Wesley's Tool-Box

On December 12, 2016, SK Telecom expanded its Smart Home suite by releasing a device set called Jikimi ("Protector") for basic home security. It consists of an SOS button that can notify either the police or someone you know, and a door sensor that can detect intrusion. They can be bought separately, and while the list price is KRW35,000 (US$30.70) for the button and KRW45,000 (US$39.50) for the sensor, it's currently being sold at a significant discount - KRW22,500 (US$19.70) and KRW24,000 (US$21), respectively. As far as networked sensors go, the discounted price is reasonable. I managed to buy a few of these shortly after they became available to gauge their usefulness.


Both devices come in an identically sized box roughly the size of a hockey puck. An instruction manual and two security stickers are included with each device. The stickers are meant to warn off would-be intruders. While I doubt they would be much of a deterrent, the large one refers to an actual NSOK security dispatch service for the SOS button which you can optionally enroll for an extra KRW40,000(US$35) per year. It's not available for door sensor users, but this sticker is included with that device as well.

Although the devices are meant to be installed on a wall or a door, they have to be taken off from time to time because the battery will become discharged after a few months and have to be taken care of. So you install the included hook first by peeling off its back and sticking it to a desired location. The device can then be mounted on or taken off the hook with little effort. An extra set of hook and adhesive pad is included should you need to change the installed location later on.


The Smart Home app paired with the devices will tell you how much battery charge is left in each of these devices, so when you realize that it's running low, you can take it off and plug it into a MicroUSB cable to recharge the internal Li-Ion battery. Officially, a two-hour charge will give about six months' use. In my case, the door sensor's at 39% and the main SOS button is at 53% after 75 days, so I would expect them to go for roughly 4 and 5 months total, respectively.


When installing the door sensor, the main unit and the magnet are aligned with the help with the center notch, and the two should preferably be within a centimeter apart. When the movement of the magnet is detected, a blue light briefly turns on. The main unit makes a sound with each detection before pairing, but it turns silent once the pairing is complete. The app has been reporting all the detection within about 3 seconds, so I found it to be reliable.


In the case of the SOS button, you simply stick it where it's easily accessible in case of emergency. I put one where the kids can find it quickly, and taught them to never press it just for fun. Actual cases where the button press was necessary is quite far and few between, but the presses were sent and received quickly and reliably similar to the door sensors. Accidentally brushing up the button isn't an issue, because the button needs to be pressed continuously for more than 0.5 seconds to activate. We had a few occasions of brushing up, but they didn't lead to an alarm.

These buttons serve the sole purpose of signaling an emergency, so even if you have more than one, they all appear under a single entry labeled "SOS버튼(SOS button)" in the Smart Home app. This is in contrast to the door sensors, which are each listed separately in order to let you know which particular door is open at the moment.

Like many of the offerings for SKT Smart Home, there's no monthly charge for using these. Coupled with the sensible discount price, they offer a good value in providing some peace of mind for your home. In a way, they are items that entice people to try the platform without investing too much into it.