경영학전공 대입전형 간 GPA와 이탈률 비교 연구

최덕현 한국교통대학교 2018 한국교통대학교 논문집 Vol.53 No.-

Nowadays, a variety of admission systems have been applied as an attempt to improve university admission system. In this study, for the purpose of scrutinizing the influence of admission systems on GPA and defection rate within business administration major context, statistical tests was conducted with 231 students data. For this study, the types of admission system were categorized into four types (regular admission, nonscheduled general admission, admission officer system, and special admission). The results of analysis of variance and cross-tabulation analysis showed that there is no significant relationship between admission types and GPA. The relationship between admission types and defection rate was not significant in the context of business administration major. Thus, it seems that the customized follow-up services for each admission types are not required for business administration major. In addition, it seems that there are not any urgent necessities for admission systems changes.

Association between Sleep Quality and Painless Diabetic Peripheral Neuropathy Assessed by Current Perception Threshold in Type 2 Diabetes Mellitus

최덕현,김보연,정찬희,김철희,목지오 대한당뇨병학회 2021 Diabetes and Metabolism Journal Vol.45 No.3

Background: It is known that the painful sensation of diabetic peripheral neuropathy (DPN) results in sleep problems in type 2 diabetes mellitus (T2DM). However, it is not known that the painless DPN also is associated with poor sleep quality in T2DM. The purpose of the current study was to investigate the association between painless DPN and poor sleep quality in T2DM. Methods: A total of 146 patients of T2DM who do not have any painful symptoms of DPN were recruited into the study. Among the patients, painless DPN was diagnosed by using the current perception threshold test. Sleep quality was assessed using the Pittsburgh Sleep Quality Index questionnaire. Results: The percentage of painless DPN was significantly higher in the poor sleep quality group than the good sleep quality group (70.0% vs. 35.5%, P<0.001). In the subscale results, stimulus values at 2,000 Hz, hypoesthesia and hyperesthesia were more common in the poor sleep quality group than in the good sleep quality group (45.7% vs. 25.0%, P=0.009; 34.3% vs. 18.4%, P=0.029; 40.0% vs. 19.7%, P=0.007, respectively). The association of painless DPN and poor sleep quality remained significant after adjustment for significant covariates (odds ratio, 3.825; 95% confidence interval, 1.674 to 8.742; P<0.001). Conclusion: The current study showed that painless DPN was associated with poor sleep quality. Future studies are required to clarify the pathophysiologic causal relationship between painless DPN and sleep quality.

The Role of Trust in Service Provider in Social Networking Service Context

최덕현 한국자료분석학회 2011 Journal of the Korean Data Analysis Society Vol.13 No.5

With an actual occurrence of hacking attacks onto major social networking service providers in Korea, there are growing concerns about users giving out too much personal information, the possible leaks of the personal information and improper use of it. For on-going service use, it is required for social networking service provider to institute and enforce fair rules, procedures, and outcomes in its services competently, reliably, and with integrity. Although expectation-confirmation has successfully explained general information technology usage continuance, trust in service provider could be also integrated as a critical variable for investigating social networking service context. For an empirical exploration, 268 samples were collected from the users of a social networking site. The results of data analysis confirm that the construct of trust in service provider is induced by confirmation and satisfaction. And, in turn, it contributes significantly to continuance intention. The results of this paper might be useful for future research on post-acceptance behavior in social networking service.

Measurement of the pore sizes for anodic aluminum oxide (AAO)

최덕현,P.S. Lee,황운봉,이건홍,H.C. Park 한국물리학회 2006 Current Applied Physics Vol.6 No.1l

A new method for the measurement of pore size of the porous-type anodic aluminum oxide (AAO) using atomic force microscopy(AFM) is proposed. The measurement of the pore size by AFM makes no damage to the specimen. AAO lm can be referred as a nano-honeycomb structure because the pore shape of AAO is like the honeycomb structure and its pore size is in the nanometer scale. Tomeasure the pore sizes from AFM images, it is assumed that the top surface of AAO is not etched much in the pore widening process.The pore sizes from AFM images showed good agreement with those from SEM images.

전격성 제1형 당뇨병에서 대장내시경 후 발생한 당뇨병케톤산증 1예

최덕현,김보연,정찬희,김철희,강성구,목지오 대한내과학회 2018 대한내과학회지 Vol.93 No.2

Fulminant type 1 diabetes is a distinct subtype of type 1 diabetes mellitus that is characterized by sudden, complete destruction of pancreatic beta cells at the disease onset. Since the disease was first described in 2000 in Japan, a number of case reports have also been published in Korea. However, this disease entity is still not well defined. A 48-year old man with no medical history was admitted with diabetic ketoacidosis. Fulminant type 1 diabetes was diagnosed and he was discharged with multiple insulin injections. His serum glucose level was well controlled in the outpatient clinic. A month later, diabetic ketoacidosis occurred again following a diagnostic colonoscopy. This case suggests that fulminant type 1 diabetes is an aggressive disease in which small stimuli can provoke ketoacidosis. Therefore, for tests that require fasting, close observation by medical staff and patient education about the disease is essential. 저자들은 혈당조절이 원활하였으며 다른 유발 요인이 없던 전격성 제1형 당뇨병 환자에서, 진단적 대장내시경 검사직후 당뇨병케톤산증이 발생한 증례를 경험하였기에 문헌고찰과 함께 보고하는 바이다.

