Yun Gon Lee

Recent Changes in Downward Longwave Radiation at King Sejong Station, Antarctica

Abstract Effects of cloud, air temperature, and specific humidity on downward longwave irradiance and their long-term variabilities are examined by analyzing the measurements made at the King Sejong Station in the Antarctic Peninsula during the period of 1996–2006. It has been shown that the downward longwave irradiance (DLR) is significantly correlated with three variables: air temperature, specific humidity, and cloudiness. Based on the relationship of the three variables with DLR, a multiple linear regression model has been developed in order to evaluate the relative contribution of each of the variables to the variation of DLR. The three variables together explained 75% of all the variance in daily mean DLR. The respective contribution from specific humidity and cloudiness to the variation of DLR was 46% and 23%; thus most of the DLR variability can be explained by the variations in the two variables. The annual mean of longwave cloud forcing shows 52 W m−2 with no remarkable seasonal cycle. It is als...

Effect of antihistamine as an adjuvant treatment of isotretinoin in acne: a randomized, controlled comparative study

Isotretinoin has been frequently used for acne therapy. However, it has limitation in acceptance because of its adverse effects. Although antihistamine recently revealed to decrease the lipogenesis, evidence is lacking regarding the clinical relevance of antihistamine in the treatment of acne.

High‐dose prednisolone and psoralen ultraviolet A combination therapy in 36 patients with vitiligo

It is well known that systemic corticosteroids arrest the progress of vitiligo and lead to repigmentation, but they may produce unacceptable side‐effects. The use of high‐dose prednisolone therapy to minimize the side‐effects of systemic steroids has been reported, but there have been no reports on the effectiveness of such treatment combined with phototherapy. We evaluated the efficacy and safety of combination therapy with intravenous prednisolone and psoralen ultraviolet A (PUVA). In 36 patients with vitiligo, intravenous methylprednisolone for 3 days was followed by PUVA twice weekly. After 6 months, vitiligo lesions on the face were reduced in size by 57.5%, on the upper extremities by 34.5%, on the trunk by 30.4% and on the lower extremities by 26.3%. Overall, improvement was seen in 13 patients (36.1%), with > 50% repigmentation. Side‐effects were mild and transient. We conclude that combination treatment of high‐dose prednisolone therapy and PUVA may represent a highly effective therapeutic option for generalized vitiligo.

Cutaneous lymphangiectasia associated with photoageing and topical corticosteroid application

We report the case of a 69‐year‐old man with a history of multiple erythematous bullae on both forearms, which had been present for about 1 month. The lesions appeared after several years of topical corticosteroid application and photoageing. A biopsy revealed lymphangiectasia with solar elastosis and increase in the ratio of elastic to collagen fibres in the dermis. We suggest that this patient’s lymphangiectasia resulted from abnormal structure and function of the dermis due to photoageing and steroid‐related atrophy.

Spectral Dependence on the Correction Factor of Erythemal UV for Cloud, Aerosol, Total Ozone, and Surface Properties: A Modeling Study

Radiative transfer model simulations were used to investigate the erythemal ultraviolet (EUV) correction factors by separating the UV-A and UV-B spectral ranges. The correction factor was defined as the ratio of EUV caused by changing the amounts and characteristics of the extinction and scattering materials. The EUV correction factors (CFEUV) for UV-A [CFEUV(A)] and UV-B [CFEUV(B)] were affected by changes in the total ozone, optical depths of aerosol and cloud, and the solar zenith angle. The differences between CFEUV(A) and CFEUV(B) were also estimated as a function of solar zenith angle, the optical depths of aerosol and cloud, and total ozone. The differences between CFEUV(A) and CFEUV(B) ranged from −5.0% to 25.0% for aerosols, and from −9.5% to 2.0% for clouds in all simulations for different solar zenith angles and optical depths of aerosol and cloud. The rate of decline of CFEUV per unit optical depth between UV-A and UV-B differed by up to 20% for the same aerosol and cloud conditions. For total ozone, the variation in CFEUV(A) was negligible compared with that in CFEUV(B) because of the effective spectral range of the ozone absorption band. In addition, the sensitivity of the CFEUVs due to changes in surface conditions (i.e., surface albedo and surface altitude) was also estimated by using the model in this study. For changes in surface albedo, the sensitivity of the CFEUVs was 2.9%–4.1% per 0.1 albedo change, depending on the amount of aerosols or clouds. For changes in surface altitude, the sensitivity of CFEUV(B) was twice that of CFEUV(A), because the Rayleigh optical depth increased significantly at shorter wavelengths.

Proton pump inhibitors as a possible cause of vitiligo: an in vivo and in vitro study.

Vitiligo is an acquired depigmentation disorder of melanocytes. Recently, some clinical reports have suggested that proton pump inhibitors (PPIs) may worsen vitiligo, but their effects on melanocytes have yet to be elucidated.

