. (J Korean Soc Traumatol 2007;20:33-39)
김용원 ( Yong Won Kim ),김현 ( Hyun Kim ),차경철 ( Kyoung Chul Cha ),신형진 ( Hyung Jin Shin ),차용성 ( Yong Sung Cha ),이강현 ( Kang Hyun Lee ),황성오 ( Sung Oh Hwang ) 대한임상독성학회 2011 대한임상독성학회지 Vol.9 No.1
Purpose: Although glyphosate-surfactant herbicide intoxication is relatively mild toxic in humans, we encountered an atypical clinical presentation. We performed this study to understand the atypical clinical course and factors associated with severe intoxication after glyphosate ingestion. Methods: We conducted a retrospective study of 61 patients (male 43, mean age 54±18.8 years) who were presented with glyphosate ingestion between March 1997 and March 2011. The severe intoxication group was defined as patients with systolic blood pressure less than 90 mmHg, respiratory distress needing intubation, or altered mental state. Results: Of the 61 patients, 22 patients (36.1%) had a severe clinical course, 1 patient (1.6%) had died and 1 patient (1.6%) had moribund discharge. The most common symptoms were nausea with or without vomiting which occurred in 30 patients (49.2%). Twenty-seven patients had metabolic acidosis that was the second most common medical complication. Advanced age, pH, base excess, HCO3, Sat, creatinine, X-ray abnormalities and ECG abnormalities were significant factors. Hemoglobin, platelet, pO2, pCO2, BUN, sodium, potassium and AST levels were not different comparing the laboratory characteristics between the severe and mild intoxication groups. Conclusion: The results of this study showed that severe intoxication occurred in 22 patients (36.1%) after glyphosate intoxication. Advanced age, pH, base excess, HCO3, Sat, creatinine, X-ray abnormality and ECG abnormalities were significant predictive factors for severe intoxication in patients with glyphosate surfactant herbicide poisoning.
의식이 명료한 일산화탄소 중독환자를 대상으로 응급실에서 시행한 간이정신상태검사의 임상적 의의
육현 ( Hyun Youk ),차용성 ( Yong Sung Cha ),김현 ( Hyun Kim ),김성훈 ( Sung Hoon Kim ),김지현 ( Ji Hyun Kim ),김오현 ( Oh Hyun Kim ),김형일 ( Hyung Il Kim ),차경철 ( Kyoung Chul Cha ),이강현 ( Kang Hyun Lee ),황성오 ( Sung Oh Hw 대한임상독성학회 2016 대한임상독성학회지 Vol.14 No.2
Purpose: Because carbon monoxide (CO)-intoxicated patients with an alert mental status and only mild cognitive dysfunction may be inadequately assessed by traditional bedside neurologic examination in the emergency department (ED), they may not receive appropriate treatment. Methods: We retrospectively investigated the incidence and features of cognitive dysfunction using the Korean version of the Mini-Mental State Examination (MMSE-K) in ED patients with CO poisoning with alert mental status. We conducted a retrospective review of 43 consecutive mild CO poisoned patients with a Glasgow Coma Scale score of 15 based on documentation by the treating emergency physician in the ED between July 2014 and August 2015. Results: Cognitive dysfunction, defined as a score of less than 24 in the MMSE-K, was diagnosed in six patients (14%) in the ED. In the MMSE-K, orientation to time, memory recall, and concentration/calculation showed greater impairments. The mean age was significantly older in the cognitive dysfunction group than the non-cognitive dysfunction group (45.3 yrs vs. 66.5 yrs, p<0.001). Among the initial symptoms, experience of a transient change in mental status before ED arrival was significantly more common in the cognitive dysfunction group (32.4% vs. 100%, p=0.003). Conclusion: Patients with CO poisoning and an alert mental status may experience cognitive dysfunction as assessed using the MMSE-K during the early stages of evaluation in the ED. In the MMSE-K, orientation to time, memory recall, and concentration/calculation showed the greatest impairment.
박요섭 ( Joseph Park ),김용원 ( Yong Won Kim ),오세현 ( Se Hyun Oh ),차용성 ( Yong Sung Cha ),차경철 ( Kyoung Chul Cha ),김오현 ( Oh Hyun Kim ),이강현 ( Kang Hyun Lee ),황성오 ( Sung Oh Hwang ),김현 ( Hyun Kim ) 대한임상독성학회 2014 대한임상독성학회지 Vol.12 No.2
Purpose: Carbamate insecticides are potent cholinesterase inhibitors capable of causing severe cholinergic toxicity. Use of carbamate rather than organophosphate insecticides has been increasing. Compared with organophosphate poisoning, relatively few studies have investigated carbamate-associated acute pancreatitis. We investigated general characteristics and pancreatitis of carbamate poisoning and the predictors, among those readily assessed in the emergency department. Methods: We performed a retrospective review of consecutive patients, aged over 18 years, who were admitted between January 2008 and April 2012 to an emergency department (ED) of an academic tertiary care center for treatment of carbamate poisoning. Patients who exhibited poisoning by any other material, except alcohol, were excluded. After application of exclusion criteria, patients were divided according to carbamate-induced pancreatitis and non-pancreatitis groups. Results: A total of 41 patients were included in this study. Among these 41 patients, the prevalence of acute pancreatitis was 36.6% (15 patients). Initial blood chemistry tests showed a statistically higher glucose level in the pancreatitis group, compared with the non-pancreatitis group (222, IQR 189-284 vs. 137, IQR 122-175 mg/dL, P<0.05). Regarding clinical courses and outcomes, a significantly higher proportion of patients developed pneumonia [10 (66.7%) vs. 6 (23.1%), P<0.05] and had a longer hospital stay (7 days, IQR 6-12 vs. 5 days, IQR 2-11, P<0.05), but no difference in mortality, in the pancreatitis group vs. the non-pancreatitis group. In multivariate analysis, the initial glucose was showing significant association with the presentation of carbamate-induced acute pancreatitis (odds ratio 1.018, 95% confidence interval 1.001-1.035, P<0.05). Conclusion: Carbamate-induced acute pancreatitis is common, but not fatal. Initial serum glucose level is associated with acute pancreatitis.