Long-term investigation of erosion behaviors on metal surfaces by impingement of liquid droplet with high-speed

최덕현,김경훈,김형준 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.3

Understanding wall-thinning erosion of pipelines in nuclear or steam power plants is critically important for predicting and preventinghuman and material accidents. Wall thinning of pipelines in power plants occurs mainly by flow acceleration corrosion (FAC), cavitationerosion (C/E), and liquid droplet impingement erosion (LIE). Wall thinning by FAC and C/E has been well-investigated; however, LIE inplant industries has rarely been studied due to the experimental difficulty of setting up a long injection of highly pressurized air. We designeda long-term experimental system for LIE and investigated the behavior of LIE for three kinds of materials (A106B, SS400,A6061). The main control parameter was the air-water ratio (α), which was defined as the volumetric ratio of water to air (0.79, 1.00,1.72). To clearly understand LIE, the spraying velocity (v) of liquid droplets was controlled larger than 160 m/s and the experiments wereperformed for 15 days. The surface morphology and hardness of the materials were examined every five days. Since the spraying velocityof liquid droplets and their contact area (Ac) on specimens were changed according to the air-water ratio, we analyzed the behavior ofLIE for the materials using the impulse (I), which was defined as I = (α × v) / Ac. Finally, the prediction equations (the erosion rate) forthe LIE of the materials were determined for the air-water ratios.

환경공학전공 대입전형 간 GPA와 이탈률 비교 연구

최덕현 韓國交通大學校 2022 한국교통대학교 논문집 Vol.57 No.-

Nowadays, as an attempt to improve education policies, a variety of admission systems have been devised and applied to university admission system. To scrutinize the relationship between admission systems and GPA/defection rate within environmental engineering major context, this study conducted statistical tests with 296 students data. For this purpose, the types of admission system were categorized into four types in this study (regular admission, nonscheduled general admission, admission officer system, and special admission). The results of analysis of variance showed that there are no significant difference in GPA among the four admission types. With regard to GAP trend, the recent student group in nonscheduled general admission type and admission officer system type showed positive GPA trend. On the contrary, the recent student group in the case of regular admission type and special admission type showed negative GPA trend. The results of cross-tabulation analysis showed no significant relationship between admission types and defection rate. But, it seems notable that the type of special admission showed the higher defection rate compared to other admission types. Although it seems that substantial change in the admission system is not necessary in environmental engineering major, it is worth considering the increase of nonscheduled general admission type and admission officer system type and the decrease of special admission type.

A Dichotomous Approach for Trust in Social Networking Service

최덕현 한국자료분석학회 2012 Journal of the Korean Data Analysis Society Vol.14 No.5

With the prevalence of social networking service (SNS), there are growing concerns over users giving out too much personal information and the possible leaks and improper use of it. For on-going use of SNS, trust in service provider has been proposed as a serious issue in this field. However, considering the main purpose of SNS use is to build and develop interpersonal relationship, the benevolence/integrity of other users can be more critical determinant for service use continuance. To reflect the property of SNS context, this study proposed a dichotomous approach for trust constructs, in which trust in service provider and trust in other users were examined simultaneously. For an empirical exploration, 268 samples were collected from the users of a social networking site. The results of a multiple regression analysis confirmed that continuance intention in SNS context is influenced by trust in other users rather than by trust in service provider. The results of this exploratory study might be useful for future research on trust construct in SNS context.

기계공학전공 대입전형 간 GPA와 이탈률 비교 연구

최덕현 한국교통대학교 2020 한국교통대학교 논문집 Vol.55 No.-

As an attempt to improve university admission system, a variety of admission systems have been devised and applied in nowadays education policies. With the purpose of scrutinizing the relationship between admission systems and GPA/defection rate within mechanical engineering major context, this study conducted statistical tests with 451 students data. The types of admission system were categorized into four types (regular admission, nonscheduled general admission, admission officer system, and special admission) in this study. The results of analysis of variance showed that regular admission has the higher GPA than other types. The results of cross-tabulation analysis showed that there is no significant relationship between admission types and defection rate, but the type of special admission showed the higher defection rate compared to other admission types in the mechanical engineering major. Thus, it seems that the customized follow-up services for special admission type is required for mechanical engineering major. In addition, it seems possible to adjust the portion of regular admission type and special admission type for better student's academic ability and lower defection rate.

Nonalcoholic Fatty Liver Disease and Abdominal Fat Accumulation According to Vitamin D Status in Patients with Type 2 Diabetes

최덕현,정찬희,목지오,김철희,강성구,김보연 대한비만학회 2018 The Korean journal of obesity Vol.27 No.1

Background: Vitamin D deficiency is known to increase the incidence of metabolic syndrome. Nonalcoholic fatty liver disease is a common metabolic disease in patients with type 2 diabetes. This study evaluated nonalcoholic fatty liver disease and abdominal fat accumulation according to 25-hydroxyvitamin D status in patients with type 2 diabetes. Methods: The study comprised 302 patients with type 2 diabetes. Patients were divided into three groups based upon their 25-hydroxyvitamin D status: vitamin D deficient group (<10 ng/mL), vitamin D insufficient group (≥10 to <20 ng/mL) and vitamin D sufficient group (≥20 ng/mL). Patient clinical and laboratory markers were evaluated retrospectively. Results: Visceral fat thickness was significantly higher in the vitamin D deficient group. There were no differences in glycemic control, body mass index, and subcutaneous fat thickness correlated with 25-hydroxyvitamin D status. The prevalence of nonalcoholic fatty liver disease was significantly higher in the vitamin D deficient group compared to the vitamin D sufficient and vitamin D insufficient groups. In multivariate logistic analysis, after adjustment for age, sex, body mass index, glycated hemoglobin and homeostasis model assessment of insulin resistance, patients with type 2 diabetes in the vitamin D sufficient group showed significantly lower odds ratio for nonalcoholic fatty liver disease than those within the vitamin D deficient group. Conclusion: In type 2 diabetes, the vitamin D deficient group showed thicker visceral fat thickness and higher nonalcoholic fatty liver disease prevalence.