Estimation of Surface NO2 Volume Mixing Ratio in Four Metropolitan Cities in Korea Using Multiple Regression Models with OMI and AIRS Data

Surface NO2 volume mixing ratio (VMR) at a specific time (13:45 Local time) (NO2 VMRST) and monthly mean surface NO2 VMR (NO2 VMRM) are estimated for the first time using three regression models with Ozone Monitoring Instrument (OMI) data in four metropolitan cities in South Korea: Seoul, Gyeonggi, Daejeon, and Gwangju. Relationships between the surface NO2 VMR obtained from in situ measurements (NO2 VMRIn-situ) and tropospheric NO2 vertical column density obtained from OMI from 2007 to 2013 were developed using regression models that also include boundary layer height (BLH) from Atmospheric Infrared Sounder (AIRS) and surface pressure, temperature, dew point, and wind speed and direction. The performance of the regression models is evaluated via comparison with the NO2 VMRIn-situ for two validation years (2006 and 2014). Of the three regression models, a multiple regression model shows the best performance in estimating NO2 VMRST and NO2 VMRM. In the validation period, the average correlation coefficient (R), slope, mean bias (MB), mean absolute error (MAE), root mean square error (RMSE), and percent difference between NO2 VMRIn-situ and NO2 VMRST estimated by the multiple regression model are 0.66, 0.41, −1.36 ppbv, 6.89 ppbv, 8.98 ppbv, and 31.50%, respectively, while the average corresponding values for the other two models are 0.75, 0.41, −1.40 ppbv, 3.59 ppbv, 4.72 ppbv, and 16.59%, respectively. All three models have similar performance for NO2 VMRM, with average R, slope, MB, MAE, RMSE, and percent difference between NO2 VMRIn-situ and NO2 VMRM of 0.74, 0.49, −1.90 ppbv, 3.93 ppbv, 5.05 ppbv, and 18.76%, respectively.

The dependence of the surface solar irradiance on cloud and aerosol

To quantify radiative forcing of aerosol and to investigate the dependence of the horizontal UV, visible and NIR on total optical depth (TOD) and cloudiness, narrowband surface solar irradiances were measured and analyzed for direct and diffuse component. A MFRSR (Multifilter Rotating Shadowband Ratiometer) was used to measure the global, direct and diffuse solar irradiances atone broadband of 391–955 nm and 6 narrowband channels of 412.8, 495.2, 611.9, 672.2, 869, 936.6 nm for a year from Jan. to Dec. in 2006 at Yonsei University in Seoul and a UV‐MFRSR was used to measure irradiance at 7 narrowband channels of 299.1, 304.5, 310.7, 317.1, 323.8, 331.3, 367.4 nm in UV range during 7 months at the same location with the MFRSR.

A case of unilateral scrotal calcinosis

Scrotal calcinosis usually occurs during adolescence, and appears as asymptomatic hard nodules on the scrotum, which can be single or multiple. The nodules usually occur bilaterally, and usually increase in number over time. Unilateral scrotal calcinosis has not been reported previously in the dermatological literature, to our knowledge. We report a peculiar case of scrotal calcinosis, in which 20 nodules were limited to the left scrotum. They ranged in size from 2 to 10 mm. Over 2 months, they decreased slightly in size and number, and no new nodules developed. In April 2006, an 18-year-old man was admitted to our department with multiple subcutaneous nodules on the left scrotum that had occurred 1 month earlier. He reported that the number and size of the nodules had increased and were causing discomfort. On physical examination, 20 nodules ranging in size from 2 to 10 mm were seen (Fig. 1a). Histological examination of a skin biopsy specimen found amorphous basophilic calcium nodules in the dermis with no epidermal change (Fig. 1b). No epithelial lining or inflammatory cells were seen. The patient was in good health and claimed to have no underlying disease. He refused to undergo blood, urine or radiological tests. He was followed up carefully for 2 months, during which time the subcutaneous nodules decreased slightly in size and number (Fig. 1c). Scrotal calcinosis was first reported by Lewinski in 1883. It usually occurs during adolescence, appearing as a single nodule or multiple asymptomatic hard nodules, which can reach 30 mm in size, on the scrotum. Scrotal calcinosis is typically bilateral, and the number of nodules increases over time, with reported cases involving up to 51 nodules. Histopathological observations of scrotal calcinosis include amorphous basophilic calcium nodules on haematoxylin and eosin staining. With von Kossa stain, the nodules stain black. Some nodules have an epithelial lining. In addition, multinucleated megakaryocytes and inflammatory cells may be seen around the calcium deposits. Destruction of the nodules may result in the efflux of a chalk-like substance. The aetiopathogenesis of the disease remains controversial. Although no reports in the English literature have (a)

Multiple yellow–brown papules on the neck and anterior trunk of a patient with diabetes mellitus

A 20-year-old Korean woman presented with a 1-year history of an eruption that began as numerous papules on the neck and spread to cover a large area on the anterior trunk in successive crops. The neck eruption had recently become mildly pruritic. She had been hospitalized with diabetic ketoacidosis as a complication of uncontrolled type I diabetes mellitus. The eruption consisted of numerous yellow-brown, flat-topped papules, 1–5 mm in diameter, on the neck, anterior chest, and abdomen (Fig. 1). The lesions had coalesced in places to form plaques 5–15 mm in diameter. The lesions were bilateral and symmetrical, and had both a follicular and nonfollicular distribution. The patient was diagnosed 3 years ago with type I diabetes mellitus but had not begun treatment. Histopathological findings