만성 리튬 중독환자의 지연성 정정맥 혈액 투석여과 사례
김태수 ( Tae Su Kim ),차용성 ( Yong Sung Cha ),김김현 ( Hyun Kim ),김오현 ( Oh Hyun Kim ),차경철 ( Kyoung Chul Cha ),이강현 ( Kang Hyun Lee ),황성오 ( Sung Oh Hwang ) 대한임상독성학회 2013 대한임상독성학회지 Vol.11 No.1
A 66-year-old male with chronic alcoholism presented with tremor, gait disturbance, memory impairment, insomnia, decreased appetite, and confusion. The patient had been taking lithium daily for treatment of bipolar disorder. Brain CT showed no specific abnormality, and serum lithium and ammonia levels were 3.63 mEq/L (therapeutic range, 0.6~1.2 mEq/L) and 85μg/dL (reference range: 19~54μg/dL), respectively. Therefore, the initial differential diagnosis included chronic lithium intoxication, hepatic encephalopathy, Wernicke encephalopathy, or alcohol withdrawal syndrome. Even with the provision of adequate hydration, the patient’s neurologic status did not show improvement, so that lactulose enema, thiamine replacement, and continuous venovenous hemodiafiltration (CVVHDF) were started on the third admission day. By the fifth admission day he had made a rapid neurologic recovery, and was discharged on the 20th admission day. Therefore, CVVHDF might be a treatment for patients with chronic lithium intoxication, because, even if serum lithium concentration is normal, lithium concentration in the brain may be different from that of the serum.
정우진 ( Woo Jin Jung ),차용성 ( Yong Sung Cha ),이동건 ( Dong Keon Lee ),김김현 ( Hyun Kim ) 대한임상독성학회 2014 대한임상독성학회지 Vol.12 No.2
Pyrethroids have been widely using insecticides. Although generally regarded as less toxic to mammals including humans, we report one fatal case of pyrethroid poisoning with severe brain injury.
정우진 ( Woo Jin Jung ),김현 ( Hyun Kim ),차용성 ( Yong Sung Cha ),김오현 ( Oh Hyun Kim ),차경철 ( Kyoung Chul Cha ),이강현 ( Kang Hyun Lee ),황성오 ( Sung Oh Hwang ) 대한임상독성학회 2012 대한임상독성학회지 Vol.10 No.1
Purpose: Herbal preparations have long been used for medical purposes by traditional cultures, and their use is increasing in modern societies. However, many herbal agents produce specific cardiovascular toxicities in humans. We performed this study in order to investigate the clinical characteristics of the cardiac toxicities associated with herbal remedies. Methods: We conducted a retrospective study of 45 patients (mean age 57±10 years) who presented with cardiotoxicity between January 2007 and May 2011 due to ingestion of herbal remedy substances. Patients were identified as suffering cardiotoxicity if they presented with chest pain, EKG abnormality, and elevation of cardiac enzyme. Results: Of the 45 total cases, 17 included hemodynamic instability (37.8%), 7 with increasing cardiac enzyme (15.6%), 2 with cardiac arrest (4.4%) and one case of mortality (2.2%). The cardiotoxic herb group that demonstrated the worst clinical course was Ranunculaceae. Conclusions: In our study results, 57.6% of the herbal intoxication patients demonstrated the effects of cardiotoxicity. Thus, we recommend careful monitoring of herbal intoxication patients.
김태훈 ( Tae Hoon Kim ),김현 ( Hyun Kim ),김오현 ( Oh Hyun Kim ),차용성 ( Yong Sung Cha ),차경철 ( Kyoung Chul Cha ),이강현 ( Kang Hyun Lee ),황성오 ( Sung Oh Hwang ) 대한임상독성학회 2012 대한임상독성학회지 Vol.10 No.1
Recently, some patients have visited the emergency department for treatment of different symptoms of acute poisoning after intake of unidentified herbs, which can be mistaken for wild edible greens, because wild edible greens are good for health and contain vitamins, enzymes, minerals, fibers, and anticancer materials. Winter or early spring, is extremely high, with rapid onset of severe symptoms of poisoning. There have been no reports of poisoning by SymplocarpusRenifolius in Korea, however, we report on three severe cases involving patients who experienced cardiogenic shock with nausea, vomiting, abdominal pain, chest discomfort, dizziness, numbness, and general weakness.