Sung In Jang
Yonsei University · Medicine
About the Lab
Professor Sung In Jang's research lab focuses on the epidemiological and clinical investigation of lifestyle-related health risks, particularly examining the impacts of tobacco and nicotine use—such as conventional smoking, e-cigarette vaping, and dual use—on metabolic, cardiovascular, and liver diseases in the South Korean population. The lab emphasizes population-based studies using large-scale national health surveys to explore gender-specific, age-related, and behavioral patterns in disease associations. Key research directions include the links between smoking behaviors and conditions such as metabolic syndrome, nonalcoholic fatty liver disease, periodontal disease, and glycated hemoglobin levels, as well as the interplay between sedentary behavior, sleep quality, and health outcomes. The lab integrates statistical modeling and population health analytics to inform public health policy and preventive strategies.
Research Overview
Research Output Trend
Figures are computed from collected data and may differ slightly.
Selected Papers
15BACKGROUND: The aim of this study was to examine the association of conventional cigarette smoking and electronic cigarette vaping with periodontal disease in South Korean adults. METHODS: For this study, data from 13,551 participants, a subset derived from the Korean National Health and Nutrition Examination Survey conducted between 2013 and 2015, were examined. Participants were divided into four categories: electronic cigarettes vapers, conventional cigarettes smokers, ex-users, and non-users
BACKGROUND: Sleep problems increase the risk of premature illness and death. We evaluated the association between sedentary time and sleep quality among South Korean adults. METHODS: The data of adults (aged ≥ 19 years) from the 2018 Korea Community Health Survey were analyzed. Sedentary time, which included hours spent sitting or lying down daily, was categorized into four standardized groups. Poor sleep quality was defined using the global cutoff point (> 5 points) of the Pittsburg Sleep Quali
Background: Smoking is well known to be associated with a higher prevalence and incidence of liver diseases such as advanced fibrosis. However, the impact of smoking on developing nonalcoholic fatty liver disease remains controversial, and clinical data on this is limited. Therefore, this study aimed to investigate the association between smoking history and nonalcoholic fatty liver disease (NAFLD). Methods: Data from the Korea National Health and Nutrition Examination Survey 2019-2020 were used
Few studies have researched the gender-specific effects of electronic nicotine delivery systems on the metabolic syndrome (MetS) and/or its risk factors (central obesity, raised triglycerides, decreased HDL cholesterol, raised blood pressure, raised fasting plasma glucose). Thus, this study investigated the association between smoking behavior (cigarette type, smoking history) and MetS in a nationally representative sample of Korean men and women. Our study employed data for 5,462 cases of MetS
BACKGROUND: Cigarette smoking is a major health risk, particularly in male South Koreans. Smoking cessation can benefit health; however, the process of quitting smoking is difficult to some smokers and shows its relationship to their stress level. The hypothesis of this study is that who has failed attempts to stop smoking induce more stress than habitual smoking. METHODS: To test this, the analysis on the association between smoking cessation attempts and stress levels in smokers was performed.
This study investigated the association of smoking behaviors, including dual smoking (smoking both cigarettes and e-cigarettes), cigarettes smoking, and previous smoking, with glycated hemoglobin (HbA1c) levels. National Health and Nutrition Examination Survey (KNHANES) data from 2014–2016 was used. Associations between smoking behavior patterns and HbA1c levels were analyzed via multiple regression. Among 8809 participants, individuals who were dual smokers and cigarettes smokers had significan
Introduction: This study aims to investigate the association between gender discrimination in the workplace and pregnancy planning/childbirth experiences among working women in South Korea. Methods: We analyzed data from the Korean Longitudinal Survey of Women and Families (KLoWF) for the years 2007 to 2016. The study population consisted of 7996 working women, between the ages of 19 and 45. Gender discrimination was measured through the 6-item Workplace Gender Discrimination Scale, evaluating d
Within competitive sociocultural environments, most Korean workers are likely to shorten their sleep duration during the weekday. Short sleep duration is associated with dyslipidemia; however, studies on the correlation between various sleep patterns and dyslipidemia are still lacking. In hence this study aimed to investigate the association between weekend catch-up sleep (CUS) and dyslipidemia among South Korean workers. Our study used data from the 8th Korea National Health and Nutrition Exami
BACKGROUND: South Korea is an aged society that continues to age rapidly. Therefore, the purpose of this study was to investigate the association between changes in lifestyle and cognitive functions in the South Korean elderly using a nationally representative survey. METHODS: We analyzed data from the Korean Longitudinal Study of Aging (KLoSA) 2006-2016, a biannual panel survey. Multiple linear regression analysis was performed with repeated measurements data to examine the association between
BACKGROUND: Depression is a leading cause of disability, and it has been reported that more than 264 million people worldwide have depression. The causes of depression may be numerous, and physical health has also been linked to depression. Therefore, the aim of this study was to determine the effect of health behaviours on depression. METHODS: This study used the data of 224,868 participants from the Community Health Survey, conducted in 2017. We defined health behaviours by combining three var
Insulin resistance can be affected directly or indirectly by smoking. This cross-sectional study aimed at examining the association between smoking patterns and insulin resistance using objective biomarkers. Data from 4043 participants sourced from the Korea National Health and Nutrition Examination Survey, conducted from 2016 to 2018, were examined. Short-term smoking patterns were used to classify participants according to urine levels of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and cotin
Background: Atherosclerotic cardiovascular disease (ASCVD) is a preventable type of disease, thus, specifying factors that increase the occurrence of this type of disease is needed. Heavy metals such as cadmium (Cd), lead (Pb), and mercury (Hg) have been suggested as possible factors influencing the development of cardiovascular disease. We aimed to link blood heavy metal levels (Cd, Pb, Hg) with 10-year ASCVD risk scores. Methods: A population of 993 men and 1431 women who participated in the K
Research Areas
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